U.S. patent application number 14/720374 was filed with the patent office on 2021-03-25 for composite material.
The applicant listed for this patent is Greenhill AntiBallistics Corporation. Invention is credited to Yuval Avniel, Joseph J. Belbruno, Zachary R. Greenhill.
Application Number | 20210086475 14/720374 |
Document ID | / |
Family ID | 1000005444566 |
Filed Date | 2021-03-25 |
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United States Patent
Application |
20210086475 |
Kind Code |
A9 |
Greenhill; Zachary R. ; et
al. |
March 25, 2021 |
COMPOSITE MATERIAL
Abstract
Disclosed herein are engineered composite materials suitable for
applications that can benefit from a composite material capable of
interacting with or responding to, in a controlled or
pre-determined manner, changes in its surrounding environment. The
composite material is generally includes a gradient layer structure
of a sequence of at, e.g., three or more gradient-contributing
layers of microscale particles, wherein a mean particle size of
particles of neighboring gradient-contributing layers in the cross
section of the gradient layer structure varies from layer to layer,
thereby forming a particle size gradient, and in contact with the
gradient layer structure, a densely packed particle structure
including densely packed microscale particles, wherein a mean
particle size of the densely packed microscale particles does not
form a particle size gradient in the cross section of the densely
packed particle structure.
Inventors: |
Greenhill; Zachary R.; (Rye,
NY) ; Belbruno; Joseph J.; (Hanover, NH) ;
Avniel; Yuval; (Missoula, MT) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Greenhill AntiBallistics Corporation |
New York |
NY |
US |
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Prior
Publication: |
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Document Identifier |
Publication Date |
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US 20160159033 A1 |
June 9, 2016 |
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Family ID: |
1000005444566 |
Appl. No.: |
14/720374 |
Filed: |
May 22, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12672865 |
Feb 9, 2010 |
9060560 |
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PCT/US2009/053462 |
Aug 11, 2009 |
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14720374 |
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PCT/US2008/072808 |
Aug 11, 2008 |
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12672865 |
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PCT/US2009/053465 |
Aug 11, 2009 |
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12672865 |
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PCT/US2008/072808 |
Aug 11, 2008 |
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PCT/US2009/053465 |
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61153539 |
Feb 18, 2009 |
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61153539 |
Feb 18, 2009 |
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61031913 |
Feb 27, 2008 |
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60955335 |
Aug 10, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 5/30 20130101; B32B
5/16 20130101; B32B 2307/73 20130101; B32B 2457/00 20130101; B32B
27/302 20130101; B32B 2307/412 20130101 |
International
Class: |
B32B 5/30 20060101
B32B005/30; B32B 5/16 20060101 B32B005/16; B32B 27/30 20060101
B32B027/30 |
Claims
1-104. (canceled)
105. A composition comprising: a plurality of repeating units,
wherein each of the plurality of repeating units comprises: a first
layer of first particles having a first mean diameter; and a second
layer of second particles having a second mean diameter, wherein no
intermediary material essentially affecting the mobility of the
first particles or the second particles is between the first
particles within the first layer or between the second particles
within the second layer, wherein the first mean diameter and the
second mean diameter are less than approximately 500 nm.
106. The composition of claim 105, wherein the first particles or
the second particles are polystyrene.
107. The composition of claim 105, wherein the first particles or
the second particles are silica.
108. The composition of claim 107, wherein the first particles or
the second particles are polarized.
109. The composition of claim 105, wherein the first particles or
the second particles contain metal.
110. The composition of claim 109, wherein the first particles or
the second particles are copper.
111. The composition of claim 105, wherein a composition of the
first particles and a composition of the second particles are the
different.
112. The composition of claim 105, wherein at least a portion of
the first particles in the first layer contact at least a portion
of the second particles in the second layer.
113. The composition of claim 105, wherein at least a portion of
the first particles or the second particles of a repeating unit are
in contact with at least a portion of adjacent first particles or
adjacent second particles of an adjacent repeating unit.
114. The composition of claim 105, wherein the first layer and the
second layer comprise separate and distinct particles without
additional material in the first layer or in the second layer.
115. The composition of claim 105, further comprising a binding
layer between a repeating unit and an adjacent repeating unit.
116. The composition of claim 105, wherein at least one of the
plurality of repeating units is in contact with a substrate.
117. The composition of claim 116, wherein the substrate is at
least a portion of an electronic device.
118. The composition of claim 116, wherein the substrate is
glass.
119. The composition of claim 105, wherein the first mean diameter
and the second mean diameter are less than approximately 250
nm.
120. The composition of claim 105, wherein the first mean diameter
differs from the second mean diameter by between 5% and 50%.
121. The composition of claim 105, wherein at least one of the
plurality of repeating units comprises a third layer of third
particles of a third mean diameter.
122. The composition of claim 105, wherein the first particles or
the second particles comprise a binding coating.
123. The composition of claim 105, wherein the binding coating is
hydrophobic.
124. The composition of claim 105, wherein the composition is
transparent.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation-in-part of, and claims
priority under 35 U.S.C. .sctn.120 to PCT/US2008/072808, filed on
Aug. 11, 2008, entitled "COMPOSITE MATERIAL", and designating the
U.S., the contents of which is hereby incorporated by reference in
its entirety.
[0002] This application claims the benefit of priority under 35
U.S.C. .sctn.119(e) from U.S. Provisional Patent Application Ser.
No. 61/153,539, filed Feb. 18, 2009 and entitled "COMPOSITE
MATERIAL," the contents of which are hereby incorporated by
reference in its entirety.
TECHNICAL FIELD
[0003] The present invention relates to a composite material and,
in particular, to a composite material comprising one or more
layers of particles.
BACKGROUND
[0004] Material designs for handling the impact of an external
stimulus, such as a blast or projectiles, include, for example,
woven fabrics, ceramic materials, and composite systems.
Kevlar.RTM., Zylon.RTM., Armos.RTM., Spectra.RTM. are commercially
available fabrics made from high-strength fibers. Another material
is ballistic steel, which is comprised of hardened high tensile
steel, woven into fiber form. Further, boron carbide can be used as
a material, for example, in the production of body armor.
[0005] Ceramic materials, in particular ceramic metal composites
have found utility in light weight body armor; for examples, the
Blast-Tamer wall system from General Plastics Manufacturing Co.
(Tacoma, Wash.). The system consists of engineered polyurethane
foam panels tied together with adhesive joints and aramid
fiber.cord, with the space between the panels filled with sand.
SUMMARY
[0006] The invention is based in part on the fact that a composite
material with a structure that includes microscale particles that
can interact with each other can absorb, distort, and/or redirect a
compression wave, such as, e.g., a shock wave accompanying an
explosion. The invention is further based in part on the fact that
a composite material with a specific gradient layer structure can
absorb, distort, and/or redirect a compression wave, such as, e.g.,
a shock wave accompanying an explosion. The invention is also based
in part on the fact that a composite material with core-shell
particles can absorb, distort, and/or redirect a compression wave,
such as, e.g., a shock wave accompanying an explosion. In general,
composite materials (or composites) are engineered materials made
from two or more constituent materials (e.g., particles, core-shell
particles) with significantly different physical and/or chemical
properties that retain their separate and distinct physical and/or
chemical identities within the finished structure.
[0007] The invention is further based in part on the fact that a
composite material with a gradient layer structure comprising
particles with varying size arranged to form a gradient of the
particle size may provide increased hardness (relative, e.g., to a
material not in nanoparticle format) and shock absorbing features
when smaller particles form the surface of the composite material
or at least an interacting side of the composite material.
[0008] The invention is further based in part on the fact that a
composite material may provide upon activation specific reactions
and/or materials to its environment. For example, the composite
material and/or at least one of the materials constituting the
composite material can be further designed to mitigate and/or
remediate primary and/or secondary effects resulting from the
compression wave. Thus, some embodiments of the present invention
can provide novel composite materials that through intelligent
design of the composition of the materials and a structure within
the composite material can not only reduce (mitigate and/or
remediate) the impact of a shock wave (primary blast effect) with
greater efficiency and efficacy but that can also mitigate and/or
remediate one or more secondary blast effects. Moreover, the
composite material and/or at least one of the materials
constituting the composite material can be, for example, further
designed to be activated through a chemical signature in its
environment or through a physical condition (e.g., of a
compression) wave to change a physical and/or chemical property
such as color.
[0009] The invention is further based in part on the fact that a
composite material may use a compression wave to work against
itself to mitigate and/or remediate the primary and secondary
effects of the compression wave. Similarly, when an incident shock
wave is reflected from the composite material, the reflected shock
wave can be distorted. When the incident and reflected shock wave
form a combined shock wave, primary and secondary effects of the
combined shock wave can be mitigated and/or remediated due to the
distortion of the reflected shock wave.
[0010] In a first aspect, the invention features multilayer
composite materials that include a gradient layer structure of a
sequence of at least three gradient-contributing layers of
microscale particles, wherein a mean particle size of particles of
neighboring gradient-contributing layers in the cross section of
the gradient layer structure varies from layer to layer, thereby
forming a particle size gradient, and in contact with the gradient
layer structure, a densely packed particle structure including
densely packed microscale particles, wherein a mean particle size
of the densely packed microscale particles does not form a particle
size gradient in the cross section of the densely packed particle
structure. In another aspect, the invention features methods that
include attenuating a compression wave using a composite
material.
[0011] In another aspect, the invention features liners that
include a multilayer composite material.
[0012] In another aspect, the invention features receptacle that
include a multilayer composite material.
[0013] In another aspect, the invention features systems that
include a pipe; and a multilayer composite material.
[0014] In another aspect, the invention features helmet liner pads
that include a multilayer composite material.
[0015] In another aspect, the invention features helmets that
include a helmet structure and a multilayer composite material.
[0016] In another aspect, the invention features textiles that
include a multilayer composite material.
[0017] In another aspect, the invention features transportation
devices that include a body and a multilayer composite
material.
[0018] In another aspect, the invention features composite
materials that include a multilayer composite material, wherein the
composite material includes a color changing sensor material.
[0019] In another aspect, the invention features safety structure
that include a pair of structural elements and a multilayer
composite material.
[0020] In another aspect, the invention features multilayer
composite materials that include a first substrate and a layer
structure of a sequence of layers of microscale particles in
contact with the substrate at a first face of the layer structure,
wherein at least one layer of microscale particles includes
core-shell particles, the layer structure includes a region of
neighboring layers that form a gradient layer structure such that a
mean particle size of particles of the neighboring layers varies
along the cross section of the gradient layer structure within a
range of particle sizes, and the gradient layer structure forms a
second face of the layer structure opposite to the first face of
the layer structure with particles having a size at the lower end
of the range of particle sizes.
[0021] In another aspect, the invention features multilayer
composite materials that include a gradient layer structure of a
sequence of layers of microscale particles, wherein a mean particle
size of particles of neighboring layers in the cross section of the
gradient layer structure varies from layer to layer, thereby
forming a particle size gradient and at least one of the layers of
the gradient layer structure is configured to have a thickness
larger than a mean particle size of the particles of the respective
layer
[0022] Embodiments of the aspects can include one or more of the
following features.
[0023] In the multilayer composite material, a thickness of the
gradient layer structure and a thickness of the densely packed
particle structure can have a ratio of thickness in the range from
0.1 to 10.
[0024] The particles can include at least one particle selected
from the group consisting of solid particles and
core-shell-particles.
[0025] The multilayer composite materials can further comprise at
least one additional gradient layer structure and/or densely packed
particle structure and wherein the gradient layer structure, the
densely packed particle structure and the at least one additional
gradient layer structures and/or densely packed particle structure
are arranged as a sequence, where neighboring structures contact
each other at a common interface.
[0026] In some embodiments, the gradient layer structure is a first
gradient layer structure having a first particle size gradient in a
first direction and the composite material further comprises a
second gradient layer structure having a second particle size
gradient in the first, opposite to the first, or in a third
direction.
[0027] In some embodiments, the gradient layer structure can
include at least one layer with a particle size smaller than 1 mm,
0.1 mm, 0.04 mm, 1000 nm, 500 nm, 100 nm, or 10 nm.
[0028] In some embodiments, the gradient layer structure can
include at least one layer with a mean deviation below about 10%
for a median particle size distribution.
[0029] In some embodiments, densely packed microscale particles of
the densely packed particle structure can be at least partly
arranged in a layer structure.
[0030] In some embodiments, the layer structure of the densely
packed particle structure can include at least one layer with a
particle size smaller than 1 mm, 0.1 mm, 0.04 mm, 1000 nm, 500 nm,
100 nm, or 10 nm. The layer structure can include at least one
layer with a mean deviation below about 10% for a median particle
size distribution.
[0031] The method can include forming a sequence of particle layers
such that a gradient of the particle size over the sequence is
defined as a change in size of particles populating different
individual layers.
[0032] The methods can further use composite materials that include
at least one a core-shell particle, which contributes to the
attenuation of the compression wave. In some embodiments, energy
absorbed with the at least one core-shell particle is used to
release a core material from the core-shell particle.
[0033] The composite material can be used in various configurations
including a coating, e.g., sprayed to an underlying substrate, a
film (attachable to surfaces or free standing), a foil, a panel
(e.g., molded from the composite material), powder or granular
material (e.g., used as a filling material of hollow panels), or
any structure made completely or to a large extent from the
composite material. Some configurations can include a binding layer
on the surface of the composite material. Some configurations can
include a binding layer in between layers of the composite
material. In addition, or alternatively, an intermediary material
can be included within the composite material in between the
particles.
[0034] In some embodiments, the particles can be sufficiently polar
to hold together by themselves so that for the composite material
no binding layer or intermediary material is needed.
[0035] In some embodiments, the gradient layer structure can be
configured such that a change in particle size between neighboring
layers of the gradient layer structure ranges from 5% to 50% of the
mean particle size. The particle size of neighboring layers can
change by at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or
50%. The particle size of neighboring layers can increase or
decrease. For example, the gradient layer structure can include at
least a first layer with a first particle size smaller than 1 mm
and a second layer with second particle size smaller than the first
particle size.
[0036] In some embodiments, a number of contact points per area
between particles within neighboring layers can change according to
the particle size gradient. The contact points can to some extent
be "potential" contact points in a less densely packed layer.
[0037] In general, a layer includes particles of similar size.
Specifically, a layer (and thus the particles of the layer) is
characterized by a mean particle size. A layer can have generally
any shape and configuration.
[0038] In some embodiments, at least one layer can be a layer of
mono-dispersed particles (herein also referred to as mono-dispersed
layer). The thickness of such a layer can be about the mean
particle size of the particles of that layer. The particles of the
mono-dispersed layer can be densely packed, i.e., most or all of
the particles are in contact with neighboring particles of the
mono-dispersed layer. Alternatively or at least in some regions,
the particles can also be loosely packed thereby providing
available volume in between neighboring particles that can be
filled with other particles.
[0039] In some embodiments, the thickness of at least one of the
layers can be larger than the mean particle size of that layer.
Herein, such a layer is also referred to as a multi-particle layer
and "multi-particle" refers to a thickness given by multiple
particles being positioned along the direction of the cross-section
of the layer. A multi-particle layer can be understood to include
two or more sub-layers each of which correspond essentially to a
layer of mono-dispersed particles. Thus, such a multi-particle
layer has a thickness that is larger than the thickness of a layer
of mono-dispersed particles (of the same type).
[0040] In some embodiments, a multi-particle layer can include two
or more densely packed sub-layers wherein the particles contact
neighboring particles within the sub-layer. Then, the overlap of
neighboring sub-layers is mainly given by the geometry of the
particles. If neighboring sub-layers are loosely packed, sub-layers
can overlap each other to some extent.
[0041] In some embodiments, a multi-particle layer can include two
or more loose packed sub-layers. These sub-layers can overlap in
direction of the cross section of the sub-layers such that the
combined thickness of two overlapping sub-layers is less than twice
the thickness of one sub-layer. In embodiments of overlapping
sub-layers, particles in each sub-layer may not be in contact with
each other but particles of one sub-layer can be in contact with
particles of the other sub-layer. In general, the thickness of the
two sub-layers can be more than the mean particle size of the
particles of the sub-layers and is generally less than twice the
mean particle size of the sub-layers.
[0042] In some embodiments of a multi-particle layer, a layer can
include at least two or more particles in direction of a
cross-section of the layer.
[0043] In some embodiments, the particles within at least one of
the layers can be in contact with each other (or at least being
able to contact each other upon impact of a compression wave). In
addition, the particles of neighboring layers can be in contact
with each other or at least being able to contact each other upon
impact of a compression wave.
[0044] The densely packed particle structure can be configured such
that particles having a size ranges from 5% to 500% of the mean
particle size. The densely packed particle structure can include at
least 25%, 50%, 75%, or 100% core-shell-particles.
[0045] Within the densely packed particle structure, a number of
contact points per area between particles within a region can
change along the cross section according to the size of the
particle.
[0046] The particles of the densely packed particle system can be
arranged in a non-gradient layer structure. At least one of the
layers of the non-gradient layer structure can have a thickness
larger than a mean particle size of the particles of the respective
layer. The at least one layer having a thickness larger than a mean
particle size can be configured to include at least two sub-layers
of particles.
[0047] At least one of the two sub-layers can be densely packed
such that neighboring particles arc in contact with each other
within the at least one sub-layer. At least one of the two
sub-layers is loosely packed such that neighboring particles are
not in contact within the sub-layer. At least one of the two
sub-layers can be loosely packed such that its particles are in
contact with particles of a neighboring layer. At least one of the
two sub-layers can be loosely packed such that its particles are in
contact with particles of a neighboring sub-layer. At least two
sub-layers of particles can overlap partially.
[0048] The thickness of the at least one layer having a thickness
larger than a mean particle size is larger than or equal to about
twice, three-times, four times, five times, six times, seven times,
eight times, nine times, or ten times the mean particle size of the
respective particles of that layer. The thickness of at least one
of the layers of the non-gradient layer structure can be about the
mean particle size of that layer.
[0049] In some embodiments, particles of the gradient layer
structure and/or of the densely packed particle structure can be in
contact with each other.
[0050] In some embodiments, particles of the gradient layer
structure and/or of the densely packed particle structure are
positioned with respect to each other such that at least some of
the particles get into contact with each other during interaction
with a compression wave.
[0051] In some embodiments, particles at least some of the
particles of the gradient layer structure and/or of the densely
packed particle structure are configured for unrestrained
interaction between particles.
[0052] The particles can be configured for unrestrained movement
and therefore interaction upon actuation, e.g., impact of a
compression wave. The particles can be loose and unrestrained to
allow moving and transferring momentum to neighboring
particles.
[0053] The composite material can include, for example, as a layer,
solid particles, hollow particles, core-shell-particles,
microspheres, and spherical particles.
[0054] The gradient layer structure can include at least one layer
with a particle size smaller than 1 mm, 0.1 mm, 0.04 mm, 1000 nm,
500 nm, 100 nm, or 10 nm.
[0055] The particles can provide essentially elastic interactions
between neighboring spheres thereby enabling momentum distribution
when transferring momentum from one of the layers to a neighboring
layer via the particles. The mass of the particles is configured to
allow no delay in reaction to a compression wave.
[0056] The gradient layer structure can include at least one layer
with a mean deviation below about 1%, 5%, or 10% for a median
particle size distribution.
[0057] The particles can be dispersed in a resin that allows
momentum transfer to neighboring particles.
[0058] The gradient layer structure can include an intermediary
material, e.g., for binding particles and/or layers together. The
intermediary material can fill, for example, at least partially a
volume surrounding the particles.
[0059] In some embodiments, the particles attach to each other
without any intermediary material.
[0060] The gradient layer structure and/or of the densely packed
particle structure can include a pore microstructure, which is at
least partially filled with air, gas or an intermediary material.
The intermediary material can be a material of the group consisting
of ionomers, polymers, polymerizable monomers, resins, and
cyclodextrins.
[0061] The gradient layer structure can be a first gradient layer
structure having a first particle size gradient in a first
direction and the composite material further comprises a second
gradient layer structure having a second particle size gradient.
The first and the second gradient can be directed in the same or in
the opposite direction with respect to the layer structure. The
composite material can further comprise a third gradient layer
structure having a third size gradient in the direction of the
first or second gradient structure.
[0062] The multilayer composite material can further include a
substrate and the gradient layer structure or of the densely packed
particle structure can be applied to the substrate. The substrate
can be a housing, e.g., a housing of an electrical device, a
helmet, a helmet liner, a helmet liner pad or pads, a waste
receptacle, a pad, a frame, a wall, a panel, a waste receptacle
liner, a liner, sports equipment such as a racket, a baseball, a
golf ball, a thread, textile, cloth, cladding of a pipe, e.g., for
a pipeline, and the surfaces of vehicles, vessels and crafts for
land, sea, and aviation, side walls of a safety window (e.g., made
of polymer or glass or a combination thereof) etc.
[0063] Materials of the substrate include, for example, substrates
providing a polar surface. Glass, Poly(vinylchloride), nylon,
Poly(methylmethacrylate), Poly(vinylpyridine), and
Poly(vinylphenol) can, for example, provide a polar surface. A
polar surface can, for example, be caused by an acid functionality
at the surface. Some materials can provide a polar surface after a
special surface treatment such as UV irradiation.
[0064] Additionally, various materials can be coated with a polar
coating. An example of a polar coating is a coating that includes
polar particles such as carbon nanoparticles with a phenylsulfonic
acid functionality on their surface.
[0065] Additionally or alternatively, any of the polymers listed
above can be used as coating material.
