U.S. patent application number 12/465663 was filed with the patent office on 2009-11-19 for carbon nanotube yarn, thread, rope, fabric and composite and methods of making the same.
Invention is credited to Jordan C. Bollander, Andrei Burnin, Christopher H. Cooper, Hai-Feng Zhang.
Application Number | 20090282802 12/465663 |
Document ID | / |
Family ID | 41314824 |
Filed Date | 2009-11-19 |
United States Patent
Application |
20090282802 |
Kind Code |
A1 |
Cooper; Christopher H. ; et
al. |
November 19, 2009 |
CARBON NANOTUBE YARN, THREAD, ROPE, FABRIC AND COMPOSITE AND
METHODS OF MAKING THE SAME
Abstract
There is disclosed a material comprising an assembly of at least
one spun yarn substantially comprising carbon nanotubes, a majority
of which are longer than one millimeter, such as longer than one
centimeter, chemically interlinked one to another, and arranged in
the morphology of spiral configurations. The disclosed materials
may take the form of a yarn, thread, rope, or fabric. There are
also disclosed composite materials constructed from the disclosed
materials.
Inventors: |
Cooper; Christopher H.;
(Windsor, VT) ; Zhang; Hai-Feng; (Winchester,
MA) ; Burnin; Andrei; (West Lebanon, NH) ;
Bollander; Jordan C.; (Claremont, NH) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
41314824 |
Appl. No.: |
12/465663 |
Filed: |
May 14, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61071748 |
May 15, 2008 |
|
|
|
Current U.S.
Class: |
57/238 ; 57/244;
977/742 |
Current CPC
Class: |
D02G 3/16 20130101; D10B
2101/122 20130101 |
Class at
Publication: |
57/238 ; 57/244;
977/742 |
International
Class: |
D02G 3/02 20060101
D02G003/02 |
Claims
1. A material comprising an assembly of at least one spun yarn
substantially comprising carbon nanotubes, wherein a majority of
the carbon nanotubes are longer than one millimeter, and are
chemically interlinked one to another.
2. The material of claim 1, wherein the chemical interlinking is
comprised of covalent bond, ionic bond, metallic bond, or
combinations thereof.
3. The material of claim 2, wherein the covalent bond links carbon
atoms belonging to backbones of two carbon nanotubes with no
involvement of intermediate atoms.
4. The material of claim 2, wherein the covalent bond between
nanotubes involves an intermediate moiety comprising of at least
one atom chosen from hydrogen, boron, carbon, nitrogen, oxygen,
aluminum, silicon, phosphorus, sulfur or combinations thereof.
5. The material of claim 2, wherein the ionic bond between
nanotubes involves intermediate moieties with opposite charges
comprising of at least one atom chosen from hydrogen, boron,
carbon, nitrogen, oxygen, phosphorus, sulfur or combinations
thereof.
6. The material of claim 2, wherein the metallic bonding between
nanotubes involves intermediate metallic moieties comprising of at
least one atom chosen from titanium, vanadium, chromium, nickel,
yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium,
palladium, silver, cadmium, indium, tin, rhenium, osmium, iridium,
platinum, gold, lead, bismuth or combinations thereof.
7. The material of claim 1, wherein the material comprises a yarn,
thread, rope, fabric, composite or combinations thereof.
8. The material of claim 7, wherein the composite material
comprises of thread, rope, fabric or combinations thereof.
9. The material of claim 7, wherein the composite is composed of
constituent material chosen from metals, natural and synthetic
polymeric materials, ceramic materials or combinations thereof.
10. The material of claim 9, wherein the constituent material is
chemically interlinked with the carbon nanotubes.
11. The material of claim 1, wherein the tensile strength of the
chemically linked, carbon nanotube spun yarn is between 0.1%-99%
that of the individual carbon nanotube from which it is
composed.
12. The material of claim 1, wherein a majority of the assembled
carbon nanotubes have a spiral morphology.
13. The material of claim 1, wherein the carbon nanotubes are not
embedded in a polymer matrix.
14. The material of claim 1, wherein the material comprises
different carbon nanotubes having at least two distinct properties
chosen from electrical, mechanical, thermal, and electromagnetic
properties.