[0066] The multilayer composite material can be configured as a
self supporting structure. The structure can have the form of a
housing, e.g., housing of an electrical device, a waste receptacle,
a pad, a frame, a wall, a panel, a waste receptacle liner, a liner,
a bag, a foil, sports equipment such as a racket, a baseball, a
golf ball, thread, textile, cloth, a helmet, a helmet liner pad or
pads, a helmet liner, structural components of vehicles, vessels
and crafts for land, sea, and aviation, etc.
[0067] The composite material can be a concentric gradient layer
structure around a center particle. The center particle can be a
core-shell particle. The center particle can be the inner layer of
the concentric layer structure. An outermost layer or an innermost
layer of the concentric layer structure can include particles of a
largest particle size. The layers in a concentric layer structure
can include mono-dispersed layers and/or multi-particle layers as
generally discussed above. Multiple concentric gradient layer
structures can be configured as a coating applied to a substrate or
as a self supporting article. The concentric gradient layer
structure can be attached to and/or applied onto a substrate.
[0068] The composite material can be configured such that a
compression wave propagating in the gradient layer structure is
distorted. An amplitude of a compression wave propagating in the
composite material can be reduced. The composite material can be
configured such that an impact energy of a compression wave
propagating on the gradient layer structure is partially absorbed.
The composite material can be configured such that after reflection
of a shock wave a combined shock wave is reduced in destructive
power. The composite material can be configured to mitigate and/or
remediate a shock wave. The composite material can be configured
such that when impacted by a shock wave, particles of neighboring
layers interact thereby inducing primarily a lateral momentum
transfer due to, e.g., a change in the number in contact
points.
[0069] The multilayer composite material can further include a
core-shell particle layer of core-shell particles having a shell
surrounding a core material. For example, the gradient layer
structure can include such a core-shell particle layer or
core-shell particle. The core-shell particle layer can include one
or more sub-layers of core-shell particles.
[0070] The shells can be configured to release core material when
impacted by a neighboring particle of the composite material, e.g.,
caused by the impact of a compression wave.
[0071] At least one particle can contain a polymeric material such
as urethanes, vinyls, epoxies, phenolics, styrenes, and esters.
[0072] At least one particle can contain on or more of ionomers,
polymers, polymerizable monomers, resins, and cyclodextrins
[0073] At least one particle can contain a fire suppressant of a
group consisting of carbonate, bicarbonate or halide salts, telomer
based materials that incorporate fluorinated materials,
halocarbons, hydrofluorocarbons, hydroxides, hydrates, and
polybrominated materials.
[0074] At least one particle can contain an agent material for
generating a foam, e.g., a polymer foam based on, e.g., urethans,
and styrenes.
[0075] At least one particle can contain a medically active
material such as antibiotics and other medicine for infection,
disinfectants, burn relief agents, materials used for medical
triage treatment and biological/radioactive mitigating and/or
remediative materials.
[0076] At least one particle can be a core-shell material and a
material of the core, when released, is selected to react with at
least one of another core material, a shell material, an
intermediary material, and the material of neighboring
particles.
[0077] Various particles and/or core-shell particles can be
configured to provide a staggered chemical reaction, e.g., when
impacted by a compression wave.
[0078] At least one of the particles can include a radio frequency
(RF) shielding material, such as, for example, copper or nickel,
cemet, and copper or nickel alloys.
[0079] At least one of the core-shell particles can include a shell
material containing a polymeric material such as urethanes, vinyls,
epoxies, phenolics, styrenes, and esters. The shell material can
further include one or more of ionomers, polymers, polymerizable
monomers, resins, and cyclodextrins.
[0080] At least one of the core-shell particles can include a core
material containing a fire suppressant such as carbonate,
bicarbonate or halide salts, telomer based materials that
incorporate fluorinated materials, halocarbons, hydrofluorocarbons,
hydroxides, hydrates, and polybrominated materials.
[0081] At least one of the core-shell particles can include a core
material containing an agent material such as a polymer foam,
urethans, and styrenes.
[0082] At least one of the core-shell particles can include a core
material containing a medically active material such as antibiotics
and other medicine for infection, disinfectant, burn relief agents,
materials used for medical triage treatment, and
biological/radioactive remediative materials.
[0083] At least one of the core-shell particles can include a core
containing a material, when released, to react with at least one of
another core material, a shell material, an intermediary material,
and the material of neighboring particles.
[0084] At least one of the core-shell particles can include a core
containing a material configured, when released, to mitigate and/or
remediate a secondary blast effect of an explosion.
[0085] A core-shell particle can be a free and unrestricted in its
movement.
[0086] The shells can be configured to provide the core material at
a predefined physical condition. For example, the shell can be
configured to rupture at a threshold pressure derived from the
pressure accompanying, e.g., shock waves generated by a blast. The
shell can be further configured to rupture at a specific pressure
caused by the shock wave.
[0087] The core-shell particle layer can further include an
intermediary material configured to evaporate during impact of the
blast wave thereby providing unrestricted movement of the
core-shell particles.
[0088] A position of a core-shell particle layer in a composite
material can define a minimum strength of an impacting compression
wave that is required to initiate the release of the core
material.
[0089] Moreover, core-shell particles can have core material that
change the physical properties of the core-shell particle compared
to a solid particle. For example, gas-filled particles (herein
referred to as hollow particles) can be more deformable than solid
particles and thereby contribute differently to, e.g., the
absorption of shock waves. The structure of the core-shell
particles (shell thickness and/or type of shell material and core
material) may be selected to provide elastic deformable particles
or inelastic (and therefore breakable) particles for respective
stress situations such as impacting shock waves.
[0090] In a transportation device, the composite material can be
configured as at least one of a coating, a film, and a panel
attached, e.g., to an exterior surface. Moreover, the composite
material can be provided within a cavity of a structural component
of the transportation device.
[0091] The composite material can be configured to reduce a
compression wave to provide a predefined threshold pressure at the
core-shell particle layer.
[0092] In some embodiments, the composite material is capable of
absorbing an impact of a shock wave that, for example, is produced
by an explosion or caused during operation of a device. In
addition, or alternatively, in some embodiments, the composite
material is capable of mitigating and/or remediating one or more
secondary blast effects resulting from the explosion.
[0093] In some embodiments, the composite material is suitable for
use in applications that can benefit from a material capable of
interacting with or responding to changes in its surrounding
environment. The interaction and/or response can be designed to be
performed in a controlled and/or predetermined manner. Exemplary
changes in the environment include changes based on variations of
mechanical stress (caused by mechanical load, torsional strain,
vibrations etc.), pressure, temperature, moisture, pH-value,
electric or magnetic fields, and the like.
[0094] Examples of applications can include structural materials,
ceramics, textiles and antiballistic and anti-shockwave materials.
The field of applications can be in civil engineering, aerospace,
automotive applications, military, energy and related
infrastructure, electronics, sensors and actuators, lubricants,
medical applications, and catalysis.
[0095] In particular, one can release catalysts upon actuation of
the composite material, which can then be used to catalyze
materials in various applications. For example, upon impact related
fracture of liners or piping or containers, one can design the
composite material to release materials that contain spills and
clean up via catalysis. Applications include petroleum/oil based
piping systems, chemical containers, and refining operations.
[0096] Additional applications can include shock wave and/or impact
protection of electronic equipment, impact protection in automotive
applications and sports equipment, coatings and claddings for
buildings or oil pipelines (and the like). Oil pipelines, for
example, are confronted with compression waves due to opening and
closing of valves. To mitigate and/or remediate, for example, fire
or leaking from an intentionally destroyed oil pipeline, the inside
surface or the outside surface of the oil pipeline, or both, can
further be provided with fire mitigating layers. This can be done
alternatively or additionally to compression wave absorbing coating
or cladding on the inner or outer surface of the pipeline.
[0097] In some embodiments, the composite material is capable of
reacting to and/or interacting with one or more stimuli existing in
a blast zone environment. For example, in some embodiments the
material can absorb at least a portion of an initial blast impact
and/or pre-over pressure air wave resulting from an explosion. In
addition, or alternatively, the material can be designed to
mitigate and/or remediate one or more related blast effects
resulting from the blast impact itself. Thus, some embodiments can
provide a novel material that through intelligent design of the
material systems can not only reduce blast impact with greater
efficiency and efficacy but that can also mitigate and/or remediate
one or more secondary blast effects.
[0098] In some embodiments, the composite material can provide bomb
blast mitigation and/or remediation by reducing the reflective
value of the bomb blast by absorption of the bomb blast energy. In
some embodiments, the primary mitigating and/or remediating process
can be by absorption of the bomb blast shock wave. In some
embodiments, the mitigating and/or remediating process can be by
absorption of the pre-over pressure air wave that precedes the
shock wave. Absorption of the shock wave and/or the pre-over
pressure wave can occur through one or more mechanisms, including,
for example, momentum transfer, destruction of the spatial symmetry
of, e.g., the blast wave, plastic deformation, rupture of
particles, e.g. filled and unfilled core-shell particles,
restitution, and interparticle/interlayer shear.
[0099] In some embodiments, the composite material can provide a
novel platform from which a wide variety of blast effects can be
mitigated and/or remediated. For example, in a core-shell material
the absorbed energy can be utilized to rupture, e.g., microcapsules
to introduce a series or selection of core materials or material
systems into the blast environment and to thus mitigate and/or
remediate the blast effects. In some embodiments, the composite
material can provide a relatively light weight material that can be
applied to pre-existing structures or systems with no deleterious
effects on the performance attributes of the pre-existing structure
or system.
[0100] In some embodiments, the composite material can offer
proactive mitigation by, for example, comprising RF shielding
materials that can impede and thereby reduce the possibility of a
remote detonation. Furthermore, destructive phenomena can also be
addressed through the composite material including remediative
solutions to chemical, biological, radioactive, optical, sonic,
mechanical failure, and electromagnetic effects.
[0101] In some embodiments, textiles, materials of construction,
and smart and thin film applications can benefit from the composite
material as a multifunctional user defined "smart" material.
Exemplary textile applications can include textiles for use in
firefighting, law enforcement, military, defense, sports, and
fashion. In some embodiments, composite material can be provided in
a form such as a cloth or film suitable for forming uniforms,
helmets and head gear, or being applied thereto when using them as
a substrate that exhibit the beneficial effect of reacting to
environmental changes in a predetermined manner. Exemplary
uniforms, helmets, and head gear can include those protective
uniforms, helmets, and head gear worn by fireman, law enforcement
personnel, and military and/or combat personnel.
[0102] Examples of composite material applications include further
material systems which are designed to utilize latent or introduced
energy to perform a multiplicity of internally predictable actions
utilizing energy from the system as an energy source for inducing
said actions. Applications also exist which utilize the conversion
of impact energy (from physical, optical, acoustic, compression
etc.) to perform a variety of functions including energy conversion
and utilization, actuation of sensors, signals and chemical
reactions in a multi-step systems which can, in concert, perform a
variety of complex user defined functions.
[0103] Some embodiments provide "bomb proof", impact or smart
material applications. Examples of bomb proof applications include
receptacles and liners (waste receptacles and bags etc.),
construction (buildings and their facades, bridges and their
structural members, pipes and pipelines (for fossil fuels,
conduits, utilities), automotive (door panels, bumpers, dashboards,
windshields and windows, undercarriages and roofs), aerospace
(interior/exterior of planes, satellites, helicopters), and high
tech (computer/hardware casings, cable protection).
[0104] In some embodiments, the composite material can be used in
connection with military equipment, structures, vehicles, vessels
and crafts for land, sea, and airborne forces to include armored
and unarmored vehicles, aircraft, (which includes helicopters and
unmanned drones), and nautical vessels such as submarines, ships,
boats and the like.
[0105] For military and civilian uses, the composite material can
be applied as an exterior coating, film, and/or as panel to
pre-existing equipment or, alternatively, can be utilized as a
composite material for forming structural components of the
military vehicle, aircraft, or nautical vessel. Still further, the
composite material can also be utilized to provide shielding of
electromagnetic radiation (RF etc.) in any of the above-mentioned
contemplated applications.
[0106] In some embodiments, the color changing sensor material of
the composite material can be contained in at least one of the
microscale particles, the core-shell particles, an intermediary
material, a material of a binding layer, and a material of a
binding film of the composite material.
[0107] In some embodiments, the color changing sensor material of a
composite material can be configured to change color when exposed
to at least one of gaseous explosive materials, material components
of explosives, materials emitted from an explosive material, vapor
of an explosive material, chemical components outgassed from an
explosive material, and chemical components of an explosive
material. The color changing sensor material can be further
configured to change color when exposed to vapors signaling the
presence of explosive material; either the explosive material
itself or a chemical component of a manufactured explosive.
[0108] In some embodiments, the color changing sensor material of a
composite material can be configured to change color when exposed
to a compression wave.
[0109] In some embodiments, the core-shell particles in the
composite material can include a core containing a material, which
when released, reacts with at least one of another core material, a
shell material, an intermediary material, and the material of
neighboring particles.
[0110] to cause a change in the color of one or more of those
materials. Thereby, a change in the color of the surfaces with
which the sensor material makes contact can occur. In some
embodiments, the released core material modifies the consistency
(e.g., aggregate state) of one or more of the, e.g., shell
material, intermediary material, and material of neighboring
particles. Those modified materials can have features that mark
(e.g., color) a contacting material (e.g., hair in case of using
the composite material within a helmet embodiment). In some
embodiments of the multilayer composite material, the first
substrate can include a polar material to increase the adhesion of
the microscale particles of the layer structure being in contact
with the first substrate.
[0111] In some embodiments, the gradient layer structure can
include a series of gradients having the same direction.
[0112] In some embodiments, the gradient layer structure can
include a series of gradients having varying directions.
[0113] In some embodiments, the core-shell particles can form a
layer of the gradient layer structure.
[0114] The core-shell particles can have a size at the upper end of
the range of particle sizes.
[0115] The multilayer composite material can further include a
second substrate at the second face of the layer structure. The
first substrate, the layer structure, and the second substrate can
be at least partially transparent.
[0116] Certain implementations may have one or more of the
following advantages. Some implementations can absorb the
compression of a bomb blast rather than containing bomb blast
within a receptacle. Absorption is more effective as it reduces the
destructive power of a bomb rather than contains the destructive
power. Some implementations can offer remediation of blast effects.
Some implementations can offer a large selection of other functions
in situ. Functions can be actuated, for example, in real time by
the impinging compression wave. The actuation can be performed at
any time. Some implementations can be applied to existing objects
and structures without changing initial form or function. Some
implementations can be easily augmented to accommodate case
specific responses and can be designed to offer user defined
properties. Some implementations can be tunable to offer user
defined complex and multifunctional performance characteristics.
Some implementations can offer a novel material design approach
capable of engineering directly into the material a predictable
series of responses to an external stimulus, thereby generating a
smart material. Some implementations can enable utilizing and
combining the properties of individual materials in concert or in
series. The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages will be apparent from the
description and drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0117] FIG. 1 is a schematic cross sectional view of a first
composite material with a gradient layer structure having a
decreasing particle size in impact direction.
[0118] FIG. 2 is a schematic cross sectional view of a second
composite material with a gradient layer structure having an
increasing particle size in impact direction.
[0119] FIG. 3 is a schematic cross sectional view of a third
composite material with a plurality of gradient layers structures
as shown in FIG. 1.
[0120] FIG. 4 is a schematic cross sectional view of a fourth
composite material with a plurality of gradient layers structures
as shown in FIG. 2.
[0121] FIG. 5 is a schematic cross sectional view of a fifth
composite material with a plurality of gradient layers structures
as shown in FIGS. 1 and 2.
[0122] FIG. 6 is a schematic cross sectional view of a sixth
composite material with a plurality of concentric particle
layers.
[0123] FIG. 7 is a schematic illustration of blast environment.
[0124] FIG. 8 is a graph of a temporal pressure development in a
shock wave.
[0125] FIG. 9 is a schematic illustration of a reflection of a
shock wave at a seventh composite material.
[0126] FIG. 10 is a schematic illustration of momentum transfer in
a gradient layer structure.
[0127] FIG. 11 is schematic illustration of an exemplary core-shell
particle.
[0128] FIG. 12 is a schematic cross sectional view of a planar
layer structure of mono-dispersed core-shell particles on a
substrate.
[0129] FIG. 13 is a schematic cross sectional view of a planar
gradient layer structure including a core-shell particle layer.
[0130] FIG. 14 is a schematic cross sectional view of a concentric
gradient layer structure surrounding a core-shell particle.
[0131] FIG. 15 is a schematic cross sectional view of a container
coated with a composite material as shown in FIG. 1.
[0132] FIG. 16 is a schematic cross sectional view of a fiber
coated with a composite material as shown in FIG. 1.
[0133] FIG. 17 is a schematic cross sectional view of a fiber
coated with a composite material as shown in FIG. 12.
[0134] FIG. 18 is a perspective view of a pipeline.
[0135] FIG. 19 is a perspective view of a hand held device.
[0136] FIG. 20 is a schematic illustration of a compression wave
deformation in a gradient layer structure.
[0137] FIG. 21 is a cross section through a helmet with helmet
liner pads, and a helmet liner.
[0138] FIG. 22 is a schematic cross sectional view of an exemplary
structure of microscale particles for a helmet liner pad.
[0139] FIG. 23 is a schematic representation of a transportation
device provided at least partly with a composite material.
[0140] FIG. 24 is a schematic cross sectional view of an exemplary
waste receptacle made from a multilayer composite material.
[0141] FIG. 25 is a schematic cross sectional view of a composite
material with a gradient layer structure illustrating
multi-particle layers.
[0142] FIG. 26 is a schematic cross sectional view of a composite
material with a gradient layer structure illustrating an
alternating gradient direction.
[0143] FIG. 27 is a schematic cross sectional view of a composite
material illustrating multi-particle layers with concentric
particle layers.
[0144] FIG. 28 is a schematic cross sectional view of a composite
material illustrating multi-particle layers with concentric
particle layers.
[0145] FIG. 29 is a schematic cross sectional view of a composite
material with planar multi-particle layers on a substrate.
[0146] FIG. 30 is a schematic cross sectional view of a composite
material with planar multi-particle layers forming a
uni-directional gradient.
[0147] FIG. 31 is a schematic cross sectional view of a composite
material with planar multi-particle layers forming a gradient with
changing direction.
[0148] FIG. 32 is a schematic cross sectional view of a composite
material with planar multi-particle layers forming a gradient
alternating in direction.
[0149] FIG. 33 is a plot of the particle size over the layers of a
gradient structure.
[0150] FIG. 34 is a plot of the particle size over the layers of a
gradient structure.
[0151] FIG. 35 is a plot of signals of an impact tester for various
assemblies.
[0152] FIG. 36 is a scanning electron microscope image of a
composite material.
[0153] FIG. 37 is a scanning electron microscope image of a cross
section of the composite material of FIG. 36.
[0154] FIG. 38 is a scanning electron microscope image of a
composite material.
[0155] FIG. 39 is a scanning electron microscope image of a cross
section of the composite material of FIG. 38.
[0156] FIG. 40 is a plot of a depth-dependent hardness of a surface
of a composite material.
[0157] FIG. 41 is a plot of a depth-dependent hardness of a surface
of a composite material.
[0158] FIG. 42 is a schematic representation of a safety glass with
a composite material in a sandwich structure.
[0159] FIGS. 43 to 48 are schematic plots of particle sizes
distribution of the layers of a composite material.
[0160] FIGS. 49 to 54 are schematic plots of particle sizes
distribution of the layers of a composite material based on solid
and core-shell particles. FIG. 55 is a schematic cross sectional
view of a densely packed particle structure.
[0161] Like reference symbols in the various drawings may indicate
like elements.
DETAILED DESCRIPTION
[0162] In some aspect, the invention relates to an engineered
composite material that is based on a structure of particles with a
gradient layer structure having different particle sizes in
neighboring layers and a densely packed particle structure that has
essentially no restriction to the distribution of the particle size
over the cross section.
[0163] For the gradient layer structure, the layers can be arranged
to have a (constant or varying) gradient of the particle sizes,
e.g., increasing, decreasing, or alternating particle size.
[0164] In contrast, the densely packed particle structure is a
non-gradient particle structure with, for example, particles of a
single size only, or particles of two sizes. The particles of the
densely packed particle structure can be arranged in monolayers or
layers a few particles thick, thereby forming a densely packed
layer structure of the particles. Such a layered densely packed
particle structure can be generated, for example, layer by layer.
In addition, a densely packed particle structure can also be
generated as a bulk, e.g., by drop coating.
[0165] A densely packed particle structure is described in more
detail, for example, in PCT patent application, filed on even date
herewith and entitled "DENSELY PACKED PARTICLE STRUCTURE" by Z. R.
Greenhill, Y. C. Avniel, and J. J. BelBruno, the contents of which
is hereby incorporated by reference in its entirety.
[0166] Such a gradient layer structure can be capable of absorbing,
for example, the energy of an explosion, pressure waves, sound
waves, shock waves, and compression waves. In general, the layers
of the composite material, e.g., of the gradient layer structure or
a layered densely packed gradient structure, can be mono-dispersed
layers or multi-particle layers, i.e., a layers that have a
thickness given by a single (mono-dispersed layer) or multiple
particles (multi particle layer) being positioned along the
direction of the cross-section of the layer. Within a
multi-particle layer, the particle size is essentially
constant.
[0167] A specific situation occurs for a multi-particle layer
within a gradient layer structure, Then, the interaction between
same size particles takes place in addition to interaction between
different size particles. This interaction is similar to the
interaction between particles of the densely packed particles
having the same size. Depending on the numbers of layers, one may
consider those multi-particle layers a separate unit of a densely
packed particle structure sandwiched between to gradient layer
structures. In general, one can in general consider multi-particle
layer structures of approximately the same thickness, number of
layers, or efficiency as, the gradient layer structure to be a
densely packed particle structure. Multi-particle layers of smaller
size, number of layers, or efficiency than the gradient layer
structure can be considered to be part of the gradient layer
structure.
[0168] Examples of gradient layer structures and/or densely packed
particle structures are discussed, for example, in connection with
FIGS. 1 to 6, 9, 13 to 24, 43 to 55. The physical environment
generated by a bomb blast is discussed below in connection with
FIGS. 7 and 8, and a potential explanation for the effect of the
invention is discussed in connection with FIGS. 9 and 10. The
presented gradient layer structures and/or densely packed particle
structures can provide an increased lateral momentum and energy
transfer during propagation of an incident wave. For example, when
gradient layer structure and/or a densely packed particle
structures are subjected to the impact of a blast, the shock wave
from the blast travels across the structures, and it is assumed
that the shock wave is increasingly deflected in different
directions by, e.g., the alternating amount of contact points
within neighboring layers.
[0169] In such multilayer composite materials, the particle size
can range from about 1 nm to several millimeters, for example, from
150 nm to 1 mm. The material of the particles can comprise, e.g.,
(porous) silica; aluminum hydroxide; polymeric materials; metal
spheres, and ceramics. As shown specifically in FIGS. 3 to 5, a
composite material can include several layer structures with
identical or reversed direction of the gradient and sections of no
gradient. The layers can be planar or have a specific shape.
Moreover, the structures can be applied to a substrate having a
specific shape, see FIG. 3. Alternatively, the structures can be
concentric as for example described in connection with FIG. 6.
[0170] While most of the drawings shown herein illustrate a layer
just by a string of single particles, any of the layers shown
herein can in general be a layer of mono-dispersed particles or a
multi-particle layer having more than one sub-layer (a sub-layer
itself being, for example, a dense mono-dispersed particle layer).
Examples are described in connection with FIGS. 25 to 32, which
show composite materials that include gradient layer and densely
packed particle structures based on layers of mono-dispersed
particles and multi-particle layers. In the drawings, densely
packed particle structures are often illustrated as a single layer
but are in general multilayer structures or non-layered structures
having the thickness of the size of several particles.
[0171] In some aspects, a composite material includes core-shell
particles having a core surrounded by a shell. The core can be
partly or completely filled with solid, liquid, gasous, and/or
gel-like material. Depending on the specific application, the shell
materials of the core-shell particles can be configured to be
pliable during interaction with a compression wave, thereby
attenuating the compression wave in addition to any structural
attenuation effect of several particles. The attenuation effect of
a core-shell particle depends on the material of the shell (e.g.,
its elasticity) and the physical properties of the core material. A
gas filling of a so called hollow core-shell particle (or a partly
with a solid filled core-shell particle) will itself essentially
not contribute to the physical properties of the core-shell
particle, while a complete solid or liquid filling can modify the
physical properties of the core-shell particle.
[0172] In some aspects, a composite material includes core-shell
particles such as filled microspheres, see FIG. 11 that are
"filled" with one or more application specific materials within one
or more core-shell particles. Depending on the specific
application, the shell materials of the core-shell particles can be
configured such that given a specific physical pressure, the core
material is released. In exemplary embodiments, the composite
material can include a mono-layer of mono-dispersed core-shell
particles or a layer having a thickness of multiple core-shell
particles (multi-core-shell particle layer with more than one
sub-layer). Exemplary materials for the core can include for fire
suppression materials such as potassium bicarbonate, aluminum
and/or magnesium hydroxide; for energy absorption porous silica,
silica, and/or Perlite; and for RF shielding copper, and/or
nickel.
[0173] In some applications, the physical properties of core-shell
particles are essentially determined by the shell and the filling
(core-material) is, for example, a gas, a gas-liquid mixture, or a
gas-gel mixture, or a gas-solid mixture, which does not or only to
some extent contribute to the interaction with, for example, a
pressure wave.
[0174] Moreover, in some aspects, the core-shell particle layer can
be combined with a gradient layer structure as discussed, for
example, in connection with FIGS. 13, 14, 17, 22, and 24. In
general, throughout the composite material one or more
mono-dispersed layer of core-shell particles and/or one or more
multi-core-shell particle layers can be provided.
[0175] In various applications, the composite materials based on
gradient layer structure and densely packed particle structure with
or without core-shell particles can be applied to devices such as
containers as shown in FIGS. 15 and 24 as examples for waste
receptacles. The composite material can further applied to fibers
and used in connection with textiles as discussed in connection
with FIGS. 16 and 17. Exemplary textile applications can include
textiles for use in firefighting, law enforcement, military,
defense, sports, and fashion. Such cloth or film can be suitable
for forming uniforms, helmets, helmet liners, helmet liner pads
etc. that exhibit the beneficial effect of reacting to
environmental changes in a predetermined manner. Specific examples
can include inner liners for uniforms or jackets that are either
attachable or fused into the cloth.
[0176] Additional applications can involve the suppression of
compression waves (including shock waves) in pipes. Shock waves
are, for example, generated through valve operation in oil
pipelines as discussed in connection with FIG. 18. The composite
material can further be applied to surfaces that require impact
resistance. Examples include housing of hand held devices, helmets,
vehicles or components thereof, as discussed in connection with
FIGS. 19, 21 to 24. The composite material in those applications
can be applied as a coating (e.g. film) or provided as a liner. The
composite material can further be used in connection with cushions,
for example, the helmet pads shown in FIG. 21. Additional
applications can involve the suppression of compression waves to
make wall structures or windows safer.
[0177] In general, for composite material in applications, which
require a minimum transparency, the material and the size of the
particles can be selected appropriately. In general, particle sizes
below about 200 nm can enhance the transparency. For example, 30-50
layers of silica particles of 200 nm size is transparent.
[0178] The composite material can be generally comprised of a
plurality of adjacent layers whereby each layer is comprised by a
plurality of particles having a predetermined median particle size
diameter. In gradient layer structures, the predetermined median
particle size of each adjacent layer (be it a layer of
mono-dispersed particles or a multi-particle layer), when viewed in
cross section, forms a particle size gradient such that median
particle size of each layer sequentially decreases (or increases)
across the cross section of the material. The particle size
gradient is accompanied by an inverse "gradient" in the amount of
contact points per unit of area. For example, a decreasing particle
size within the gradient layer structure results in an increase of
particle surface contact points per unit of area because more
particles interact in each adjacent layer. Similarly, an increasing
particle size within the gradient layer structure results in a
decrease of particle surface contact points per unit of area
because less particles interact in each adjacent layer. A gradient
layer structure can, in general, include changes in the gradient,
i.e., in the steepness of the change of the particle size and the
direction of the change in the particle size.
[0179] In contrast to the gradient layer structure, densely packed
structures may have a constant number of particles and therefore,
amount of contact points. In general, allowing random particles
size distributions, also the number of particles and contact points
changes randomly. In practice, the random particle size
distribution is, however, restricted by the particles provided and
controlled during the manufacturing.
[0180] The size of the particles forming the surface of the
composite material or the side of the composite material that
interacts with an incoming distortion can additionally influence
the physical properties of the composite material. The influence on
the surface hardness is discussed below, for example, in connection
with Example 7.
[0181] Herein various aspects are discussed for layer structures,
even though similar considerations are also applicable for a
non-layered densely packed particle structures.
[0182] The plurality of adjacent layers are configured such that
the proximity of the particles within the various layers and the
proximity of particles from one adjacent layer to another adjacent
layer are sufficiently close to one another to allow a transfer,
dissipation, and/or conversion of energy to take place when the
gradient layer structure is subjected to the impact energy from,
for example, a blast. Specifically, a momentum transfer response
only occurs when the particles are touching and compressed. Once
the contact between particles is not possible, the particles can
become an amalgamation of independent systems which in themselves
interact as a multitude of systems.
[0183] FIG. 1 shows a schematic cross-sectional view of an
exemplary composite material 100. The direction of an impact, e.g.,
the compression wave of a blast, is indicated through arrow 105 and
is directed toward a surface of a composite material 100. The
composite material 100 includes a plurality of adjacent layers
110-170. Each of the layers 110-170 of the material includes
particles p1-p7 having a predetermined median particle size
dp1-dp7, respectively. The relative particle size distribution with
respect to the median particle size dp1-dp7 of the particles p1-p7
within any given layer 110-170 is small. For example, the
coefficient of variation is below 20%, or below 10%, or even below
5%.
[0184] With respect to the gradient structure, each layer of the
composite material 100 can be distinguished from the adjacent layer
or layers by the difference in particle sizes contained therein.
Additionally, within each of the layers 110-170 of FIG. 1, particle
surface contact points cp1-cp7 between particles of each of the
layers 110-170 are indicated. As can be easily seen, the smaller
the particle the more contact points per unit of area.
[0185] In FIG. 1, the particle sizes of each adjacent layer form a
particle size gradient and satisfy the relationship
dp1>dp2>dp3>dp4>dp5>dp6>dp7. It should be
understood that the specific median particle sizes selected for a
given layer of the material are not as critical as long as a
desired particle size gradient is provided.
[0186] The gradient can be expressed as the change in size of the
particle diameters populating individual layers. For example, the
particle diameters can shrink (or increase) progressively by a
factor spanning the range of 5% and 50%. The shrinking or
increasing can be linear or non-linear.
[0187] In direction of a decreasing median particle size, the
median particle size of the adjacent layers 110-170 can be chosen
such that number of particle surface contact points cp1-cp7 per
unit area increases at least by one. For example, if one of the
layers 110-170 has n particle surface contact points then the
neighboring layer having a smaller particles has at least n+1
particle surface contact points per unit area. Accordingly, the
number of particle surface contact points fulfills the relation:
cp7>cp6>cp5>cp4>cp3>cp2>cp1.
[0188] Microscale particles (e.g. sub-millimeter size particles)
can be used to manufacture the composite material and the selection
of the size, at least in part, is dependent upon the desired end
use application for the composite material. For example, the
particle sizes can be less than about 1,000 .mu.m in size, less
than about 500 .mu.m, less than about 250 .mu.m, or even less than
about 125 .mu.m. Particle size down to the single nanometer scale
can be applied.
[0189] In case of the composite material 100 of FIG. 1, the
particles of layer 110 can have a relative median particle size of
about 150 .mu.m, the particles of layer 120 can have a relative
median particle size of about 75 .mu.m, the particles of layer 130
can have a relative median particle size of about 40 .mu.m, the
particles of layer 140 can have a relative median particle size of
about 10 .mu.m, the particles of layer 150 can have a relative
median particle size of about 2 .mu.m, the particles of layer 160
can have a relative median particle size value of 0.75 .mu.m and
the particles of layer 170 can have a relative median particle size
value of 0.15 .mu.m.
[0190] The example of FIG. 1 has seven layers. However, it should
also be understood that the plurality of layers can comprise less
or more layers, for example three or more layers. Examples for the
number of layers in a composite material having a gradient in the
particle size can include less than seven layers (e.g., two, three,
four, five, six), or more layers (e.g. at least ten, twenty,
thirty, forty layers). Table 1 shows example layer structures for a
gradient of 5% to a gradient of 50% starting at a maximum particle
size of 40 .mu.m and having up to 40 layers within a gradient layer
structure. The indicated median particle sizes decrease layer by
layer 5%, 10%, . . . 50%. For a gradient of 20%, two layer
structures are shown having 20 or 28 layers. Example polymeric
particles can include monodisperse polystyrene microspheres and
Polybead.RTM. Hollow Microspheres. Additional particles and
particle materials are discussed below.
TABLE-US-00001 TABLE 1 Gradient 5% 10% 20% 20% 25% 40% 50% Layer 1
40.00 40.00 40.00 40.00 40.00 40.00 40.00 Layer 2 38.00 36.00 32.00
32.00 30.00 24.00 20.00 Layer 3 36.10 32.40 25.60 25.60 22.50 14.40
10.00 Layer 4 34.30 29.16 20.48 20.48 16.88 8.64 5.00 Layer 5 32.58
26.24 16.38 16.38 12.66 5.18 2.50 Layer 6 30.95 23.62 13.11 13.11
9.49 3.11 1.25 Layer 7 29.40 21.26 10.49 10.49 7.12 1.87 0.63 Layer
8 27.93 19.13 8.39 8.39 5.34 1.12 0.31 Layer 9 26.54 17.22 6.71
6.71 4.00 0.67 0.16 Layer 10 25.21 15.50 5.37 5.37 3.00 0.40 0.08
Layer 11 23.95 13.95 4.29 4.29 2.25 0.24 Layer 12 22.75 12.55 3.44
3.44 1.69 0.15 Layer 13 21.61 11.30 2.75 2.75 1.27 0.09 Layer 14
20.53 10.17 2.20 2.20 0.95 Layer 15 19.51 9.15 1.76 1.76 0.71 Layer
16 18.53 8.24 1.41 1.41 0.53 Layer 17 17.61 7.41 1.13 1.13 0.40
Layer 18 16.72 6.67 0.90 0.90 0.30 Layer 19 15.89 6.00 0.72 0.72
0.23 Layer 20 15.09 5.40 0.58 0.58 0.17 Layer 21 14.34 4.86 0.46
0.13 Layer 22 13.62 4.38 0.37 0.10 Layer 23 12.94 3.94 0.30 Layer
24 12.29 3.55 0.24 Layer 25 11.68 3.19 0.19 Layer 26 11.10 2.87
0.15 Layer 27 10.54 2.58 0.12 Layer 28 10.01 2.33 0.10 Layer 29
9.51 2.09 Layer 30 9.04 1.88 Layer 31 8.59 1.70 Layer 32 8.16 1.53
Layer 33 7.75 1.37 Layer 34 7.36 1.24 Layer 35 6.99 1.11 Layer 36
6.64 1.00 Layer 37 6.31 0.90 Layer 38 6.00 0.81 Layer 39 5.70 0.73
Layer 40 5.41 0.66
[0191] In Table 1, a constant gradient of 5% is given. However, one
could alternatively vary the gradient. For example, a gradient
layer structure can include the layers 1 to 7 with a gradient of
25%, followed by layers 35 to 40 with a gradient of 5%.
Additionally, that gradient layer structure can include layers 11
to 28 with a gradient of 25%.
[0192] Additionally, a composite material can have a layer
structure that includes a series of repeating layer sequences
wherein the order of layers within a layer sequence can be inverted
and/or the layers of a sequence can be modified.
[0193] For example, as shown in FIG. 1, any one of the layers
110-170 can include a mono-dispersed layer of particles p1-p7 and
thus has a thickness approximately equal to the median particle
size diameter of the particles p1-p7 within that layer 110-170,
respectively. Then, composite material 100 would be pure gradient
layer structure. Alternatively, any one or more layers can also be
comprised of a plurality of sub-layers of the particles forming a
multi-particle layer. Then, the thickness of a given layer can
optionally be greater than the median particle diameter size of the
particles within a given layer of the system. Specifically, layers
with smaller particles can include, for example, more than one
particle, e.g., up to 20 particles.
[0194] As any of the layers 110-170 can, in principle, be a
multi-particle layer and therefore be considered a densely packed
particle structure. For example, the largest particles of layer 100
can include 10, 20, 30, 40, or 50 layer of the same size. A
corresponding particle size distribution is shown in FIG. 43.
[0195] Additionally (or alternatively), layer 170 of the smallest
particles can be formed as a densely packed particle structure. A
corresponding particle size distribution is shown in FIG. 44.
[0196] Alternatively (or additionally), one of the inner layers,
e.g., layer 140 can be formed as a densely packed particle
structure. A corresponding particle size distribution is shown in
FIG. 45.
[0197] As further shown in FIG. 1, the energy from a blast impact
105 is directed initially toward the first layer 110 which is
comprised of a plurality of particles having the largest median
particle sizes. Thus, the energy of the blast impact will then
propagate though the material in the direction of largest particle
size to smallest particle size, i.e., from layer 110 toward layer
170.
[0198] As used herein, the terms "nano" and "nanoscale" particles
generally refer to particles having a size on the scale of
nanometers, such as, for example, particles having at least one
aspect equal to or less than about 100 nm. As used herein, the
terms "macro" and "macroscale" particles generally refer to
particles larger than nanoscale, preferably particles having at
least one aspect greater than about 100 nm, or more preferably
particles having at least one aspect greater than about 500 nm. As
used herein, the terms "meso" and "mesoscale" particles generally
refer to particles having aspects between nanoscale and macroscale
systems. As used herein, the terms "micro" and "microscale"
particles generally refer to particles from the nanoscale to
particles having at least one aspect in the order of thousand
micrometers, e.g., in the range of 0.1 nm to 1000 .mu.m.
[0199] It should be noted that these sizes and ranges can vary
and/or overlap and that therefore the definitions provided herein
are intended only to serve as a general guide and not to limit the
various embodiments. Nanoscale particles can often exhibit
different properties than corresponding macroscale analogs.
Mesoscale particles can often exhibit properties that can be
attributed to both nano and macro systems.
[0200] In some embodiments, the composite material includes
macroscale particles, mesoscale particles, and/or nanoscale
particles, such that the energy that is dissipated (e.g. frictional
energy) can be increased. In some embodiments, combinations of
mesoscale and/or nanoscale particles achieve application specific
mechanical properties and the amount of dissipated energy can be
increased.
[0201] In a composite material, frictional energy dissipation can
be increased by populating space devoid of macroscale (large)
particles with nanoscale and/or mesoscale (small) particles. The
choice of particle size used is a function of a particle size
gradient, material composition, and desired properties. The small
particles can also be used to adjust the materials mechanical
properties (e.g. mechanical strength). In addition, or
alternatively, the small particles can introduce further material
systems that can be beneficial upon actuation of the system, e.g.
by a bomb blast.
[0202] It should also be understood that the composite material is
not limited only to configurations whereby the layer comprising the
largest median particle size forms the surface layer and therefore,
receives the initial energy of, e.g., the impact from a blast. For
example, as shown in FIG. 2, a composite material 200 can also be
formed to comprise the reversed particle size gradient, wherein the
first layer to receive the impact energy from the blast is layer
270. According to this embodiment, the energy of the blast impact
will propagate though the material along a direction 205 from the
smallest particle size to the largest particle size, i.e., from
layer 270 toward layer 210. In the structure of FIG. 2, the
gradient has the opposite direction to the gradient of FIG. 1 and
accordingly, the number of contact points decreases for layers
being further away from the surface subjected to the impact.
[0203] In some embodiments, a plurality of the above described
materials can be stacked or arranged sequentially one upon the
other. For example, as shown in FIG. 3, a composite material
sequence 300 includes a plurality of composite materials 100 (large
to small particle size gradient as discussed in connection with
FIG. 1) can be stacked or arranged sequentially on top of a
substrate 310. Specifically, FIG. 3 shows five composite materials
100. To this end, it should be understood that any desired number
of the layer sequence as shown for the composite materials 100 can
be stacked or arranged in sequence.
[0204] Likewise, as shown in FIG. 4, a composite layer sequence 400
includes a plurality of layer sequences as shown for the composite
material 200 (small to large particle size gradient as discussed in
connection with FIG. 2) can be stacked or arranged sequentially.
Once again, it should be understood that any desired number of
layer sequences can be stacked or arranged in sequence. A larger
number of gradient layer structures and gradient layers can provide
self standing structures, while fewer layers or gradient layer
structures can provide a flexible composite material that can be
applied to structured surfaces. In FIG. 4, a substrate is not
explicitly shown, thereby indicating a self standing structure.
However composite layer sequence 400 can alternatively be attached
to a substrate, for example at the large particle side.
[0205] In some embodiments, and as shown in FIG. 5, a plurality of
the composite materials 100 and 200 can be stacked or arranged in
an alternating or staggered arrangement to form a composite
material 500 so that the interface of two adjacent materials 100
and 200 can comprise either a divergence or a convergence of
particle size gradients. Once again, it should be understood that
according to this embodiment, any desired number of the composite
materials 100 and 200 can again be stacked or arranged in the
manner as described. While in FIG. 5 larger particles form the
surface, one can alternatively form the gradient structure such
that the smallest or medium size particles form the surface (see,
e.g., FIG. 31). Opposing surfaces of a composite material can also
be provided with different size particles.
[0206] As illustrated in FIGS. 1 to 5, the composite material can
be provided as a plurality of substantially parallel or sequential
layers which can, for example, be attached, applied or deposited
sequentially onto a substrate. However, in some embodiments and as
shown in FIG. 6, the plurality of layers can be oriented
concentrically, thereby forming a concentrically layered particle
600. The concentrically layered particle 600 includes a central
particle 610 that is surrounded by a plurality of concentric
layers, only two layers 620 and 630 are shown but many more could
be applied. The concentric layers are each comprised of particles
of decreasing size as the layers extend farther from the central or
core particle 610. As exemplified in FIG. 6, the central particle
610 has a predetermined particle size dp1. First outer concentric
layer 620 is comprised of a plurality of particles having a median
particle size dp2 that is less than the dp1. The second outer
concentric layer 630 is comprised of a plurality of particles
having a median particle size dp3 that is less than dp2. Once
again, although this embodiment has been exemplified in FIG. 6 as
having the central particle 610 surrounded by two concentric
particle layers 620 and 630, it should be understood that any
number of concentric particle layers can be applied and a central
particle is not required and could be replaced by free space or a
few contacting inner particles.
[0207] As discussed above for the embodiments of FIGS. 1-5, the
direction of the gradient can be reversed or different types and/or
directions of gradients can be used within a gradient
structure.
[0208] Similarly, in the above discussion, one or more layers
(except the core particle 610 can be the densely packed particle
system. In a respective discussion of FIGS. 43 to 54, consider the
layer number extends then in radial direction, while in planar
embodiments the layer number extends along the cut through the
layer structure.