15. The material of claim 1, wherein the material comprises carbon
nanotubes having at least one chemical functional group attached
thereto.
16. The material of claim 1, wherein a majority of the said carbon
nanotubes are longer than one centimeter.
17. The material of claim 1, wherein a majority of the said carbon
nanotubes are longer than ten centimeters.
Description
[0001] This application claims the benefit of domestic priority to
U.S. Provisional Patent Application Ser. No. 61/071,748 filed May
15, 2008, which is herein incorporated by reference in its
entirety.
[0002] Disclosed herein are materials comprising carbon nanotubes
that are spun into yarns, threads, ropes, fabrics and the like.
Methods of making such materials, as well as composites comprising
such materials are also disclosed
[0003] Metals and plastics have long been favorites for many
technical applications because of their versatile physical and
chemical properties including malleability, strength, durability,
and/or corrosion resistance. However for an increasing number of
applications, ultra-light materials exhibiting comparable or higher
strength, durability and/or conductivity are needed. To date, the
need for these materials has been primarily limited to high-tech
applications, such as high performance aerospace and high-end
electronics. However, they are becoming increasingly needed in
other areas as well, such as ballistic mitigation applications
(e.g. bulletproof vests, armor plating), and a wide range of
commercial applications involving heat sinks, air conditioning
units, computer casings, and vehicle bodies, to name a few.
[0004] Recent advances in materials science and nanotechnology have
led to the creation of a new class of carbon nanotube-based
materials with strength to weight ratios never before possible.
Carbon nanotubes and their unique properties have been known for
some time. Examples of literature disclosing carbon nanotubes
include, J. Catalysis, 37, 101 (1975); Journal of Crystal Growth
32, 35 (1976); "Formation of Filamentous Carbon", Chemistry of
Physics of Carbon, ed. Philip L. Walker, Jr. and Peter Thrower,
Vol. 14, Marcel Dekker, Inc, New York and Base 1, 1978; and U.S.
Pat. No. 4,663,230, issued Dec. 6, 1984. However, recent interest
in carbon filamentary material was stimulated by a paper by lijima
(1991) which made producing these materials possible. These early
studies and the work that has developed from them has resulted in
the discovery of a material with remarkable mechanical, electrical
and thermal properties that can be produced on the industrial
scale.
[0005] All of the carbon nanotube yarns produced to date, using the
techniques discussed above, were comprised of relatively short
carbon nanotubes (<1 mm), that did not specifically employ
chemical-linking between adjacent carbon nanotubes in order to
improve the strength of the yarn. The resulting prior art products
are unable to take advantage of the full benefits associated with
carbon nanotube. For example, while carbon nanotubes embedded in a
polymer matrix do add some multifunctional properties to the
composite, such as vibration dissipation, the polymer does not add
any improved property to the nanotube itself. Indeed, it is
typically difficult, if not impossible, to take advantage of the
properties of the carbon nanotube, such as tensile strength, when
they are dispersed in a polymer.
[0006] Furthermore, the prior art does not teach covalent bonding
of a substantially pure spun carbon nanotube thread with carbon
nanotubes in the millimeter length range. Present carbon
nanotube-based yarns, therefore, do not take advantage of the full
benefits associated with carbon nanotube. Thus, there is a need to
produce high strength yarns comprising carbon nanotubes that do not
suffer from the deficiencies of currently available yarns,
including a required polymer matrix to hold them together.
SUMMARY
[0007] In view of the foregoing, there is disclosed a material
comprising an assembly of at least one spun yarn substantially
comprising carbon nanotubes, wherein a majority of the carbon
nanotubes are longer than one millimeter, and are chemically
interlinked one to another. In one embodiment, the carbon nanotubes
are arranged in the morphology of spiral configurations.
[0008] There is also disclosed materials, such as thread, rope,
fabric and composite materials constructed from the carbon nanotube
yarns. The unique ability to spin carbon nanotubes in the form of
yarns without employing a polymer matrix between adjacent carbon
nanotubes leads the inventive materials to have a wide range of
application heretofore were unavailable. Such applications are able
to take advantage of the novel physical and chemical properties
derived from those of the carbon nanotubes.