[0209] It should be appreciated that one advantage of the
concentrically layered particles 600 is its potential ease of large
scale application. In particular, a plurality of the individual
concentrically layered particles 600 can be suspended in a medium
and subsequently applied onto a desired substrate. This technique
can thus enable the generation of a product with desired energy
absorption effect that is based on a single application of
concentrically layered particles 600 rather than on a plurality of
successive applications of the in order to provide the different
layers such as, e.g., the layers 110-170 of composite material
100.
[0210] The individual layers which are populated by the different
sized particles have a number of distinct attributes. In some
embodiments, the layer thickness can at least for the layers of
larger particles be as close as possible to the particle diameter,
while for layers of smaller particles multi-particle layers may be
applied having a thicknesses of, e.g., 2-20, 5-15, and 7-12
particles, e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 particles. As
discussed above, one can in general consider multi-particle layer
structures of approximately the same thickness, number of layers,
or efficiency as the gradient layer structure to be a densely
packed particle structure. Multi-particle layers of smaller size,
number of layers, or efficiency than the gradient layer structure
can be considered to be part of the gradient layer structure.
[0211] The particles within the layers can be in a densely packed
structure, thereby providing a high number of contact points
between the particles or particles after being moved only for a
short distance (e.g. less then the particle size).
[0212] The composite material can be used to mitigate and/or
remediate the damage of high intensity compression waves, such as
shock waves caused be an explosion. While not wishing to be bound
by theory, several mechanisms are presented which are assumed to be
responsible for the mitigating features of the composite
material.
[0213] When an explosive device detonates, it can impact the
surrounding environment, in particular the blast zone, through
various distinct ways. In particular, as shown in FIG. 7, the
explosion of a bomb 10 results in an initial bomb blast with a
shock wave 20 of high pressure, i.e., a compression wave, followed
by a low pressure zone 30.
[0214] The bomb blast can be viewed as a three dimensional wave
emanating from the origin of the bomb blast. The leading edge of
the blast wave exhibits a nearly discontinuous increase in
pressure, density and temperature. The transmission of a bomb blast
through a medium is inherently a nonlinear process and can be
described by nonlinear equations of motion. Considering an ideal
bomb blast produced from a spherical and symmetric source and
propagated in a still and homogenous medium, the resulting bomb
blast will also be perfectly spherical and therefore the
characteristics of the blast wave are functions of a distance R
from the center of the source and the time to travel a distance
t.
[0215] As shown in FIG. 8, the pressure changes across the shock
wave 20 and the low pressure zone 30. Prior to the impact of the
shock wave 20, at a given point, the pressure is equal to the
ambient pressure p.sub.0. At a time t.sub.a that coincides with the
arrival of the shock front, the pressure rises discontinuously to a
peak pressure of p.sub.0+P.sub.s.sup.+ (over-pressure 800 in the
shock wave zone 20). The pressure then decays to ambient pressure
in a total time t.sub.a+T.sup.+, drops to a reduced pressure
p.sub.0-P.sub.s.sup.- (under-pressure 810 in the low pressure zone
30), and eventually returns to ambient pressure p.sub.0 in a total
time t.sub.a+T.sup.++T.sup.-.
[0216] When compression of a medium exceeds the ability of thermal
motion to dissipate the energy, the over-pressure 800 occurs. The
peak pressure p.sub.0+P.sub.s.sup.+ of the over-pressure 800 can be
correlated to the damage produced from the explosion and is
considered a primary source of bomb related injuries. Through
increasing the over-pressure 800, the reflection of a blast wave
from a surface can magnify its destructive power several times. For
example, when the shock wave 20 impacts upon a solid surface, it
can reflect off the surface and increasing up to nine times in
destructive power. Thus, being able to control the reflection of
the blast wave based, for example, on coatings of the composite
material can allow reducing the destructive power.
[0217] The explosion can further result in the formation of a fire
ball 40, which trails the blast. Additional secondary blast effects
can present distinct threats to life, limb, and property. For
example, radioactive materials can cause significant health issues
to victims initially impacted by a detonation, along with
individuals who later come into contact with blast victims and/or
materials exposed to radioactive materials. Chemical agents, such
as, for example, nerve, blister, blood, and choking agents, can be
released into the environment causing poisoning in people and the
environment. Biological materials and/or biological toxins (e.g.,
Bacillus anthracis), viral agents (e.g., SARS and smallpox),
biological toxins (e.g., ricin), or other types of biological
materials (e.g., Q fever) can incapacitate, kill, or contaminate
the environment.
[0218] In the case of electromagnetic weaponry, humans can suffer
tissue damage, and electronic systems can suffer irreversible
damage. Sonic blasts can rupture living tissue, destroy hydraulic,
electronic, and mechanical systems and can propagate large
distances from the initial blast source. In addition, other
substances can cause a plethora of destructive responses by, for
example, malicious intent or natural tendency. Although not shown,
another blast effect is caused by accelerating particulate material
and shrapnel that can also result from the force of the blast.
[0219] As described below in connection with, for example, FIGS.
11-24, an embodiment of a composite material can be configured to
mitigate and/or remediate one or several of those secondary blast
effects.
[0220] While not wishing to be bound by theory, several mechanisms
are explained in connection with FIGS. 9 and 10. As illustrated in
FIG. 9, the mechanisms are considered to contribute to the
reduction of the destructive power of a shock wave 910 when
reflected from a composite material 900 with a gradient layer
structure. Exemplary mechanisms include energy absorption, wave
dispersion, and braking of the wave symmetry.
[0221] While in FIGS. 9 and 10 essentially gradient layers are
shown, it is noted that the densely packed particle structure can
be based, for example, on one or more of the indicated layers. In
addition, while most of the discussion of the densely packed
particle structure refers to layers, similar considerations can
most of the time be performed for non-layered structures.
[0222] In FIG. 9, a reflected shock wave 920 is illustrated to have
a reduce amplitude corresponding to an energy absorption mechanism
during reflection. The energy absorption can be based on internal
friction (due to shear forces between the layers), inelastic
interaction between particles, and/or the breaking of particles or
particle shells.
[0223] In addition, the reflected shock wave 920 can be stretched
in time (as shown), e.g., dispersed due to a modified momentum
transfer mechanism based on the gradient structure and/or densely
packed particle structure as discussed in connection with FIG. 10.
The propagation of the shock wave in the direction of arrow 1005
through a gradient layer structure 1000 depends specially and
temporally on the momentum transfer between the particles, e.g., of
the various layers of the gradient layer structure 1000. As
indicated in FIG. 10 through double arrows 1020, momentum can be
transferred between particles of the same layer. A momentum
transfer between particles of neighboring layers is in general not
parallel to the propagation direction of the shock wave through the
composite material. Arrows 1030 indicate the momentum transfer
direction between particles of neighboring layers, which is given
through the contact points of those particles. Thus, the momentum
associated with the impacting shock wave can be redirected and then
partially absorbed within the layers. Based on the large number of
contact points and momentum transfer events, the increased particle
numbers in the layers with the smaller particles are assumed to
contribute to the reduction in energy.
[0224] Moreover, as explained in connection with FIG. 20 the
symmetry of a wave front 2000 of, e.g., a shock wave can be
distorted during propagation within a composite material 2005 along
a direction 2010 of propagation. FIG. 20 shows a sequence of
schematic illustrations of the wave front 2000 at four positions
within the composite material 2005. Four schematic drawings 2006,
2007, 2008, and 2009 of the composite material 2005 illustrate
additionally the location of four increasingly distorted wave
fronts 2001, 2002, 2003, and 2004. Layers with black spheres
correspond to the position of the wave front within the gradient
layer structure 2005.
[0225] As shown in FIG. 20, the incident wave front 2000 is assumed
to be essentially a planar wave that is well defined and has a
large amplitude (shock wave). In FIG. 20, the magnitude of the
amplitude is illustrated by the thickness of the lines representing
the wave front.
[0226] Within the composite material 2005, the wave front of the
compression wave becomes distorted. Specifically, when interacting
with particles of various sizes of the various layers of the
gradient layer structure 2005, and, in particular, when advancing
from one layer to another, the planar form of the wave front is
distorted.
[0227] For example, and while not wishing to be bound by theory, at
some locations in the plane of the wave front, the shock wave
propagates slower than at others. For a first layer 2011 of the
gradient layer structure 2005, the upper and lower parts of the
wave front 2001 are delayed. Thus, in the first layer 2011, the
spatial extent of the compression wave in the direction 2010 of
propagation increases to a spreading A.
[0228] When the wave front reaches a second layer 2012, a third
layer 2013, and a forth layer 2014, the wave front is spread
accordingly over larger and larger spatial extents B, C, and D. As
the distorting affect of the composite material 2005 extends over
the complete wave front, the shape of the wave front is distorted
at all spatial positions within the "surface" of the wave front,
which is illustrated by the large positional fluctuation in the
direction of propagation of the wave front at the forth layer
2014.
[0229] In FIG. 20, the illustration of the deformation of the wave
front is to be understood to be explanatory with regard to an
interaction of the composite material that can vary from layer to
layer, for different types and sizes of particles, etc. While FIG.
20 illustrates the deformation based on a gradient from large to
small particles, also a reversed gradient can interact with an
incoming shock wave layer by layer in a similar manner.
[0230] At the same time, the amplitude of the compression wave is
reduced during propagation of the wave front from layer to layer
indicated through thinner lines for the wave fronts at subsequent
layers. Thus, the form of a compression wave can be perturbed and
stretched. Disruption of the wave form can further assist in
diminishing the destructive potential of a reflected wave. For
example, it causes destructive interference of a reflected and
not-reflected part of the shock wave, thereby reducing, for
example, the combined danger of bomb blasts close to reflecting
surfaces.
[0231] As explained in connection with FIGS. 7 and 8, a shock wave
resulting from an explosive blast can take the form of a sharp
change in gas properties on the order of a few mean free paths, for
example micrometer scale changes in thickness at atmospheric
conditions. While not wishing to be bound by theory, the percentage
of energy lost or dispersed as a wave travels across a composite
medium based on loose particles is not as dependent on the size and
velocities of the particles. The mechanisms can be a function of
the number of particles across the gradient and the amount by which
the particles average size successively decreases across the
gradient. Thus, the normalized kinetic energy of a wave can be
assumed to decay with the number of particles present in the
composite material. Factors intrinsic to a compression wave that
can influence the propagation characteristics of a wave impacting a
composite material can include further, for example, energy flux,
intensity, and pressure associated with the compression.
[0232] The reduction in energy of a compression wave can vary for
any particular embodiment of a composite material. In particular,
the reduction in energy, in accordance with the various
embodiments, can be a function of one or more of the proposed
contributing mechanisms. The level of energy reduction within a
composite material can be analyzed by determining the contributions
from, e.g., the energy dissipated by molecular friction in view of
the potential, kinetic and surface energies within the system, by
rupture of the particles, and redirection of the momentum thereby
reducing. While not wishing to be bound by theory, the level of
energy reduction resulting from the at least partial destruction of
the spatial symmetry can be, for example, a function of the number
of layers of graded particles, the differences in median particle
sizes and masses, and other particulars of the wave form
itself.
[0233] An energy balance analysis as a function of particle to
particle interaction can be calculated by determining: the geometry
of each particle, Poisson's ratio, Young's modulus, and inter
granular surface contact area. For two perfectly spherical
particles having radii R.sub.1 and R.sub.2, and shared contact
surface C.sub.12, the energy between the two spheres can be
expressed as a function of contact area:
Energy c 12 = 8 15 ( ( 1 - .sigma. 1 2 E 1 ) + ( 1 - .sigma. 2 2 E
2 ) ) - 1 R 1 R 2 R 1 + R 2 * C 12 5 2 ##EQU00001##
wherein .sigma. is Poisson's ratio, E is the Young's modulus, and
subscripts 1 and 2 refer to the individual grains. Poisson's ratio,
as used herein, is defined as the ratio of the relative strain
normal to the applied load (transverse strain) divided by the
relative strain in the direction of the applied load (axial
strain). Young's modulus, as used herein, is defined as a measure
of the stiffness of a material, and is also known as the modulus of
elasticity, elastic modulus or tensile modulus.
[0234] Thus, a reduction in energy can be related to real time
effects, such as, for example, a reduction in shock wave amplitude,
shock wave over pressure, area of fragmentation, area of blast
damage, the relative destructive power of the shock wave, and
changes in the mechanical energy generated by the blast. In various
embodiments, order of magnitude reductions in each component can be
expected.
[0235] In other words, when subjected to the impact of a blast, the
impact energy from the blast travels across the composite material
and is increasingly deflected in different directions by the
interaction with the increasing number of contact points. This
multidirectional deflection results in a net reduction of energy as
the directional components increasingly cancel due to opposing
directional components. For a gradient structure, the deflection
due to a size gradient in the average particle sizes of a layer can
also cause breakdown in the translational symmetry of the impact
wave, further resulting in a reduction of energy.
[0236] As exemplified schematically in FIG. 10, as the impact
energy comes in contact with ever changing particle sizes the
impact is differentiated into an ever changing amount of separate
energies each with a distinct vector quantity, characterized by its
magnitude and direction. As the direction of the impact energy
travels across the gradient it is then deflected in different
directions. The deflection results in a net reduction of energy as
the directional components increasingly cancel due to opposing
directional components.
[0237] Further, the impact energy could also dissipate through
inter-granular friction, re-orientation of momentum transfer and
the resulting shear forces within the composite material as the
compression wave traverses the composite material causing
re-orientation of the particles.
[0238] In addition, a blast wave is also disrupted as a result of a
breakdown of translational symmetry, a reduction in the blast wave
energy due to increasing attenuation, or a combination thereof.
[0239] While not wishing to be bound by theory, in one embodiment a
compression wave traveling across a composite material can be
squeezed within the gradient structure due to the reduction or
increase in particle size across the gradient of a composite
material, resulting in at least the partial destruction of the
spatial symmetry of the wave. This can also be expressed as a
breakdown of translational symmetry, wherein a solitary wave loses
its reflection symmetry and is diminished and/or destroyed. In some
embodiments, such a breakdown in translational symmetry can result
in a significant reduction in energy.
[0240] In other embodiments, such a breakdown in translational
symmetry results in a destruction of a wave. In other embodiments,
the translational symmetry relates to the momentum conservation
law, as described by Noether's theorem. As momentum must be
conserved, the speed of the smaller particles will increase, and
thereby disrupt the wave form, and thereby reduce the increase of
the destructive power of the wave e.g. upon reflection.
[0241] While not wishing to be bound by theory, for the gradient
shown in FIG. 9, the leading edge of an impact wave advances first
on progressively smaller particles having less mass, the smaller
particles can, in various embodiments, move at a faster rate than
the larger particles, resulting in a change in the propagation of
the wave. Such a change can be, for example, in the form of a
non-linear increase in wavelength (stretching) of the wave, a
non-linear change in the wave amplitude, and/or a change in the
waveform itself. While not wishing to be bound by theory, a similar
effect on the wave form may be caused when an impact wave advances
on progressively larger particles on the back side of the composite
material 900 or within a densely packed microscale particle
structure.
[0242] As the waveform changes, the wave can, in various
embodiments, experience a decrease in kinetic energy and an
increase in frequency. The increase in wave form frequency, in turn
increases the attenuation of the particles experiencing the
waveform. The maximum attenuation achievable for a particular
system can depend on, for example, the radii and number of
individual particles in the system. Thus, through the selection of
materials, it can be possible to create a specific level or system
of attenuations for a wave.
[0243] Changes, such as increases, in the attenuation of a wave can
assist in the dissipation of a wave's energy. For example, the
frictional dissipation of energy for larger, e.g. macroscale
particles can be on approximately the same scale as collision
energy dissipation. For microscale particles (e.g., nanoscale), the
frictional dissipation can be greater than the collision energy
dissipation.
[0244] In various embodiments, composite materials can provide
engineered material systems, enabling the utilization of
elastoplastic and finite plastic deformation regimes, while
providing control over reflection of the stress wave propagation to
effectively dissipate shock wave progressions.
[0245] The effect of a composite material can also be viewed based
on the propagation of the wave. Waves are transmitted through
gases, plasma, and liquids as longitudinal waves, also called
compression waves. Through solids, however, waves can be
transmitted as both longitudinal and transverse waves. Longitudinal
waves are waves of alternating pressure deviations from the
equilibrium pressure, causing local regions of compression and
rarefaction, while transverse waves in solids, are waves of
alternating shear stress. Shear stress is one way in which our
invention reduces the energy of the wave.
[0246] Matter in the medium experiencing the wave is periodically
displaced by the compression wave. The energy carried by the wave
can convert back and forth between the potential energy of the
extra compression (in case of longitudinal waves) or lateral
displacement strain (in case of transverse waves) of the matter and
the kinetic energy of the oscillations of the medium.
[0247] In regards to kinetic energy, a propagating wave moves the
molecules in the medium which is carrying it, i.e. compression and
rarefaction as the wave travels through the medium. In order for
the compressions and rarefactions to occur, the molecules must move
closer together (compression) and further apart (rarefaction).
Movement implies velocity, so there must be a velocity component
which is associated with the displacement component of the wave.
The resulting velocity is a function of the materials (packing
structure, density, stiffness, mass, inertia). Pressure is a scalar
quantity and has no direction; pressure relates to a point and not
to a particular direction. Velocity on the other hand is a vector
and must have direction; things move from one position to another.
It is the velocity component which gives a wave its direction. The
composite material changes and/or splits the velocity vector as a
function of particles impinging upon one another, thereby reducing
the energy in the system.
[0248] The velocity and pressure components of a wave are related
to each other in terms of the density and springiness of the medium
experiencing the wave. A propagating medium which has a low density
and weak spring would have a higher amplitude in its velocity
component for a given pressure amplitude compared with a medium
which is denser and has stronger springs.
[0249] Mechanical waves originate in the forced motion of a portion
of a deformable medium. Mechanical waves are characterized by the
transport of energy through motions of particles about an
equilibrium position. In case of the composite material, particles
of a first layer subject to an incoming compression wave are
accelerated by the change in pressure and pushed in the direction
of the second layer. As one layer of the composite material after
the other is affected, the wave progresses through the medium. In
this process the resistance offered to deformation by the
consistency of the composite material, as well as the resistance to
motion offered by inertia, must be overcome. As the disturbance
propagates through the composite material, it carries along amounts
of energy in the forms of kinetic and potential energies. The
transmission of energy is affected because motion is passed on from
one particle to the next and not by any sustained bulk motion of
the entire medium.
[0250] Deformability and inertia are essential properties of a
medium for the transmission of mechanical wave. If a medium were
not deformable, any part of the medium would immediately experience
a disturbance in the form of an inertial force, or acceleration,
upon application of a localized excitation.
[0251] When, e.g., the particle diameters progressively shrink in
radius by some factor, the spatial symmetry of the solitary wave is
destroyed. The leading edge of the wave is assumed to travel
progressively faster whereas the trailing part of the wave is
assumed to travel progressively slower. This is due to the lighter
mass of the smaller particles moving faster than their larger
neighbors. Thus, it is assumed that progressively less energy is
carried by the leading edge.
[0252] Thus, the resulting lag and/or compression of a shock wave
20 traveling through a composite material can be used to muffle the
shock wave 20 within the composite material and, when used with,
e.g., elastic materials, can provide a mechanical and/or
electrical/magnetic advantage.
[0253] The induced change in the wave form can be utilized to
provide a smart material that, for example, allows utilizing a
specific change in the wave form to actuate mechanical sensors or
actuators incorporated into the material or those incorporated into
or on the substrate upon which the invention is coated. As an
example, the shock wave can be used to provide an electrical
stimulus to piezoelectric materials, which in turn can actuate a
variety of electrical systems.
[0254] Returning to the structural features of the composite
material, it should be appreciated that the plurality of particles
can provide a level of porosity within the composite material that
depends on the particle size. Thus, the composite material can
includes voids or spaces where particle contact points do not
exist. The porosity can be a continuous pore microstructure within
a given layer of particles or even throughout the entire composite
material itself. Alternatively, the resulting pore microstructure
can also be discontinuous with respect to a given layer of
particles and even discontinuous throughout the entire material
itself.
[0255] The level of porosity (continuous, discontinuous, or a
combination thereof) can affect material properties. When producing
a composite system layer by layer, one can provide a layer specific
porosity. In addition, the size of the pores differs in individual
layers along the particle size gradient. The varying densities
within the composite material can further perturb a compression
wave (amplitude, frequency, spatial form).
[0256] In some embodiments, no binding layer or intermediary
material between the particles is required to hold the composite
material together. In some embodiments, nanoscale and mesoscale
particles but also some macroscale particles can provide surface
interaction that does not require a glue-like binding material and
nevertheless provides the particle sufficient mobility for momentum
transfer. A similar binding between a substrate and a layer
contacting the substrate can be used.
[0257] For example, in some embodiments, functionalized polymer
based microparticles of alternating layers can provide carboxylic
acid and amine groups on their surface. The coupling between the
acid and base functionalities can be used to bind the layers. To
provide, for example, a phenylsulfonic acid functionality on the
surface of a substrate, polar carbon nanoparticle (produced, for
example by Cabot Corp. with the product name Cabot Emperor 2000)
can be incorporated in the substrate or a coating of the substrate.
In particular, carbon nanoparticle based paint materials (e.g., jet
black paint) can be used as the layer upon which the composite
layer structure is built. For example, one would first paint a
substrate with a nanoparticle paint and then apply the first
particle layer.
[0258] As substrate materials, hydrophilic-glass or treated
polycarbonate work well. Both of these materials can be made more
hydrophilic by applying a layer of poly-L-lysine or indoor Rain-X,
a commercial antifogging material. An example of a binding between
a UV treated polycarbonate substrate and the layer contacting the
substrate and between the particles of the layers is described
below in EXAMPLE 4.
[0259] In addition or alternatively, based on an adjusted pH value
during manufacture of the composite material, one can use
electrostatic interactions to bind the layers of
microparticles.
[0260] In some embodiments, some of the microparticles can carry
their own binding coating. For example, microparticles of one of
the layers, can be functionalized with a hydrophobic coating, which
is configured to hold the microparticles to a hydrophobic (polymer)
surface. Thus, such a binding coating can build up an attractive
force to a neighboring layer of polymeric microparticles. Thus,
alternating layers within the gradient layer structure can be
coated and non-coated to form the composite material.
[0261] In some embodiments, charged particles can be based on an
ionomer (charged polymer) as a binder. If microparticles are
positively charged using a functionalized coating, a layer of
microparticles can be followed by a layer of ionomer microparticles
that binds the next layer.
[0262] The above implementations to hold particles together can be
applied to the complete composite material or only to layers of
smaller (nanoscale and/or mesoscale) particles. The implementations
can be applied between layers of microparticles as well as within
one layer between particles. Within a composite material, the
implementations can be used together if feasable or vary within the
composite material.
[0263] In some applications, one will need to complement the
composite material with an intermediary material, which can be
within the composite material, and/or with a binding layer (a top
layer or a layer between layers), such that at least some of the
microparticles (e.g., the larger microparticles of the layer
structure) or all microparticles are held together.
[0264] For example, a polymer filling, e.g. polymerizable monomers,
a resin filling and/or cyclodextrin filling can be used as a
intermediary material. The cyclodextrin can act in a similar manner
as the above discussed ionomer. The cyclodextrin does not need to
fill the pore microstructure completely and uses electrostatics to
bind microparticles.
[0265] In some embodiments, a resin can fill the pore
microstructure and add to some extent to or even increase the
thickness of a layer. Between layers, one can also add a polymer
film that can be made as thin as several nanometers thereby adding
slightly thickness to the layer structure.
[0266] Intermediary materials can be used to fill the accessible
volume. For example, the porosity of the composite material 900 in
FIG. 9 can at least be partially filled with an intermediary
material 950. In general, the intermediary material can span a
portion of at least one particle layer, span an entire particle
layer, or can even span the entire composite material. The
intermediary material can provide some kind of support for the
particles without essentially affecting the mobility of the
particles and the involved momentum transfer between particles.
[0267] The selection of an intermediary material can depend, at
least in part, upon the particular desired effect and the
particular end use application for the composite material. For
example, one can introduce oil into the porosity of the composite
material using capillary effect. Intermediary materials can, for
example, be utilized to alter the energy absorption characteristics
of the composite material. For instance, the intermediary material
can be used to augment the compression behavior of the
material.
[0268] Alternatively, or in addition, a fire retardant can be
incorporated into the system as an intermediary material. Moreover,
examples for an intermediary material can include materials that
when combined via pressure and temperature, interact with the
surrounding material to change the characteristics of the resulting
material to produce foam, aerogel, solgel etc.
[0269] Furthermore, the intermediary material can change the
density of a given layer to further disrupt the wave form of the
compression wave. The intermediary material 950 can further change
the stiffness of the composite material 900, thereby allowing the
composite material to be free standing, for example. The
intermediary material can further be used to impart cosmetic or
aromatic value to the composite material.
[0270] In any of the composite materials illustrated in the
drawings, intermediary material can in principle be used or it can
be applied either in whole or in part throughout the structure.
[0271] In addition to the energy absorption properties provided by
the gradient layer structure and the densely packed particle
structure, the composite material can include core-shell particles
1100 as shown in FIG. 11. The core-shell particles can themselves
modify the energy absorption and in addition can provide in some
embodiments a material release function to the composite material.
The core-shell particles 1100 includes a core-material 1110 (e.g.,
solid, liquid, gaseous, gel-type material) within a shell 1120. The
core material can fill the encapsulated material completely or
partly, e.g., the core is filled with different aggregate states.
Further, combinations of materials can be encapsulated. Examples
for a core-shell particle 1100 include filled microspheres (or
spheres) and other encapsulating particles that encapsulate one or
more core materials 1110. In some core-shell particles the core can
be hollow (e.g., filled with a gas).
[0272] The thickness of the shell 1120 can be, for example, between
30% and 1% of the diameter of the core-shell particle 1100. The
score-shell particle can be a microscale particle. In some
embodiments using a large amount of a specific core-material, the
core-shell particles can have a diameter of several
millimeters.
[0273] The shell material of the shell 1120 can be pliable such
that the shell 1120 can deform, e.g., upon impact of a compression
wave of a bomb blast. The shell material of the shell 1120 can in
addition or alternatively be pliable such that the shell 1120 can
deform when subjected to, for example, over pressure. The
deformation and pliability can contribute to the energy absorption
process.
[0274] The core-shell particles (as well as the particles in
general) can be spherically or asymmetrically shaped. The shell
1120 can be a continuous wall surrounding the core or can be
designed to have droplets of the core material embedded through the
microcapsule. In some embodiments, the shell can be porous.
[0275] Upon impact of a compression wave, the particle shells 1120
within an impacted layer can deform such that a portion of the
energy associated with compression wave is therefore absorbed by
the core-shell particle. As the shell 1120 deforms, it can also
apply pressure to particles adjacent to it, thus transferring a
portion of the impact energy to the energy required for subsequent
deformation and angular pressure on neighboring particles.
[0276] Moreover, to provide specific features in a, pre-blast
environment, for example, the core material can be configured to
have various features. For example, it may operate as RF shielding
to impede remote detonation of bombs.
[0277] Additionally, or alternatively, the core material 1110 can,
for example, include an agent material (e.g., a secondary blast
agent), the presence of which can be utilized to interact with
secondary blast effects in a post blast environment in a
predetermined manner. For example, in one embodiment, the
core-shell particles 1100 can encapsulate one or more agent
materials capable of mitigating and/or remediating secondary blast
effects, such as flash, fire, chemical agent release, biological
agent release, radiation release, and shock wave caused damages. To
that end, agent materials can include without limitation, fire
retardants, flash suppressants, medicinal treatments, and the
like.
[0278] The core-shell particle 1100 can also encapsulate one or
more agent materials that when combined through actuation or
actuation and rupture, can interact with each other or with the
blast environment to produce a desired effect. For example, in one
embodiment it is contemplated that separate agent materials can be
encapsulated such that when combined through rupture of several
core-shell particles 1100 the materials react to generate fast
setting structural foam. Such foam can, for example, assist in
mitigating and/or remediating oil loss from ruptured pipelines as
explained in connection with FIG. 18 below.
[0279] In use, the shell 1120 of the core-shell particle 1100 can
deform under the impact pressure from a shock wave to a deformation
where shell rupture occurs, thus releasing the core material 1110
as an agent material, e.g., a secondary blast agent, which is
thereby directly released into the blast zone. The released agent
materials can then directly interact with the environment to
mitigate and/or remediate, e.g., one or more secondary blast
effects.
[0280] Moreover, it is contemplated that by exposing an agent
material to a combination of relatively large pressure and heat
changes, the released agent material can, for example, be consumed
in or can otherwise participate in a reaction that produces further
reaction products that can also be beneficial to remediation and/or
mitigation of blast effects.
[0281] As shown in FIG. 12, core-shell particles can form a
composite material 1200 that can be applied as a coating or as a
film to a substrate 1210, for example, before or after applying a
gradient layer structure. The composite material 1200 includes
three mono-dispersed layers of core-shell particles 1220, 1230, and
1240. The core material of the layers 1220 and 1240 is indicated to
be the same (vertical hatching) and to be different from the center
layer 1230 (diagonal hatching). Under certain conditions, e.g.,
under high pressure caused by an explosion, the shells of the
core-shell particles rupture and release the core material. The
core material can provide mitigation for itself and/or in
combination and/or after reaction with each other. The
functionality of the composite material 1200 can thereby be adapted
to the specific application.
[0282] Thus, as shells rupture in successive layers, agent
materials contained in different core-shell particles can be
sequentially introduced into the blast zone allowing more complex
systems to be introduced and allowing sequential reactions to occur
in a predefined manner. This staggering of additional agent
materials (secondary agent materials, tertiary agent materials,
quatemary agent materials, etc.) in a pre-designed manner can
further allow sequential reactions whose sum reaction is greater
than their individual contributions.
[0283] The composite material 1300 of FIG. 13 includes a single
mono-dispersed core-shell particle layer 1310, a gradient layer
structure 1320, a densely packed particle structure 1325, and a
substrate 1330.
[0284] Mono-dispersed layer 1310 made of core-shell particles is
provided in front of gradient layer structure 1320. Moreover, layer
1335 of the gradient layer structure 1320 includes core-shell
particles and layer 1345 of the densely packed particle structure
1325 includes also core-shell particles. Thus, the advantages of
the composite material can be combined with the advantages of the
core-shell particles. This allows further adapting threshold
conditions within the gradient layer structure for the release of
the core-material.
[0285] Similarly, core-shell particles can be included in
concentric gradient layer structures. In FIG. 14, a composite
material 1400 includes as a center particle a core-shell particle
1410. A layer 1420 having a thickness of multiple particle
diameters is formed around the core-shell particle 1410 as a
densely packed particle structure. Then, three concentric layers
1430, 1440, 1450 consisting of mono-dispersed particles of
increasing size are applied. An intermediary material 1460 provides
structural cohesion of the particles.
[0286] FIG. 55 shows a cross-section of a densely packed particle
structure that includes (from left to right) a core-shell particle
size small, a solid particle size small, a core-shell particle size
large, a solid particle size small, a solid particle size large.
Due to the difference in size, the small particles can fill spaces
between the large particles thereby interlocking the different
particle layers.
[0287] Plotting the size of the particles over the layers provides
access to the type of structures included in a composite material.
For some of the presented examples, the particle size dependence
was illustrated in FIGS. 43 to 45. However, the composite material
is not restricted to two or three structural units, where a
structural unit is a gradient structure or a densely packed
structure. (It is noted that also a gradient structure includes
densely packed particles but with the additional requirement of a
particle size gradient). One can repeat structural units, alternate
structural units, repeat combination of structural units, or
combine different combinations of structural units.
[0288] Additional examples of combinations of structural units are
shown in FIGS. 46-48. In the configuration shown in FIG. 46, a
gradient structure is provided on each side of a densely packed
particle structure, such that on both sides small particles form
the outer surface, i.e., the gradients have opposite direction.
[0289] In the configuration shown in FIG. 47, two outer gradient
structures form gradients in different ranges of particle sizes
with large particles form the outer surfaces. An inner densely
packed particle structure includes also larger particles.
[0290] In the configuration shown in FIG. 48, densely packed
particle structures 4810 and 4820 of different particle sizes and
thicknesses form a sandwich structure with an inner one-directional
gradient structure.
[0291] As discussed herein, the particles of the gradient
structures and densely packed particle structures can be solid
particles or core-shell particles. FIGS. 49-54 illustrate various
examples of distributing and mixing these particles with in a
composite material. A similar freedom exists for different types of
particles, such as shapes, materials etc.
[0292] In FIG. 49, two densely packed particle structures of
different size are in contact with each other, one having
exclusively solid particles and the other exclusively core-shell
particles. Even though three particles are indicated, each densely
packed particle structure may have 10, 20, 30, . . . 50, 60, . . .
100 layers or a thickness of 10, 20, 30, . . . 50, 60, . . . 100
(non-layered particles). In addition, the layers may be looser so
that there is some overlap between neighboring layers as described
above. For small numbers of particles for each size, one may repeat
the sequence of the two sizes to form a densely packed particle
structure.
[0293] While in FIG. 49 the particles of each type were essentially
of the same size, FIG. 50 shows an embodiment in which each type of
particle covers a range of sizes that are randomly arranged within
each densely packed particle structure. Even though the first and
the last particle of densely packed particle structure may not have
the same size, this difference is not considered to be a gradient
in view of the fluctuation of the particle size. While the solid
particles of the densely packed particle structure having a smaller
size has the same size in the first and fifth layer, the core-shell
particles of the first and fifth layer decrease slightly in size.
Due to the fluctuation in particle size of the core-shell
particles, the second layer from the right has even a smaller size
than the fifth layer.
[0294] FIG. 51 illustrates that particles within a densely packed
particle structure can include solid and core-shell particles
either within a range of particle sizes (left side) or with the
same size (right side).
[0295] While FIGS. 49 to 51 referred to two densely packed particle
structures only, FIGS. 52-54 illustrate similar particle size
distributions for gradient structures and densely packed particle
structure (FIG. 52), densely packed particle structure and gradient
structures (FIG. 53), and for two gradient structures (FIG.
54).
[0296] Based on the above described composite materials, exemplary
applications are described in connection with FIGS. 15-19, 21-24,
and 42.
[0297] FIGS. 15 and 24 illustrate the application of the composite
material in the context of waste receptacles. In FIG. 15, the
composite material is attached to a support structure of a
container 1500, forming for example, the structural basis for a
waste receptacle. The inner surface of the container 1500 is coated
with a composite material 1510 including a gradient layer structure
and a densely packed particle structure that forms the inner
surface of the container 1500. The composite material is
representative for various configurations of the composite
material, and the combinations of gradient layer structures,
densely packed particle structure, and core-shell particle layers
as discussed within this application, for example, in connection
with FIGS. 3-6, 9, 11-14, 22, and 24, whereby the directions of the
gradients illustrated in those figures is only exemplary and can be
for example, reversed or vary in direction and strength.
[0298] Thus, any explosion initiated within the container 1500 and
generating a shock wave is reduced in its destructive power because
the shock wave looses intensity when traveling through the gradient
layer structure and when reflecting from the coated walls of the
container 1500. Additionally or alternatively, the outer surface of
the container can be coated with a gradient layer structure.
[0299] Moreover, instead of being applied as a coating, the
composite material 1510 can be attached as a film or panel. In some
configurations, the support structure can be only a frame and the
composite material forms, for example, transparent walls to that
frame.
[0300] Alternatively, or in addition, the waste receptacle itself
may consist entirely of the gradient layer structure as will be
discussed below in connection with FIG. 24.
[0301] Moreover, the composite material can be transparent, opaque,
or non-transparent and it can be manufactured, for example, as a
film or as a bag, e.g., a waste receptacle liner. Moreover, it can
be made as individual bags or in rolls, which separate at
serrations. The film can be applied onto a substrate of any shape.
The composite material can mitigate and/or remediate by absorption
and dissipation in a predetermined manner, for example, effects of
a bomb blast, which originates on either side of the composite
material. In addition, the composite material can use the shock
wave to mitigate and/or remediate the bomb blast by rupturing
and/or vaporizing core-shell materials, such as microcapsules,
which populate the gradient layers as one of the gradient layers or
as a layer attached to the gradient layer structure. The core-shell
material can be hollow or filled with material (core-material),
concentric and/or non-concentric as discussed within this
application.
[0302] Materials suitable as core material for core-shell particles
of a core-shell particle layer, e.g., next to a gradient layer
structure 1510 or forming a layer within the gradient layer
structure 1510 or the densely packed particle structure, include
flame retardants and suppressants, foam-generating materials and
dispersants, materials which suppress and/or deform acoustic waves,
materials which suppress smoke and dust, for example. The core
material can further contain materials associated with medical
treatment, for, for example, burns, infection, inflammation, pain,
antibiotics, and materials used for triage medical treatment,
materials which impede RF transmission, and/or electrical impulses,
in order to reduce the risk to first responders from secondary
devices placed and planned to be activated by remote signal, and
material which impede the dispersal of biological and radioactive
agents.
[0303] The composite material can further contain a sensor material
that changes color when activated by a specific chemical signature
of matter in its environment, e.g., carried by solid particles,
gases, and/or liquids. The sensor material can be contained in the
particles of the composite material, e.g., in filled or hollow
microspheres and/or core-shell particles of the gradient layer
structure 1510 and/or a core-shell particle layer (e.g., core-shell
particle layer 2220 in FIG. 22). The sensor material can
additionally, or alternatively be contained in a film or coating
material, e.g., forming an outside surface of the composite
material. Moreover, in addition, or alternatively, the sensor
material can be contained in a binding layer (e.g., binding layer
2440 in FIG. 24) and/or in an intermediary material of the
composite material (e.g., intermediary material 950 of in FIG.
9).
[0304] For example, explosives that release a (gaseous) material
with a specific chemical signature can yield a concentration above
a predetermined concentration in, e.g., a closed or partly closed
waste receptacle. Then, the sensor material acts as a (chemically
triggered) sensor and identifies the presence of the explosive in
the waste receptacle by changing its color. The composite material
with the sensor material can be part of a waste receptacle or of a
waste receptacle liner or any structure subject to be used for
hiding an explosive.
[0305] Example sensor materials for detecting explosives such as
C-3, SemtexH, and TNT include a mixture comprised of zinc, glacial
acetic acid and the NitriVer 3 Reagent supplied, e.g., by the Hach
Co. (Cat #1407899). These materials can be combined in solution
with water and can then be applied as a sensing film that is dried
onto the gradient layer structure, onto the core-shell particle
layer, and/or in between particle layers. In addition, or
alternatively, these materials can be presented separately as,
e.g., microscale particles (such as nanoscale particles) or
coatings on microscale particles (such as nanoscale particles) in
the gradient layers. Example particles that can be coated include,
for example, zinc particles and polymer particles with acid groups.
Moreover, the materials can be provided as a shell material of a
core-shell particle. The reaction and detecting of, for example,
TNT or RDX as described above can be adapted from the method as
described in EPA METHOD 8510 "COLORIMETRIC SCREENING PROCEDURE FOR
RDX AND HMX IN SOIL" Revision 0, U.S. Environmental Protection
Agency, February 2007 (http://www.epa.gov/SW-846/pdfs/8510.pdf),
the contents of which are hereby incorporated by reference in their
entirety.
[0306] The inner layers of the composite material 1510 can provide
gradient layer structures and densely packed particle structure
with particles in size and sequence such that a distortion of the
compression wave is achieved. Moreover, the reflected wave can be
distorted and/or diminished such that, for example, the primary and
secondary effects of the combined compression wave (based on the
reflected wave and the initial compression wave of the bomb blast)
are at least to some degree mitigated and/or remediated.
[0307] An inner layer of the composite material, with which a
person usually cannot get in contact, can also include particles
(microparticles, core-shell particles etc.) that contain a
rodenticide for, e.g., rat control. In case of a bomb blast, the
rodenticide vaporizes and/or incinerates and would not harm the
environment. The layers, which contain the rodenticide, can be
changed by generation of manufacture to account for the evolution
of immunities in the area's rodent population.
[0308] As noted above, the composite material 1500 and the
composite material 2400 can alternatively, or in combination, also
be implemented in a liner that is used with a waste receptacle or
used as a separate bag for waste material. In some embodiments that
apply the composite structure to waste receptacles, the composite
material as part of the liner or the receptacle is transparent.
[0309] When, for example, a bomb detonates within the container
(waste receptacle), by the use of a timing device, (because RF
shielding makes detonation by a radio signal sent to a cell phone
or other radio receiver at the bomb ineffective), layers of the
composite material closest to the detonation absorb the blast
energy and cause rupture of the core shell particles within the
composite material, which release their contents. As the shock wave
moves through the composite material to the inner layer particles,
deformation of the shock wave increases.
[0310] Further, as the shock wave propagates, the core-shell
particles rupture in a predetermined sequence and can introduce
materials into the blast environment that act, for example, as a
flame retardant and dispersant and suppressant, sound suppressant,
smoke and dust suppressant. The core-shell particles can further
introduce into the environment materials that are used to treat
burns and other wounds, impede the dispersal of biological and
radioactive agents, as well as RF shielding materials and materials
which impede electrical impulse, designed to reduce the risk to
first responders from a second detonation caused by other devices
placed and planned to be triggered by a remote signal after their
arrival to aid blast victims.
[0311] In other embodiments, fibers and textiles, in general,
helmets, helmet liners or helmet liner pads, and any existing
structure or item can be coated or provided with a film as
illustrated, for example, in FIGS. 16, 17 and 22. Fibers can be
woven into cloth and thereby shield the wearer at least partly from
an impacting compression wave. The coated fiber 1600 of FIG. 16
includes a core fiber 1610 that has been coated with a sequence of
mono-dispersed layers 1620 of particles with increasing size. The
particles are confined through an intermediary material 1630.
Alternatively, one could form a similar structure without the core
fiber 1610 or remove the core fiber 1610 after the gradient layer
structure has been formed. As indicated above, densely packed
particle structures can be formed by one or more of the gradient
layers or by applying densely packed particle structures next to
the gradient structure.
[0312] In FIG. 17, an alternative coated fiber 1700 includes a core
fiber 1710 that has been coated with the concentric composite
material 1400 of FIG. 14. Different core-materials 1720 and 1730
for the composite material 1400 are indicated. A cloth including
the coated fiber 1700 provides mitigation and/or remediation of an
incident compression wave and additionally can provide agent
materials, such as medicine or flame suppressants and retardants.
Thus, agent materials can be introduced where they are needed the
most upon impact of a bomb blast. Similarly, a helmet, helmet liner
or helmet liner pads can be coated with composite materials of that
kind as discussed in connection with FIG. 21. Alternatively, the
helmet liner and helmet liner pads can be made with composite
materials of the kind discussed in connection with FIG. 21. As
indicated above, densely packed particle structures can be formed
by one or more of the gradient layers or by applying densely packed
particle structures next to the gradient structure.