[0009] Other aspects, advantages, and novel features of the present
invention will become apparent from the detailed description and
drawings provided below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1. SEM image of the raw carbon nanotube material
as-received from Nanotech Labs.
[0011] FIG. 2. Schematic drawings showing generic methods for
producing carbon nanotube yarn directly from aligned carbon
nanotube forest. (a) The carbon nanotube forest is being spun while
the yarn is drawn. (b) The aligned carbon nanotube forest is kept
stationary while the yarn is being drawn and twisted.
[0012] FIG. 3. SEM images of (a) a single ply (left), a double-ply
(middle), quandruple-ply (right) (b) a collection of single ply
carbon nanotube thread containing chemically linked carbon
nanotubes.
[0013] FIG. 4. A schematic drawing of the production of an aligned
carbon nanotube thin film by rolling. Left: A piece of carbon
nanotube forest impregnated with polyethylene glycol (PEG) is
sandwiched between two layers of paper; middle: Rolling is used to
press the carbon nanotube forest into a thin carbon nanotube film;
Right: The resulting carbon nanotube thin film is sandwiched
between two layers of paper. The paper was made from a mixture of
glass fibers and bi-component polymer fibers.
[0014] FIG. 5. SEM images of a carbon nanotube thin film. Left: low
magnification (50.times.). Right: high magnification
(3000.times.).
[0015] FIG. 6. A schematic showing carbon nanotube threads being
produced from aligned carbon nanotube ribbons.
[0016] FIG. 7. SEM images of two spools of carbon nanotube threads
made from aligned carbon nanotube ribbons. Left: single ply thread,
Right: a double ply thread.
[0017] FIG. 8. Two SEM images of a braided carbon nanotube
material.
[0018] FIG. 9. A schematic drawing of a piece of carbon nanotube
fabric.
[0019] FIG. 10. SEM images of carbon nanotube-based fabric made
from one ply threads (left) and two ply threads (right).
[0020] FIG. 11. Chemical reactions involved in the carbon nanotube
cross-linking through functionalization with
vinyl-triethoxysilane.
[0021] FIG. 12. Chemical reactions involved in the carbon nanotube
cross-linking through functionalization with
vinyl-triethoxyaminosilane.
[0022] FIG. 13. Chemical reactions involved in the carbon nanotube
functionalization with carboxyl groups followed by cross-linking
with a diamine.
[0023] FIG. 14. Chemical reactions involved in the carbon nanotube
carboxylation followed by thermal cross-linking.
[0024] FIG. 15. Stress-strain curves for CNT strips showing the
relative mechanical behavior of the three types of media.
DETAILED DESCRIPTION
Definitions
[0025] The term "carbon nanotubes" or "CNTs" are defined herein as
crystalline structures comprised of one or many closed concentric,
locally cylindrical, graphene layers. Their structure and many of
their properties are described in detail in Carbon Nanotubes:
Synthesis, Structure, Properties, and Applications, Topics in
Applied Physics. (Vol. 80. 2000, Springer-Verlag, M. S.
Dresselhaus, G. Dresselhaus, and P. Avouris, eds.) which is herein
incorporated by reference. Carbon nanotubes have demonstrated very
high mechanical strengths and stiffness (Collins and Avouris, 2000,
"Nanotubes for Electronics". Scientific American: 67, 68, and 69.)
They also have very high electrical conductivity which allow
current densities of more than 1,000 times that in metals (such as
silver and copper). These properties, including the high specific
strength and stiffness, will be beneficial to the materials
disclosed herein.
[0026] The term "yarn" is defined as a bundle of filaments
approximately spirally arranged to form a very-high aspect ratio,
approximately cylindrical structure. The filaments within the yarn
are substantially parallel, in a local sense, to neighboring
filaments.
[0027] The phrase "carbon nanotube yarn" is a yarn composed of a
plurality of carbon nanotubes.
[0028] The terms "thread" and "rope" are defined as high aspect
ratio, approximately cylindrical structures composed of more than
one strand of yarn. The term "rope" is defined as a high aspect
ratio approximately cylindrical structure composed of one yarn or
thread surrounded by additional carbon nanotubes forming the mantle
or outer sheath.