[0313] Destructive compression waves can also be generated under
different conditions. For example, the opening and closing of
valves in pipeline systems can generate compression waves, even
shock waves that propagate along the pipes and can case damage,
including the rupture of the walls of the pipes. FIG. 18 shows
schematically a pipe 1800 with a valve 1830. To reduce the risk of
compression wave induced damage, the inside of the pipe 1800 can be
coated with a composite material 1810 including a gradient layer
structure, a densely packed particle structure, and an intermediary
material 1815. The gradient can be formed perpendicular and/or
parallel to the walls of the pipe 1800. A compression wave 1820
generated when operating the valve 1830 will then decrease in
amplitude when impacting onto or traveling along the walls of the
pipe 1800. Additionally, or alternatively core-shell particles can
be included in the composite material 1810, thereby providing a
core material for, e.g., mitigating the damage of leaking oil or
sealing hair fractures of the pipe 1800. In addition, or
alternatively, the outside can be coated similarly.
[0314] Thus, applications of the composite material can include the
mitigation and/or remediation of a compression wave, caused by,
e.g., a bomb blast or the opening or closing of values, traveling
along pipelines and other conduits used for transport of liquids
and gases, to include fossil fuels, flammable liquids, and waste
materials and to mitigate and/or remediate fire, leakage, release
of gases and/or other effects. The composite material can be
manufactured into a casing, outer and/or inner coating, cladding,
film or liner. The composite material can further be designed to
alleviate stress and fatigue caused by experiencing extreme changes
in temperature.
[0315] In the following, the case of fossil fuel pipelines is
discussed as a specific example in greater detail. Especially in
areas with risk of asymmetric warfare, pipelines can be provided
with layers of the composite material on the inside and on the
outside. Then, the composite material can mitigate and/or remediate
the effects of a bomb blast by absorption and dissipation in a
predetermined manner, which can originate on either side of the
material. In addition, one can use the wave to mitigate and/or
remediate effects of the bomb blast and the leaking, eventually
burning oil, by rupturing and/or vaporizing, e.g., core-shell
particles, which populate specific layers within or next to the
gradient layer structure of the composite material. Particles of
the outside gradient layers, for example, can contain flame
retardants and flame suppressants, foams and dispersants, smoke
suppressants. Some core-shell particles can further include
materials associated with the treatment of burns, infection,
inflammation, pain, antibiotics, and materials used for triage
medical treatment. Other core-shell particles can contain a
material that blocks RF transmission, and impedes the dispersal of
biological and/or radioactive agents.
[0316] The interior layers of the composite material are configured
in a gradient layer structure to cause maximum disruption of
compression wave and diminishing of the reflected wave. Some
particles within or bordering to the gradient layer structure can
be core-shell particles containing surfactants, which can break
down and aid in the dispersal of fossil fuels in order to mitigate
and/or remediate its effect on the environment. Inside and outside
layers can contain core-shell particles with a core material that
alleviates stress and fatigue caused by experiencing extreme
changes in temperature.
[0317] When, for example, a bomb detonates next to the pipeline,
the outer layers of the composite material closest to the
detonation absorb the blast energy and cause thereby the rupture of
the hollow particles and core-shell particles, which release their
contents. As the shock wave moves through the composite material,
deformation of the blast wave increases. Further, as the wave
reaches those core-shell particle layers one after the other, the
rupture of core-shell particles can occur in a predetermined
sequence to provide a flame retardant and suppressant, generate
non-flammable foam, and/or other coagulants designed to contain the
flow of materials thereby preparing the area for decontamination
and collection of the material released by the effect of the blast
into the environment. Contemporaneously, the composite material can
introduce into the blast's target environment the materials that
treat burns and other wounds or impede the dispersal of biological
and radioactive agents. It can further introduce into that
environment RF shielding materials.
[0318] In FIG. 19, a hand held device 1900 is coated with a
composite material 1910 to increase the resistance against impacts
by affecting the propagation of a shock wave caused by, e.g.,
falling onto the ground. Alternative examples, for devices that can
profit from shock absorption as explained, for example, in
connection with FIG. 20 include laptops, cell phones, audio
devices, and e-books.
[0319] FIG. 21 illustrates the application of the composite
material in the context of a shielding device, specifically, a
helmet 2100. The helmet includes a helmet structure 2110 to which
helmet liner pads 2120 are attached. It is common to wear a helmet
just with those helmet liner pads in certain environments. In
addition, one can wear the helmet 2100 with a helmet liner 2130
that can give additional shelter for a specific environment
(temperature, sun light, wind, sand, etc.). In some configurations,
one uses the helmet liner 2130, for example, a cold weather helmet
liner, with the helmet liner pads 2120. A compression wave caused
by a detonating bomb or hitting a hard surface, e.g. pavement, can
be mitigated and/or remediated based on the composite material
including a gradient layer structure, a densely packed particle
structure, and/or a core-shell material, which mitigate and/or
remediate by absorption, dissipation, and providing core materials
in a predetermined manner the effects of the compression wave
striking the helmet 2100. The composite material can be
incorporated into the helmet liner pads 2120 and/or the helmet
liner 2130 and/or the helmet structure 2110.
[0320] The composite material, in addition to mitigating the
effects of the compression wave, can signal concussive injury with
or without penetration of the helmet 2100. It can provide immediate
treatment of wounds with antibiotics, anti-inflammatories, pain
medicine and blood coagulants, for example, for helmet penetrating
and non-penetrating events before triage medical treatment. The
composite material can therefore maximize the comfort of the helmet
wearer while providing various safety features.
[0321] The composite material can be either applied directly onto
the helmet as an inside and/or outside coating 2140. The composite
material can further be incorporated in the helmet liner pads 2120
and/or the helmet liner 2130. Different composite material can also
be provided in a series of pad elements 2121, 2122, 2123 thereby
providing specific features at different locations. In some
applications, the exterior layers of the pads closest to the wearer
are designed to wick away moisture.
[0322] The material of the composite material can be
self-extinguishing when exposed to combustion. The material can be
a material that vaporizes and/or otherwise become a material, which
will not drip, thereby protecting the scalp and skin of the wearer
of the helmet 2100 from burns and aggravation of head and/or neck
injury.
[0323] An exemplary structure for the series of pad elements 2121,
2122, 2123 is shown in FIG. 22. The microcapsules in the composite
material rupture when impacted at different levels of force. The
composite material that is closest to the scalp and skin and
closest to the helmet structure is based on a gradient layer
structure 2210, 2230. In FIG. 22, only one gradient layer structure
and one densely packed particle structures next to the gradient
structure is shown within the pad elements 2210 and 2230 but many
more gradient layer structures with gradients of various directions
and amplitudes and densely packed particle structures can be used.
In general, the gradient layer structures 2210, 2230 each can be
sequenced to increase the absorption of the compression wave.
[0324] The gradient layer structures of the pad elements 2210 and
2230 closest to the scalp and skin can further include core-shell
particles 2240, 2250 with core materials such as flame retardants
and suppressants, materials that wick away moisture, antibiotics,
anti-inflammatories, pain medicine and blood coagulants.
[0325] The composite material of an intermediary pad element 2220
can include a densely packed particle structure of core-shell
particles that provide after rupture an inelastic non-toxic
inflammable foam. The foam can expand into a space 2150 between the
head and the helmet structure 2110 thereby stabilizing the helmet
head system and any head injuries. In addition, or alternatively,
the foam can be contained within the helmet liner pad or pads
and/or the helmet liner thereby increasing their size and
tightening the helmet to the head. Thus, the inelastic foam
mitigates and/or remediates by absorption and by keeping the helmet
properly seated to protect the skull from further impacts and
exposure to, e.g., the heat from combustion.
[0326] The helmet liner and/or the helmet liner pads can be made
completely of pure composite material pad elements as shown in FIG.
22. Alternatively, a pad can include a cushioning material around
which (or in between layers of the cushioning material) the
composite material is wrapped in a textile like structure. For
example, the intermediary pad element 2220 can be replaced with a
cushioning material.
[0327] In some embodiments of the pads or the helmet liner, the
composite material can include core-shell materials that contain a
non-toxic, and washable, dye. Assuming that there is no penetration
of the helmet 2100, when impacted by a compression wave, the
gradient layer structures closest to the helmet mitigate and/or
remediate the force of the compression wave. However, if the force
of the impact is within a specified range, the composite material
acts as a (physically triggered) sensor when the color filled
core-shell particles rupture and mark the areas of impact or the
occurrence of a compression wave.
[0328] When the helmet is removed, it is possible to determine that
the wearer has sustained a possible concussive injury even though
there is no penetration of the helmet. If the dye is triggered,
after the helmet is examined and/or the wearer. In some
applications, the dye can then be removed when washed.
[0329] The gradient layer structures continue to interact with
following compression waves.
[0330] The layers closest to the skull, in addition to absorbing
the impact, can also direct the force away from most sensitive
areas of the skull thereby using the compression wave against
itself to maximize the distortion of the compression wave.
[0331] Even in the case of a penetration of the helmet 2100, the
core-shell particles closest to the skull, which can contain
antibiotics and blood coagulants will rupture within the region of
penetration, and thereby delivering their content into any wounds
created and mitigating and/or remediating by triage treatment
designed to stabilize medical conditions, prevent infection and to
aid in cauterizing the wound.
[0332] The above discussed features can similarly be implemented
in, e.g., different layers of a "cold weather" liner. Thus, the
helmet liner 2130 itself can contain a composite material with
core-shell particles providing various materials, when ruptured. In
addition to absorb the blast wave, the generated foam can also
protect against and treat neck wounds and provide acoustic
protection as the foam can cover the neck and the ears of the
wearer.
[0333] Due to the modular concept, the helmet liner pads 2120
and/or the helmet liner 2130 can be replaced after the mitigation
and remediation of an impact or if some core-shell particles have
ruptured or exchange is appropriate.
[0334] The above discussed features can similarly be implemented
within the inside and/or outside coating 2140, which can be
reapplied if necessary.
[0335] Example helmets include combat helmets and sport helmets,
such as bike helmets, riding helmets, and motor cycle helmets.
[0336] The composite material can further be applied in form of a
panel, e.g., a piece of molded composite material which you can
attach to either a specific part, the door of a vehicle, for
example, or which you can attach to a plate, like those suspended
from the side of assault vehicles. The panel can further be easily
transported and mounted to building or any object (large or small)
that can benefit from shielding against compression waves.
[0337] In the following, the composite material is discussed in the
context of shielding a transportation device, for military and/or
civilian use. FIG. 23 shows schematically a transportation device
2300 such as vehicles, ships, boats, and aircraft, (airplanes,
helicopters, space ships, etc.) or a part thereof. The
transportation device can be manned or unmanned. It can transport
people, surveillance devices, measurement devices, ordinance, or
goods. Specific examples include tanks and Humvees (e.g., exterior
shielding), airplanes, and helicopters (e.g., body, cockpit glass,
engine, ordinance, and rotor blade shielding), unmanned drones used
for surveillance and/or as a weapons platform (e.g., body, engine,
optics, exterior and ordinance shielding), ships and submarines
(e.g., hull and wall shielding).
[0338] The composite material can be applied to a surface of the
transportation device 2300 as a coating 2310. Alternatively or
additionally, the composite material can be attached to the surface
as a removable unit 2320, e.g., as a film or panel that fits to and
is shaped according to the shielded surface. Alternatively the
composite material can be used as filling material for cavities of
outer wall structures of the transportation device 2300, e.g., to
fill the outer walls of ships or the doors of cars with, e.g.,
granular composite material based on concentric gradient layer
structures.
[0339] The composite material mitigates and/or remediates the
effects of a blast through its structure and by using that force as
an activator to rupture and/or vaporize core-shell materials
containing core materials, which are, e.g., flame retardants and
suppressants, foam generators and dispersants, smoke suppressants,
materials which can impede RF transmission and electrical impulses,
materials associated with the treatment of burns, and other wounds,
infection, inflammation, pain, antibiotics, and materials used for
triage medical treatment, and materials which act as a shield
against biological and radioactive agents. The composite material
can be transparent when applied, e.g., to glass, polycarbonate
resin, or other materials used for viewing without essentially
distorting visibility and degrading over period of use and exposure
to extreme changes in temperature.
[0340] For example, for a vehicle, the composite material can be
applied as a film attached to the surface of the vehicle, or can
form completely molded panels attached to the sides, bottom and
top. The composite material can be re-applied in field conditions
after the composite material is triggered by a bomb blast. When
used as a panel, as a coating, or as a film, the composite material
can be light in weight. The outer layer of such a panel and/or film
closest to the vehicle can contain a resin to bind it to the
vehicle.
[0341] When, for example, a bomb detonates in the vicinity of the
vehicle (representative for any transportation device), the outer
layers of the composite material closest to the blast absorbs the
blast energy causing the rupture of core-shell particles, the
latter releasing the flame retardants, dispersants and
suppressants, the smoke suppressants, as well as injecting into the
targeted environment materials used to treat burns, and other
wounds, infection, inflammation, pain, antibiotics, and materials
used for triage medical treatment. Additionally, the composite
material can introduce into that environment RF shielding materials
or other materials to impede the transmission of electric impulses
and thereby to reduce the risk to personnel already on site and to
first responders from another bomb triggered by a remote signal
following the initial blast. Materials to impede biological agents
and radioactivity can also be introduced into the target area.
[0342] As the shock wave moves from the outer layer through the
composite material, to the inner layer particles, deformation of
the blast wave increases. Contemporaneously, the shock wave
activates core-shell materials within the composite material, while
at the same time the inner layers direct the shock wave in a
predetermined manner to those areas where the vehicle is best
protected against blast waves.
[0343] In FIG. 24, a waste receptacle 2400 consists entirely of a
composite material that includes gradient layer structures 2410 and
2415 and core-shell particles 2420 and 2430. The core-shell
particles can be part of the gradient layer structure as
illustrated for the core-shell particles 2420 in the gradient layer
structure 2415. The core-shell particles can further form a layer
themselves as illustrated for the core-shell particles 2430. The
outer particles of the composite material can be confined by a
binding layer 2440. The binding layer can include, for example, a
sensor material that changes color in response to a chemical
signature in its environment. The binding layer 2440 can
alternatively or additionally be provided between layers of the
composite material, e.g., between the core-shell particle layer
2430 and the gradient layer structure 2420. As discussed above one
or more layers of the gradient layer structure can include
multi-particle layers and thereby form densely packed particle
structures. Additionally or alternatively, one or more densely
packed particle structures can be included next to the gradient
structure 2420.
[0344] Materials suitable as core material of the core-shell
particles 2420, 2430, include flame retardants and suppressants,
foam-generating materials and dispersants, materials which suppress
and/or deform acoustic sound waves, materials which suppress smoke
and dust, for example. The core material can further contain
materials associated with the treatment of burns, and other wounds,
infection, inflammation, pain, antibiotics, and materials used for
triage medical treatment, Moreover, materials can include RF
transmission blocking materials that impede electrical impulses,
and/or materials, which impede the dispersal of biological and
radioactive agents in order to reduce the risk to first responders
from secondary devices placed and planned to be activated by remote
signal. The core material can fill the shell completely or partly,
and can be provided itself as core-shell particle(s), such as
microcapsules.
[0345] One can manufacture the complex structure of the composite
material for the waste receptacle layer by layer or attach
pre-manufactured, e.g., layer sequences. The composite material can
moreover be used in the form of a clear or opaque material.
[0346] As a shell material and/or a core material of the core-shall
particle layers 2420 and 2430, the composite material can include a
material that changes color (for example, in response to gaseous
chemical signatures of explosives as discussed above in connection
with FIG. 15), fire suppressant, and/or a rodenticide. For example,
those materials can be present in the surface layer, or any inner
layer of the composite material.
[0347] Additional applications can involve the suppression of
compression waves to make wall structures or windows safer. As
shown in FIG. 42, a safety glass 4200 includes two side windows
4210. A composite material 4220 is positioned between the two side
windows 4210. To be transparent, the particles of the composite
material can be made of, for example, silica or glass. Also small
size polymer nanoparticles of the order of 100 nm (e.g.,
polystyrene particles) can also be essentially transparent. Side
windows 4210 are at least partly transparent and can be made, for
example, of polymers (e.g., polycarbonate). Composite material 4220
can be attached to at least one of the side windows 4210. In safety
applications, the composite material can be applied, for example,
as a coating or film. Alternatively, composite material 4220 can
be, for example, be positioned as a self supporting foil between
the two wide windows 4210. Also composite material 4220 is at least
partly transparent.
[0348] The structure as described in FIG. 24 can similarly also be
the basis for a waste receptacle liner or any of the herein
described embodiments. In general, any structure and use of
material in any of the configuration described herein with
reference to a specific application of the composite material can
be applied in a similar way to another application or configuration
of the composite material. For simplification, the various
configurations and applications of the composite material were
discussed based on drawings showing primarily layers that consist
of essentially a single particle in direction of the thickness of
the layer. However, each of the illustrated layers can in principal
be a mono-dispersed layer or multi-particle layer and thereby be
representative for a densely packed particle structure. In the
following FIGS. 25 to 27, composite materials with multi-particle
layers (two layers again being representative for two and more
layers) are discussed in more detail. These or similar composite
materials can be used in embodiments as described for example, in
connection with FIGS. 1 to 6, 9, 13 to 24.
[0349] For example, while FIGS. 1 and 2 show generic embodiments of
composite materials 100 and 200, respectively, FIG. 25 shows an
embodiment of a composite material 2500 with a particle size
gradient formed by mono-dispersed and multi-particle layers.
Specifically beginning at the small-particle side, two
mono-dispersed layers 2510 and 2520 are densely packed. A first
multi-particle layer 2530 comprises two densely packed sub-layers
2530A, 2530B and a loosely packed sub-layer 2530C. Sub-layer 2530C
interleaves with loosely packed mono-dispersed layer 2540 that on
the other side interleaves with a first of three loosely packed
sub-layers 2550A to 2550C of multi-particle layer 2550. The largest
particles form a multi-particle layer 2560 of two densely packed
sub-layers 2560A and 2560B, being a two layer densely packed
particle structure.
[0350] In densely packed mono-dispersed layers and densely packed
mono-dispersed sub-layers (e.g., mono-dispersed layer 2510 and
sub-layer 2560B), particles are in contact with the neighboring
particles within the layer and sub-layer, respectively. In
contrast, particles of loosely packed mono-dispersed layers or
sub-layers are mostly not in contact with the neighboring particles
within the layer and sub-layer but are in contact with particles of
neighboring layers/sub-layers. In general, regions with loosely and
densely packed particles can both be present within a
mono-dispersed layer or sub-layer.
[0351] FIG. 26 shows an example of a composite material 2600 that
provides a gradient that changes direction similar to FIG. 9.
Specifically, composite material 2600 includes two symmetric layer
sequences 2600A and 2600B as shown in FIG. 25 for composite
material 2500 that are attached to each other at the small-particle
side, thereby forming a multi-particle layer 2610 comprising two
mono-dispersed sub-layers 2610A and 2610B (being a two layer
densely packed particle structure) in the middle of composite
material 2600.
[0352] Similarly for concentric configurations as shown generally
in FIG. 6, a specific embodiment of a concentric composite material
(a concentrically layered particle structure 2700) is shown in FIG.
27 that includes a mono-dispersed layer and a multi-particle layer,
which are oriented concentrically around a central particle 2710.
Central particle 2710 is surrounded by a multi-particle layer of a
densely packed sub-layer of particles 2720A and a loosely packed
sub-layer of particles 2720B. As a surface layer, a mono-dispersed
layer includes loosely packed plurality of particles 2730 that
partially fill the space between loosely packed particles 2720B.
Thus, the mono-dispersed layer overlaps partly with the loosely
packed sub-layer. Central particle 2710, sub-layers 2720A, 2720B,
and mono-dispersed layer 2730 form a gradient layer structure with
decreasing particle size with increasing radial distance from the
center of central particle 2710. In some configurations, sub-layers
2720A, 2720B are representative for a two layer densely packed
particle structures and mono-dispersed layer 2730 does not need to
be representative for mono-dispersed layers of a gradient. In some
configurations, sub-layers 2720A, 2720B arc not representative for
a densely packed particle structure but mono-dispersed layer 2730
is representative for densely packed particle structures.
[0353] In contrast, a concentrically layered particle structure
2800 is shown in FIG. 28 that is configured to form a gradient
layer structure having increasing particle size with increasing
radial distance from the center of central particle 2810 with the
exception of that central particle 2810 being the largest particle.
Concentrically layered particle structure 2800 includes further a
layer with the two densely packed mono-dispersed sub-layers 2820A,
2820B and a densely packed mono-dispersed layer 2830 is shown as a
surface layer. Similar consideration with respect to the
interpretation of the structure can be done as above for FIG.
27.
[0354] While FIGS. 27 and 28 specifically describe multi-particle
layers for concentric layer structures, FIGS. 29 to 32 describe
multi-particle layers for planar layer structures.
[0355] In particular, FIG. 29 shows a composite material 2900 of 6
multi-particle layers applied to a glass or polycarbonate substrate
2970. The mean particle size multi-particle layers decreases with
increasing distance to substrate 2970. Specifically, composite
material 2900 includes multi-particle layer 2910 comprising 3
sub-layers of 320 nm polystyrene particles, multi-particle layer
2920 comprising 4 sub-layers of 260 nm polystyrene particles, and
multi-particle layer 2930 comprising 5 sub-layers of 220 nm
polystyrene particles. Multi-particle layers 2910 to 2930 are
hexagonal close packed (hcp) layers. Gradient layer structure 2900
includes further multi-particle layer 2940 comprising 6 sub-layers
of 160 nm polystyrene particles, multi-particle layer 2950
comprising 4 sub-layers of 130 nm polystyrene particles, and
multi-particle layer 2960 comprising 2-4 sub-layers of 110 nm PMMA
particles. Multi-particle layers 2940 to 2960 are cubic close
packed (ccp) layers. While, for example, layers 2910 to 2920 may
act as densely packed particle structures, layers 2930 to 2960 may
act more like a gradient structure or visa-versa depending on the
physical properties of the particles. However, this structure is
only exemplary to illustrate the various aspects of densely packed
particle structures and gradient structures. In principal, densely
packed particle structures may include large numbers of layers
comparable to the number of gradient layers.
[0356] Composite material 2900 is held together without a binding
material. It is assumed that the binding is caused be hydrogen
bonding of acidic functions of the material.
[0357] Composite material 2900 can be produced by spin coating
using particle concentrations of about 2.5% for layers comprising
3-4 sub-layers. It has been found that lower concentrations of
about 1% for larger particles (larger than 200 nm) can yield
mono-dispersed layer or a layers comprising 2 sub-layers. The
particle dispersions are based on 1/3 water and 2/3 methanol.
[0358] Thus, it is assumed that the concentration of the particles
allows controlling the number of sub-layers. Moreover, it is
assumed that the size of the particles affects the structural
packing of the particles within a layer (hcp and ccp).
[0359] FIG. 30 shows a schematic presentation of a 6 composite
material 3000. Each layer can be a multi-particle layer or a
mono-dispersed layer. An example of a composite material 3000 can
comprise polystyrene particles of 320 nm, 260 nm, and 220 nm
diameter in layers 3010, 3020, and 3030, respectively. Layer 3040
can include 160 nm PS particles and/or 160 nm silica particles.
Alternatively, layer 3040 can include 140 nm PMMA particles. Layer
3050 can include 140 nm PMMA particles, 130 nm PS particles, or 110
nm PMMA particles. Layer 3060 can comprise 110 nm PMMA particles.
In some embodiments, layer 3060 comprises 260 nm PS particles.
[0360] FIG. 31 shows a 9-layer composite material 3100 that
includes two 5 layer gradients. The particles of the various switch
from hcp configuration to ccp configuration and back as the size
changes. All particles are made of polystyrene with --COOH
functionality. All layers indicated as mono-dispersed layer can
also be multi-particle layers and vice versa, which may not change
the packing structure. In particular, gradient structure 3100
includes a layer 3110 of 130 nm particles, a layer 3120 of 160 nm
particles, a layer 3130 of 220 nm particles, a layer 3140 of 260 nm
particles, and a layer 3150 of 320 nm particles. An inverted
sequence of similar layers follows layer 3150.
[0361] As can be seen in the lower right corner, smaller particles
can fill loosely packed areas of larger particle layers, thereby
initiating islands of specifically packed particles. The packing
structure can assimilate within close packed sub-layers.
[0362] FIG. 32 shows a composite material 3200 with an alternating
gradient direction. Specifically, the composite material 3200
includes 17 layers that form four regions of non-alternating
gradients based on a change in particle size of neighboring layers
of about 20%. All particles are polystyrene nanospheres with --COOH
functionality. Only a single layer of particles is shown for each
of the three larger particles layers 3210, 3220, and 3230 as well
as for the layer of smallest particles 3250. A multi-particle layer
3240 of two densely packed sub-layers is shown.
[0363] The composite materials of FIGS. 30 to 32 can be considered
to include densely packed particle structures if one assumes one of
the layers to be representative for a multi-particle layer.
Alternatively or additionally, one can apply to the sides of the
gradient structures to form a composite material with gradient
structure and densely packed particle structures.
[0364] As described above, any of the described composite material
can further include core-shell particles as, for example, described
in connection with FIGS. 11, 13, 14, 17, 22, and 24 as a separate
layer(s) and/or as part of the gradient layer structure itself or
densely packed particle structures. For example, filled core-shell
particles of polystyrene can replace the layers of larger
particles, e.g., of the 320 nm, 260 nm and 220 nm particles of FIG.
31.
[0365] In general, composite materials can include, for example,
layers of mono-dispersed particles, layers of mono-dispersed
core-shell particles, multi-particle layers, multi-particle layers
including sub-layers of core-shell particles, multi-core-shell
particle layers, and multi-core-shell particle layers including
sub-layers of non-core-shell particles.
[0366] In some embodiments, the composite materials based on layers
of mono-dispersed particles, layers of mono-dispersed core-shell
particles, multi-particle layers, multi-particle layers including
sub-layers of core-shell particles, multi-core-shell particle
layers, and multi-core-shell particle layers including sub-layers
of non-core-shell particles can be formed with or without
intermediary material. Additionally or alternatively, intermediary
material may be only used for binding layers of the larger (or
smaller) particles of, e.g., a gradient layer structure. Moreover,
intermediary material may be only used in some areas and not in
others.
[0367] In various applications, the composite materials based on
layers of mono-dispersed particles, layers of mono-dispersed
core-shell particles, multi-particle layers, multi-particle layers
including sub-layers of core-shell particles, multi-core-shell
particle layers, and multi-core-shell particle layers including
sub-layers of non-core-shell particles can be applied to devices
such as containers as shown in FIGS. 15 and 24 as examples for
waste receptacles. These composite material can further applied to
fibers and used in connection with textiles as discussed in
connection with FIGS. 16 and 17. Textile applications can include
textiles for use in firefighting, law enforcement, military,
defense, sports, and fashion. Such cloth or film can be suitable
for forming uniforms, helmets, helmet liners, helmet liner pads
etc. that exhibit the beneficial effect of reacting to
environmental changes in a predetermined manner. Specific examples
can include inner liners for uniforms or jackets that can be
attachable and/or fused into the cloth.
[0368] Additional applications, can involve the suppression of
compression waves (including shock waves) in pipes. Shock waves
are, for example, generated through valve operation in oil
pipelines as discussed in connection with FIG. 18. The composite
material can further be applied to surfaces that require impact
resistance. Examples include housing of hand held devices, helmets,
vehicles or components thereof, as discussed in connection with
FIGS. 19, 21 to 24. The composite material in those applications
can be applied as a coating and/or provided as a liner. The
composite material can further be used in connection with cushions,
for example, the helmet pads shown in FIG. 21.
[0369] In the following, a large variety of materials are discussed
that can be applied in the composite material, specifically, for
the solid particles and core-shell particles. In general, the
composite material can include particles of the same (single
material system) or various different materials. In various
embodiments, suitable particles can comprise silica; porous silica;
aluminum hydroxide; polymeric materials; ceramic polycarbonate;
metal and metal alloy spheres; perlite, carbonate; bicarbonate and
halide salts; ceramics; silicates; chelators, such as, for example,
calcium or EDTA; foams or foam generating reagents, or a
combination thereof.
[0370] Fire suppression can be achieved with particles comprising
one or more of potassium bicarbonate, aluminum, magnesium
hydroxide, surfactants, aluminum hydroxide, potassium bicarbonate,
halocarbons, potassium iodide, lithium carbonate, sodium carbonate,
sodium hypochlorite, potassium nitrate, magnesium hydroxide and
various other hydrates, fluorocarbon surfactants, hydrocarbon
surfactants, hydroflurocarbons (HFCs), pentabromodiphenyl ether,
antimony trioxide, halocarbons, chlorinated and brominated
materials (polybrominated diphenyl ether (PBDE or DecaBDE, OCtaBDE,
PentaBDE), polybrominated biphenyl (PBB) and brominated
cyclohydrocarbons), and urethane.
[0371] For example, core materials that can be used for fire
retardance or suppression include hydroxides and hydrates,
halocarbons, carbonate, bicarbonate, halide and nitrate salts,
polybrominated materials, surfactants and hydrofluorcarbons. In
particular, aluminum hydroxide can break down under heat to provide
two primary methods for extinguishing a fire ball associated with a
bomb blast. First, it expels water vapor upon thermal breakdown
which assists in quenching the fire. Additionally, the thermal
breakdown process is endothermic and can thus absorb a large amount
of heat resulting from the blast zone. Still further, the resultant
material, after break down is an alumina (Al.sub.2O.sub.3), the
presence of which can form a protective layer against the spread of
fire. Still further, the inert gases produced (water and carbon
dioxide) can also act as diluents in the combusting gas,
effectively lowering the partial pressure of oxygen which slows the
reaction rate.
[0372] In applications coupled with textiles,
Tetrakis(hydroxymethyl)phosphonium salts can be used as core
material
[0373] Moreover, ZrO.sub.2 eruptively generated aerosol can serve
as the anti-explosion and fireproof agent, and therefore, can be
applied in security applications.
[0374] In some embodiments, Hydroflurocarbons (HFCs) can be used
for fire suppression. In particular, a series of HFCs are
commercially available from Dupont.RTM. that offer fire suppression
with little or no ozone depletion. In some embodiments,
pentabromodiphenyl ether can be used as a core fire retardant
(eventually in conjunction with antimony trioxide). Still further,
halocarbons can also be used as flame retardants core
materials.
[0375] In some embodiments, chlorinated and brominated materials
can also be used as fire retardant core materials. These materials
can release hydrogen chloride and hydrogen bromide during thermal
degradation. These react with H* and OH* radicals in the flame
resulting in the formation of inert molecules and Cl* or Br*
radicals. The halogen radicals have lower energy than H* and OH*
and therefore reduce the propagation of the flame (reduction in
oxidation potential). Antimony can also be used with halogenated
flame retardants. Brominated flame retardants are produced
synthetically in over 70 variants and are considered to be
effective flame retardants. Any of the three classes of the
brominated flame retardants can be separated into three classes or
families: polybrominated diphenyl ether, polybrominated biphenyl,
and brominated cyclohydrocarbons.
[0376] Fluorocarbon surfactants and hydrocarbon surfactants can
also be used as flame retardants. For example, the fluorocarbon
surfactants disclosed and described in U.S. Pat. Nos. 4,090,967 and
4,014,926, the entire disclosure of which are hereby incorporated
by reference, can be used for coating gas lines and gas containing
receptacles. These materials can produce foam that spreads over a
surface, effectively suppressing the vaporization of gasoline.
These foams can have, for example, an expansion ratio of between
50/1 to 1000/1. In order to mitigate and/or remediate a radioactive
or "dirty" environment, potassium iodide can be used as a core
material to mitigate and/or remediate, for example, radioactive
iodine 131, which is known to cause thyroid cancer. Other core
materials suitable for use in radioactive remediation include the
known family of chelators. Chelators are materials that can
selectively bind to radioactive metals. Two exemplary chelators
commercially available in relatively large quantities are calcium
and EDTA. In some embodiments, one or more particle layers of the
composite material can comprise an inert material, such as, for
example, a porous silica particle. To that end, porous silica can
offer exceptional absorption characteristics.
[0377] Foam generating composite materials can be applied in
applications such as petroleum/oil based conveyance systems,
refining operations, chemical conveyance systems, and storage
systems (e.g., as clotting or sealing material). As core-materials
or particle materials, the foam generating composite material can
then include, for example, epoxy materials (resin and hardener),
which requires activation, an activating material, and a foaming
agent. In addition, a reinforcing material, e.g., carbon fibers can
be provided to be penetrated by the foam. Exemplary foaming agents
include Telomer-based materials such as fluorosurfactants, aqueous
film-forming foam (AFFF), alcohol-resistant aqueous film-forming
foam (AR-AFFF), fluoroprotein (FP), film-forming fluoroprotein
(FFFP), and alcohol-resistant film-forming fluoroprotein (AR-FFFP).
Fluorosurfactants are based on perfluorinated telomer chemistry.
Foaming agents can further include polyurethane, polyethylene,
cross-linked, polystyrene, and urethane.
[0378] Composite materials for helmet liners or helmet liner pads
can include, for example, latex based foam systems that require a
latex solution as dissolved polymer, the foaming agent, a curative
and a gel, as well as a fire retardant (e.g., one of the
polybrominated class).
[0379] In some embodiments, the composite material can provide
shielding against RF signals to assist in the prevention of a
remote detonation. For example, an RF shielding layer can be
provided by incorporating a conductive element in one or more of
the particle layers. A number of materials are known to be capable
of providing RF shielding, including, for example, copper and
nickel. By incorporating electrically conductive and/or
electromagnetic radiation absorptive particles into one or more
layers, an RF signal can be shielded thus inhibiting the ability
for remote detonation of an explosive device.
[0380] In some embodiments, one or more layers can comprise a
piezoelectric material. According to this embodiment, the
piezoelectric material can interact with vibrations of the
surrounding environment to produce electricity. For example,
acoustic waves could be used to attenuate a material designed as
described so that piezoelectric materials in one of the layers are
utilized to produce electricity. The produced electricity can then
be harnessed for use internally by one or more layers of the
composite material or can be used external to the material.
[0381] It should be understood that any one or more layers of the
composite material can be customized to interact with or react to
changes in the surrounding environment in a predetermined manner.
To that end, the selection of materials depends on the particular
predetermined interaction or reaction that is desired.
[0382] Production of particles, such as, for example, core-shell
particles, can comprise a solvent cast process, a continuous
solvent cast process, an extrusion process, and a combination
thereof. In some embodiment, such a process can require that the
material and/or precursor materials be at least partially soluble
in a volatile solvent or water; remain stable in solution with a
reasonable minimum solid content and viscosity; and be capable of
forming a homogeneous film and/or an in-situ gradient, and
releasing from a casting support.
[0383] For selected core or agent materials, the microcapsules can
be manufactured by conventional micro-encapsulation technique.
Micro-encapsulation is defined as a process by which clusters of a
solids, liquids or gases are packaged within a shell material.
Micro-encapsulation is commonly distinguished as either a chemical
or physical process. Both processes can be used to produce the core
shell structures.
[0384] In some embodiments, the microcapsules can be formed from a
conventional polymer or polycarbonate composition. It should be
appreciated that such polymers and polycarbonates are further
customizable in that they can be produced with a variety of
physical attributes. For example, microcapsules can be manufactured
having specifically desired strengths, elastic coefficients,
colors, and thicknesses. The use of polymers can also offer energy
absorbing characteristics as they decrease deflection of
compression and sound waves. Further, polycarbonates can be used as
a transparent material and ceramic/polycarbonate composite
materials can be used, for example, in specific applications where
increased levels of shielding (emf, induction, radiation etc.) are
desired.
[0385] Exemplary chemical micro-encapsulation techniques that can
be used to manufacture the encapsulated core-shell particles
include polycondensation (interfacial polymerization), colloidosome
formation, polymer precipitation by phase separation,
layer-by-layer polyelectrolyte deposition, surface polymerization
and copolymer vesicle formation. Likewise, exemplary physical micro
encapsulation techniques include centrifugal extrusion, fluid bed,
a Wurster process, and pan coating. In addition, centrifugal
extrusion techniques can be used to produce larger particles, such
as those ranging from about 250 micrometers to about a few
millimeters in size.
[0386] In addition to the microencapsulated core-shell particles
described above, one or more layers of the composite material can
also comprise any of the core materials described above without the
core or shell encapsulation coating. In addition, one or more
layers can also comprise the microencapsulated shell coatings
described above, in the absence of the core material.
[0387] The shell of a core-shell particle can be produced using a
variety of processes. In various embodiments, the process used for
the production of a core-shell particle can comprise FBE powder
coating/lining; metallizing; electrostatic spray; dip coating;
organic coating; parylene coating; spray coating; screen coating;
roller, spin coating, extrusion processes, passive adsorption,
covalent coupling, or any combinations thereof. In some
embodiments, the process used for the production of a core-shell
particle can comprise the one or more of the following techniques
and/or material systems: polymers, for example, but not limited to
baked phenolic, elastomeric urethane, epoxy, polyurethane, vinyl
ester, polyester, polystyrene, or any combinations thereof.
[0388] It should be appreciated that any individual encapsulation
method can be suitable for the production for particle sizes having
a specific size range and that one or more methods can be suitable
for the production of a specific size particle. Exemplary
encapsulation methods and particle size ranges are detailed in
Table 2 below. It should be appreciated that the recited ranges are
not limiting and can vary.
TABLE-US-00002 TABLE 2 Encapsulation Method Size Range (.mu.m)
Physical Methods Stationary co-extrusion 1,000-6,000 Centrifugal
co-extrusion 125-3,000 Submerged nozzle co- 700-8,000 extrusion
Vibrating nozzle >150 Rotating disk 5-1,000 Pan Coating >500
Fluid bed 50-10,000 Spray drying 20-150 Chemical Methods
Simple/Complex coacervation 1-500 Phase Separation 1-500
Interfacial polymerization 1-500 Solvent evaporation 1-500 In-situ
polymerization 1-500 Liposome 0.1-1 Sol-gel methods 0.1-1
Nanoencapsulation <1
[0389] The multilayered composite material can be manufactured by a
number of techniques. Initially, once the selection of particles
and the corresponding particle sizes are determined for a given
layer, these particles can be suspended in a liquid vehicle system
or medium to form a batch composition for the given layer. The
batch composition can then be used to form a layer of the material
on a substrate. In one embodiment, it is contemplated that the
succesive layers of the composite material can be applied as a film
or coating to the substrate. Accordingly, a batch composition for
each given layer can be provided and successivly applied to a
surface of the substrate. Deposition techniques can include, for
example, chemical vapor deposition, electrophoretic deposition,
plasma enhanced vapor deposition, spin-coating, dip coating,
flexographic printing, spread coating, sequential spray, foaming,
spray coatings, casting, slurry based processes, and sequential
processes. Those techniques can allow, for example, the production
of waste receptacles and transparent liners. Dip coating,
flexographic printing, and knife-edge layering can be applied, for
example, for the production of commercial quantities. Spin-coating
can be used, for example, to produce samples for experiments.
[0390] In some embodiments, it is also contemplated that the
composite material can be manufactured as a stand alone article
without requiring it to be applied to or supported by a substrate.
For example, successive batch compositions can be used to form
multiple plys of a stand alone film. Alternatively, batch
compositions can also be used to manufacture molded articles such
as for example, injection molded, extrusion molded, and blow molded
articles.
[0391] The batch composition for providing a given layer of the
composite material can comprise a plurality of the desired
particles suspended or dispersed in a suitable liquid vehicle
system or medium. The liquid vehicle system can be formulated based
upon any one of the following stabilization techniques including
electrostatic stabilization, steric stabilization, electrosteric
stabilization, depletion stabilization, stabilization by masking
van der Waals forces, and stabilization by hydration forces. The
stabilization mechanisms work by preventing or hindering the
flocculation of the particles in suspension. In some embodiments,
it is preferred for the liquid vehicle stabilization techniques to
be an electrostatic or electrosteric stabilization. Electrostatic
stabilization uses ions in solution to generate like charges on the
particles in suspension. Electrosteric stabilization uses a charged
polymer that adsorbs on the particle surfaces, causing double-layer
repulsion. Either technique can be used to stabilize a suspension.
Further, exemplary particles in liquid vehicle dispersions can be
produced in aqueous form or from other suitable mediums that have
low volatility and suitable thermal stability, such as for example,
ethylene glycol.
[0392] For electrostatic stabilization, an acid or base (the choice
of which can be dependant upon the charge of the particle surfaces)
can be added to an aqueous suspension. The addition can adjust the
pH of the suspension, which can affect the charge on the particle
shear planes, i.e., the zeta potential. If the particle surface has
a positive charge, adding an acid to the suspension decreases
viscosity effectively increasing the magnitude of the
zeta-potential. When acid is added to the suspension, the particle
shear planes develop a net negative charge, causing the particles
to repel each other. The opposite is true for a suspension of
negatively charged surfaces to which a base can be added to give
the particle shear planes a net positive charge and in order to
suitably disperse the particles in the suspension.
[0393] For electrosteric stabilization, the presence of a
dispersant can directly influence the stability of the suspension
until the particle surfaces are completely covered. Dispersants can
be added in relation to the particles surface area, charge and size
of the particles ensuring the correct amount of coverage. For
example, in some embodiments, a polyelectrolyte dispersant should
have the opposite charge of the particle surface being dispersed.
The addition of a polyelectrolyte can change the isoelectric point
allowing a dispersion to result without the need to adjust the pH
of the suspension. When added to a suspension near the point of
zero charge, the water used in the suspension can have a greater
affinity for itself than the polymer, and hence the polymer can
adhere to the particle surfaces. To prevent coagulation, an ionic
solution can also be added to an electrosterically stabilized
suspension to counter act the charge buildup. To that end, it
should be understood that a stable suspension can be important as
it can allow a higher solids loading with lower apparent viscosity
than an unstable suspension can allow.
[0394] Still further, the batch compositions can comprise additives
such as colorants, biocides, surfactants, plasticizers, binders,
dispersants, acid, base, pore formers, and the like. Additionally,
it should also be understood that the batch compositions can be
formulated to provide transparent, translucent, or even opaque
composite materials. For example, it can be desired for the
composite material to be transparent. This can enable the
manufacture of, for example, a transparatent film, liner or,
alternatively, a composition that can be applied to glass or
similar substrates without affecting the pre-existing transparancy
of the substrate upon which it is applied. Alternatively, it can be
preferred for the composite material to have a predetermined color
suitable for use in forming stand alone articles or coatings having
certain aesthitic appearances.
[0395] As summarized above, it is further contemplated that the
composite materials can be used in a variety end use applications
including, for example, military, energy and related
infrastructure, electronics, sensors and actuators, lubricants,
medical applications, catalysis, structural materials, ceramics,
civil engineering applications, aerospace, automotive applications,
textile and antiballistic materials. In some embodiments, it is
contemplated that the composite material is particularly well
suited for use as or in combination with an antiballistic
material.
[0396] In some embodiments, a composite material can be applied
onto the surface of any desired object in order to provide the
blast energy absorption and any secondary blast mitigation effects
described herein. For example, the material can be applied to the
inside surface of a trash receptacle. Alternatively, the material
can be provided in the form of a stand alone film that is suitable
for use in manufacturing liners that can be removably placed inside
pre-existing trash receptacles. The liner can be manufactured
having any predetermined color. Alternatively or in addition, the
liner can also be transparent. Still further, it is also
contemplated that the composite material can be used to form the
trash receptacle itself thus eliminating the need to apply either a
separate coating or a liner in order to provide the blast energy
absorption and any secondary blast mitigation effects described
herein. Once again, the manufactured trash receptacle can also have
any predetermined color or be transparent.
[0397] Thus, the response of the composite material can be
considered to be smart in that it does have a designed or
engineered response to an external stimulus. Specifically, the
properties of the composite material adapt in response to the
external stimulus. The composite material can be further provided
to be multifunctional, e.g., include multiple features such as
absorption of compression waves, mitigation of fire, remediation of
biological systems etc.
EXAMPLES
[0398] The invention is further described in the following
examples, which do not limit the scope of the invention described
in the claims.
Prophetic Example 1
Exemplary Batch Composition
[0399] In an exemplary embodiment, a composite material could be
comprised of a plurality of tape casted layers. The tape casting
could be used to apply the composite material layers to a
pre-existing substrate or to form a stand alone multi-layered
composite material. An exemplary and non-limiting batch composition
that could be used to prepare each successive layer of the
composite material is set forth below in Table 3:
TABLE-US-00003 TABLE 3 Component wt % Function Microspheres 55.66
Layer 1 Xylene 18.55 Solvent Ethanol 18.55 Solvent Butvar 98.sup.1
4.08 Binder Menhaden 1.12 Dispersant oil Santicizer 1.02
Plasticizer 160.sup.2 UCON.sup.3 1.02 Plasticizer
.sup.1Commercially available from Electron Microscopy Sciences,
Hatfield, Pennsylvania; .sup.2Commercially available from the Ferro
Corporation, Walton Hills, Ohio; .sup.3Commercially available from
Dow Chemicals, Midland Michigan
[0400] Based upon the formulation set forth in Table 3, the
microspheres, solvents and dispersant can first be mixed in a
ball-mill for approximately 24 hours. After mixing in the ball
mill, the binder and plasticizer component can then be added to the
ball mill and the resulting mixture can be mixed for another 24
hour period. After mixing is completed, the composition can be tape
cast onto a coated paper or a steel belt to form a particle layer.
The tape casting can be performed by using a commercially available
tape casting apparatus such as a Unicast 2000. The tape cast layer
can then be allowed to dry naturally under ambient conditions. This
process can be repeated using batch compositions comprised of
particles having differing median particle sizes until a desired
number of particle layers have been tape cast to form the particle
size gradients and densely packed particle structures described
herein.
Prophetic Example 2
Use as a Blast Wave Absorbing Material
[0401] With reference to FIG. 1, the material of the composite
material can be used as a blast wave absorbing material. For
example, a material manufactured according to prophetic example 1
can be disposed on the interior surface of a waste receptacle so
that the layer 110 comprising the largest median particle size is
oriented to be the first layer exposed to the impact of the bomb
blast shock wave. The layers comprised of smallest particles, layer
170, would be position or located adjacent to the waste receptacle
wall. The layers 110, 120, and 130 can be comprised of particles
having the core-shell microstructure as depicted in FIG. 11. The
shell 1120 of the material can be pliable such that it can deform
upon impact of a bomb blast (shock wave 20). The particle cores can
be comprised of one or more blast mitigating materials, such as
sodium hypochlorite, potassium nitrate, and the like. Layer 140 can
comprise a RF shielding material (such as copper, nickel, copper
and nickel alloys, cermets, and the like). The adjacent remaining
layers 150, 160 and 170 can be comprised of particulate materials,
such as a porous silica, whose median particle size distribution
allows a sufficient increase in the inter layer particle contact
points to efficiently reduce the impact 105 across the material 100
and the remaining layers (150, 160 and 170).
[0402] Upon impact of the shock wave 20, the core-shells in layers
110, 120 and 130 can deform and a portion of the energy associated
with the bomb blast can be removed from the system due to this
deformation. As the shells deform, they can also apply pressure to
the adjacent particles upon which they contact, thus, transferring
impact energy to the energy required for deformation and angular
pressure on its neighboring particles. Ultimately the shells 1120
deform to a point where shell rupture occurs releasing the core
fire retardant materials directly into the blast zone. As the
core-shell particles rupture in successive layers, the cores from
different particles are introduced into the blast zone, which can
further enable, if desired, more complex systems or combinations of
systems to be introduced, thus allowing sequential reactions to
occur in a user defined manner. The staggering of core materials in
a pre-designed manner allows sequential reactions whose sum
reaction is greater than their individual contributions.
[0403] In addition to the core-shell rupturing, as the shock wave
20 traverses across the first layer 110, it would reach the
interface between the first layer 110 and the second layer 120. As
the particles comprising the first layer 110 are larger than the
particles populating the second layer 120, there also exists at the
interface an increase in surface contact points. As in the case of
the first layer 110, the impact energy, deforms, compresses and
re-orientates the individual particles comprising the second layer
120 resulting in a reduction of the energy of the impact 105. The
deformation, compression, re-orientation and transfer of energy
relationships continues across the cross section of the material
100 and though subsequent layers from layers 120 to 130, 130 to
140, 140 to 150, 150 to 160 and 160 to 170.
Prophetic Example 3
Experimental Design
[0404] In some embodiments, a composite material could be comprised
of encapsulated materials having particle sizes of 500 nm, 5 .mu.m,
and 50 .mu.m. The mean particle diameter and the tensile strength
of a particulate filled rigid polyurethane resin at a given volume
fraction can be expressed as a linear relationship. In addition,
the ability of the particle to flow and compress decreases with
average particle size, while strength and transverse rupture
strength (TRS) increase with decreasing particle size.
[0405] A unique slope of the linear relationship between friction
angle and void ration was identified for monosize specimens of
varying particle shapes. It was also observed that the friction
angle decreases as the aspect ratio increases provided that the
void ratio of the two specimens was the same. The friction angle
was proportional to the coordination number for monosize specimens
regardless of individual specimen size.
[0406] Testing protocols for a composite material produced in
accordance with the present invention can include: 1) shock tube
analysis wherein shock waves are generated by the rupture of a thin
diagram separating high and low pressure gases, wherein samples are
mounted at the end of a tube; 2) simulations of blast effects using
small (e.g., gram range) explosive charges, scaling models, and
optical shock wave imaging techniques, wherein shock waves are
simulated using scaling law; and 3) detonation techniques wherein
the velocity at which a detonation wave travels through the
explosive product is determined, typically in the range of from
about 2,000 to about 8,000 m/s.
[0407] It should be appreciated that several types of experimental
designs can be investigated. For example, experimental designs
based upon particles can be investigated. The primary input of
energy occurs via the interaction of clusters, molecules, atoms, or
ions with a surface. The amount of transferred energy ranges from
eV to a few keV. Energy dissipation processes can be studied by
means of spectroscopic techniques and laser interferometry. These
experiments are not time resolved, but rather quasi-stationary.
Dynamics can also be investigated. For example, a dynamic
observation can be made of the energy dissipation process requiring
excitation of a surface via an ultra-short laser pulse providing
photon energies of a few eV. Using a pump-probe technique with a
second delayed pulse can probe the reaction of a system upon
excitation. Analysis techniques can include diffraction,
spectroscopic techniques, laser interferometry, and various imaging
techniques. Still further, effects of friction can also be
investigated. This can include a study of the transport of
particles and electrons at surfaces and in thin layers,
particularly energy dissipation due to both mechanical friction and
friction due to scattering at the surface and interfaces. Friction
analysis techniques can include spectroscopic and imaging
techniques.
Example 4
Preparation of a Multilayer Composite Materials
[0408] Various types of multilayer composite materials were
produced by spin-coating various layers of particles on a
polycarbonate substrate. The polycarbonate substrate had a
thickness of about 1 mm but in general the thickness of the
substrate can vary and be adapted, for example, to the
application.
[0409] To increase the adhesion of the first layer of particles,
the polycarbonate substrate was irradiated with a mercury lamp
using the ultraviolet transition at 253.7 nm. In the presence of
air, the oxygen of the air reacted under the irradiation to create
oxygen containing radicals at the surface of the polycarbonate. The
final product of the reaction is an organic acid functionality at
the surface that renders the surface hydrophilic and provides a
hydrogen-bonding surface upon which the layers of the
nanostructures were built. The time period of UV irradiation was
about 30-60 minutes, usually about one hour.
[0410] After irradiation, the polycarbonate substrate was
transferred to a spin coater and a first layer of particles was
deposited. As particles, nanospheres were provided with carboxylic
acid functionality on the surface (polystyrene particles) or polar
in nature (silica and PMMA).
[0411] All nanospheres were provided in a mixture of 25% water and
75% methanol. Due to the small size and their repulsion due to
their polarity, most of the nanospheres did not aggregate. If
aggregation was present, particles settled out of the suspension.
Then, the dispersion was placed in a sonicator to break up the
aggregates and redisperse the nanospheres. All dispersions
contained 2.5% nanospheres, thereby providing one to two layers of
nanospheres in the film. If more particles in a layer were desired,
the particle concentration was increased to 5%.
[0412] The spin coater was operated in a two step sequence after 75
.mu.l of nanospheres suspension were placed on the substrate. The
first step lasted 5 seconds and the substrate was spun at 300 rpm
to spread the dispersion over the entire substrate. The spin coater
speed was then increased to 4000 rpm (2000 rpm, if the 5% solution
was used) for one minute.
[0413] The substrate with the layer was removed and heated at
50.degree. C. for 5 minutes to aid in evaporating the solvent. In a
test run, five different layers of nanospheres were added before
the heating step, which worked just as effectively. The multilayer
composite material was built up in this way until the desired
number of layers was deposited. Before testing, the samples were
stored for a day. The concentration of 2.5% corresponded to a
dilution of between 1:4 and 1:8 of the provided stock
solutions.
[0414] The spin coating proved to be a good technique to produce
lab samples of various gradient structures and densely packed
particle structures. Spin coating allowed generating multilayer
gradients using monolayers or multiple layers of each different
size particle used in the gradient by adjusting the concentration
of nanoparticles in the dispersion solution and/or the spin at
which the substrate was coated. The layer structures were confirmed
by profilometry, force microscopy and electron microscopy as
discussed below.
[0415] The following samples of gradient structures and densely
packed particles structures were produced on polycarbonate
substrates according the above described procedure: [0416] Samples
#01 and #02: Polycarbonate-130-160-220-260/130-160-220-260/etc. The
set of four layers was repeated eight times (32 layers in total).
[0417] Samples #03/#04:
Polycarbonate-130-160-220-260-220-160/130-160-220-260-220-160/etc.
The set of six layers was repeated five times (30 layers in total).
[0418] Samples #05/#06:
Polycarbonate-130-160-220-260-320-400-320-260-220-160/130-160-etc.
The set of ten layers was repeated three times (30 layers in
total). [0419] Sample #07: Polycarbonate-150-150-150-etc. The 150
nm layer was repeated 30 times (30 layers in total). [0420] Sample
#08: Polycarbonate-320-400/320-400/320-400/etc. The two layers were
repeated 13 times (26 layers in total). [0421] (Sample #09 as a
duplicate of sample #8 was not produced.) [0422] Sample #10:
Polycarbonate-400-320-260-220-160-130/400-320-260-220-160-130/400-320-etc-
. The set of six layers was repeated four times (24 layers in
total).
[0423] The samples were produced under conditions that created
layers having a thickness of one or two layers particles for each
size. The nanoparticles were characterized by their diameter in nm.
All nanospheres were solid polystyrene particles, except that the
400 nm particles were hollow polystyrene particles and the 150 nm
were solid silica particles.
[0424] The carboxylic acid functionalized nanoparticles, e.g.,
polystyrene or silica, formed a "bound" film by an assumed
interparticle hydrogen bonding. Essentially, there were
electrostatic interactions among the particles that made the layers
stay together. This was confirmed by removing an intact film from
the substrate with a piece of tape.
[0425] The coatings were transparent or, at the very least
translucent.
[0426] In FIG. 33, the particle size is plotted for the first
twelve layers to illustrate the gradient of the particles size
across the multilayer structure of sample #10. The particle size
varies in a saw-tooth-manner from the largest particle to the
smallest 130 nm solid nanosphere. A saw-tooth 3310, i.e., a
transition from large to small particles, corresponds to a region
with a gradient directed in the same direction and all saw-tooth
have the gradient in the same direction. In FIG. 33, the 400 nm
hollow spheres are indicated by circles 3320.
[0427] A cut view 3330 through the first two gradients is
schematically illustrated in the top right corner of FIG. 33.
[0428] Accordingly, the surface of the composite material according
to sample #10 is formed by the smallest particles.
[0429] In FIG. 34, the particle size is plotted versus the first 18
layers to illustrate the gradient of the particles size across the
multilayer structure of samples #05 and #06. The particles size
varies continuously from the smallest 130 nm particles to the
largest particles (the 400 nm hollow sphere are indicated by
reference number 3420) via the particles with the sizes 160 nm, 220
nm, 260 nm, 320 nm. Then the gradient direction changes and the
particle size decreases again down to the smallest 130 nm particles
via the particles with the sizes 320, 260 nm, 220 nm, and 160 nm.
Also in the structure shown in FIG. 34, the surface of the
composite material is formed by the smallest particles. Combining
the gradient structures (samples #1 to #6 and #10) and densely
packed particle structures (samples #7 and #8) can result in
layered composite materials with gradient structures and densely
packed particle structures.
Example 5
Impact Test of the Samples of Example 4
[0430] An impact tester was built using a weight (steel impactor)
that was dropped onto an assembly, e.g., a multilayer structure
sandwiched between two polycarbonate plates. The assembly was
attached below a tube that housed the weight, which can be dropped
from a predetermined height.
[0431] The impact tester comprised further a spring loaded sample
mount with a dynamic force sensor. The dynamic force sensor was
configured to detect the transmission of the shock through the
assembly. Specifically, the sensor detected the arrival of the
shock wave at, e.g., the edge of the gradient's substrate.
[0432] A comparison was performed between various assemblies: a) no
sample/no plates at all, b) two polycarbonate plates without
sample, and c) a sandwich of two plates with one of the samples
#01-#10 between the plates. Assemblies a) and b) were used as
controls to provide a reading of the true force, the force
transmitted though two pieces of blank polycarbonate. The controls
allowed for a measure of the effectiveness of the sample (assembly
c) in attenuating the shock. Specifically, the weight impacted the
top piece of polycarbonate, sending a shock wave into the gradient
film.
[0433] The plot of FIG. 35 overlays the three transmitted signals
as measured. In particular, signal 3510 corresponds to the
initiated shock wave as measured without sample and without plates,
signal 3520 corresponds to two polycarbonate plates without sample,
and signal 3530 corresponds to a sandwich of two plates with an
exemplary gradient sample between the plates.
[0434] As one can see, signals 3510, 3520, and 3530 differed in
their time of detection and in the maximum of the signal. Thus, the
sample delayed the shock wave and reduces its maximum.
[0435] For the various samples, the measurements were analyzed from
an oscilloscope using the maximum force detected by the sensor, the
width of the force peak and the time delay of the maximum force.
The data are summarized in Table 4 below and ordered according to
the reduction of the measured force.
TABLE-US-00004 TABLE 4 Width, Sample Max. Force, N ms Delay, ms
Bare sensor 1334 0.16 -- Polycarbonate x2 1156 0.27 0.10 #1/#2 872
0.31 0.18 (averaged) #3/#4 783 0.30 0.21 (averaged) #7 712 0.31
0.20 #10 712 0.30 0.21 #5/#6 623 0.34 0.22 (averaged) #8 578 0.34
0.24
[0436] According to the measurement, samples #01 and #02 with a
discontinuous gradient of small to large particles reduced the
force the least. Structures with incorporated hollow particles
reduced the force the more than gradient structures with only solid
particles. The densely packed particle structure of two particle
types (hollow core-shell and solid) in sample #08 with the most
hollow particles reduced the force the most. Second best were
samples #05 and #06, which comprised a continuous gradient and
included the hollow particles of 400 nm diameter. Also the densely
packed particle structure of a single particle configuration in
sample #07 reduced the force.
Example 6
Analysis of the Surface and Structure of Multilayer Composite
Materials
[0437] To analyze the surface and structure of gradient layers, two
types of gradient layer structures were produced using the method
as described in Example 4. The types differed in the direction of
the gradient. Specifically, five samples #11 with gradient
320-260-220-160-130-160-220-260-320 and three samples #12 with
gradients 130-160-220-260-320-260-220-160-130 were produced. One of
the goals of the analysis was to look at a cross section of the
gradient layer structure with an environmental scanning electron
microscope (SEM) and estimate the number of layers for each layer
of nanoparticles with a specific size. The parameters of the
production included a concentration of 2.5% (1:4 dilution) and
spinning at 4000 rpm.
[0438] FIGS. 36 to 39 show SEM images of the top surface and a
cross-section for samples #11 and #12. The SEM of FIG. 36 shows the
largest (320 nm) particles as the top layer. The top layer is
little disorganized. The 260 nm layer below the top layer seemed
closer to an hcp arrangement.
[0439] The SEM of FIG. 37 is the edge view of the same film
carefully broken and put into the microscope to look at the cross
section, i.e., the break. The break was not a clean brake. Most of
the layers going through the gradient could be identified. Looking
also at lower layers of the gradient layer structure, it was
estimated that the parameters resulted in gradient layer structures
comprising monolayers for each of the particle sizes (herein also
referred to as monolayer gradient). Accordingly, the applied
deposition conditions (1:4 dilution and 4000 rpm spin speed)
generated the monolayer gradients.
[0440] Based on the SEM measurement, the thickness was estimated to
be about 900 nm. Due to the close packing in direction of the
gradient, the sum of the sizes of the particles in each layer did
not equal the measured thickness.
[0441] As can be seen from similar SEM images reproduced in FIGS.
38 and 39, sample #12 was also produced as a monolayer gradient.
That can be seen, for example, in the cross sectional view shown in
FIG. 39. Based on the SEM measurement, the film was measured to be
about 800 nm thick.
[0442] To confirm the thickness measurement, the films of samples
#11 and #12 were measured using a profilometer. A section of the
film was removed and a stylus was moved across the film until it
moved to the bare substrate. Several measurements were taken and
averaged to compensate for variations in the film thickness and the
quality of the glass substrate. The average thickness for sample
#11 was 960 nm and the average thickness for sample #12 was 1030
nm. These values agree with the SEM measurements and confirms the
monolayer gradient structure.
Example 7
Hardness Test of Multilayer Composite Materials
[0443] To analyze the hardness of gradient layer structures, two
types of gradient layer structures were produced using the method
as described in Example 4. The types differed in the direction of
the gradient. Specifically, sample #13 included four alternating
gradients (with 17 layers in total) with particle sizes between 320
nm and 130 nm and between 130 nm and 320 nm. Sample #14 included
two gradients (with nine layers in total) with particle sizes
between 130 nm and 320nm and 320 nm and 130 nm. The parameters of
the production included a concentration of 2.5% (1:4 dilution) and
spinning at 4000 rpm. One of the goals of the analysis was to
characterize the surface hardness using nanoindentation--a
technique to measure hardness on the nanoscale.
[0444] Nanoindentation presses a pyramidal tip with dimensions of a
few tens of nanometers into the sample and measures the force
applied as a function of the depth to which the tip is pushed into
the sample. Multiple indentations were repeated at the same
location on the sample. Specifically, 19 cycles of indentation and
removal were made for the measurements. Measurements were made at
two surface locations on the composite materials. Four different
maximum force values at each surface location were used to allow
for different maximum depths for indentation into the film.
[0445] FIGS. 40 and 41 show hardness plots for the samples #13 and
#14, respectively, for a maximum force of 200 .mu.N. Schematic
representations 4010 and 4110 of the samples #13 and #14,
respectively, are included in the top right corner of the plots and
show that in sample #13 large particles form the surface, while in
sample #14 small particles form the surface. The plots are
representative for a series of measurements.
[0446] The force-depth curves were converted to nanohardness and
Young's modulus data as a function of indentation depth. Young's
modulus (E) is a measure of the stiffness of an elastic material
such as a polymer. It is the ratio of the stress over the strain in
the film and experimentally determined from the slope of a
stress-strain curve. Nanohardness is defined as resistance to
permanent or plastic deformation at the nano-micro level. Hardness
is a measure of resistance to an indentation. Both properties are
measurement technique dependent as there are different scales
depending on the equipment used. Data from nanoindentation
generally correlates with, but does not exactly agree numerically
with measurements on a macroscale.
[0447] Arbitrarily, a depth of 200 nm was selected for averaging
the values of hardness and elastic modulus for the four different
forces at that point. The results for the two sampling sites on
each of samples #13 and #14 were for sample #13: Hardness=0.050
GPa/0.045 GPa and Young's modulus=1.75 GPa/2.48 GPa and for sample
#14: Hardness=0.102 GPa/0.067 GPa and Young's modulus=2.87 GPa/4.12
GPa. For comparison, the literature values for polystyrene in bulk
from are Hardness=0.15 GPa and Modulus=2.2 GPa.
[0448] The derived nanohardness and Young's modulus seemed to
depend on the gradient-although the effect is not large as the
composite materials only comprised a two gradient structures. The
values for the small-to-large-to-small gradient differed from those
of the opposite orientation. The determined values were in the same
range as those for a bulk thin film of polystyrene, but the fact
that the two samples were different seemed to indicate that the
packing of the nanoparticles influences these properties.
[0449] It was further assumed that the gradient was better defined
away from the edge, i.e., in the center. In general, the films
appeared to be slightly harder than the bulk.
[0450] It is to be understood that while the invention has been
described in conjunction with the detailed description thereof, the
foregoing description is intended to illustrate and not limit the
scope of the invention, which is defined by the scope of the
appended claims. Other aspects, advantages, and modifications are
within the scope of the following claims.
* * * * *
References