[0029] The present disclosure relates to high-strength, materials
comprising thread-like structures made from long carbon nanotubes
(CNTS) and the derived materials constructed from them. More
specifically, this invention relates to yarn, thread, rope, fabric
and composite materials employing long CNTs, bound and twisted.
[0030] Unlike the prior art, the materials of this disclosure
relates to carbon nanotube yarn containing (1) long or ultra-long
carbon nanotubes (>1 mm), that are (2) twisted about the
longitudinal axis of the yarn, and (3) chemically-linked together.
The benefit of combining these three characteristic is that they
allow the construction of ultra-light carbon nanotube based yarns
with significantly enhanced mechanical and/or electrical properties
over composite structures.
[0031] The present disclosure also describe carbon nanotube based
yarns, threads and ropes made from commercially available carbon
nanotubes with lengths in excess of 1 mm (FIG. 1), which are
spirally arranged about the longitudinal axis of the yarn and
chemically linked to adjacent neighboring carbon nanotubes.
[0032] In one embodiment, high quality, ultra-long, such as greater
than 1 mm, such as greater than 3 mm, or even greater than 1 cm,
such as greater than cm and small (<50 nm) diameter carbon
nanotubes are used, and the degree of helicity and chemical-linking
(described below) between the carbon nanotubes within the yarn is
optimized to achieve high performance. In addition, fabric
materials made by combining multiple strands of the disclosed yarn,
thread or rope are also considered part of this disclosure.
[0033] Covalent, ionic and metallic bond could be created between
adjacent carbon nanotubes to achieve chemical linkage and hence to
enhance the strength of yarn, thread, rope and fabric. As an
example, two carbon atoms from backbone of adjacent carbon
nanotubes can be bound together to create a covalent bond. Two
neighbor adjacent carbon nanotubes could also be chemically linked
by introducing moieties in between carbon nanotubes.
[0034] Molecules and their derivatives or substances containing
hydrogen, boron, carbon, nitrogen, oxygen, aluminum, silicon,
phosphorus, sulfur, titanium, vanadium, chromium, manganese, iron,
cobalt, nickel, copper, zinc, yttrium, zirconium, niobium,
molybdenum, ruthenium, rhodium, palladium, silver, cadmium, indium,
tin, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold,
lead, and bismuth could be employed for chemically linked the
adjacent carbon nanotubes via covalent, ionic and metallic
bonds.
[0035] In one embodiment, there may be attached to the carbon
nanotubes disclosed herein, at least one functional chemical group,
thereby forming a functionalized carbon nanotube. Non-limiting
examples of how such functionalized carbon nanotubes may be formed
are provided in U.S. Pat. Nos. 7,419,601 and 7,211,320, both of
which are herein incorporated by reference.
[0036] There are two methods for making yarns directly from aligned
carbon nanotube forest, and their schematic drawings showing these
generic methods are shown in FIG. 2. In the first method, the
carbon nanotube forest is spun while the yarn is drawn and the in
the second method the carbon nanotube forest is kept stationary
while the yarn is twisted while it is being drawn. Typically carbon
nanotubes with the morphology shown in FIG. 1 could be made into
yarns by this method.
[0037] The first method was used for producing carbon nanotube yarn
according to this disclosure. Once the preliminary yarn (called
singly ply thread) is made, the yarn can be spun into multiple-ply
thread. SEM images of single, double and quadruple-ply threads made
in Example 1 are shown in FIG. 3. As described in Example 1, these
threads were made from high quality carbon nanotubes and the
individual carbon nanotube measures 3 to 5 mm in length. The yarn
and thread shown in this disclosure incorporating the three new
features: long carbon nanotubes, twisted and chemically linked
together.
[0038] In Example 2, an alternative way of making carbon nanotube
yarns and threads are described. This is a two-step process, which
comprises: (1) making thin film of aligned carbon nanotubes and (2)
making yarn and thread out of the thin film.
[0039] A method of making thin film with aligned carbon nanotube by
rolling is shown in FIG. 4. In this embodiment, a piece of carbon
nanotube forest impregnated with polyethyleneglycol (PEG) is
initially sandwiched between two layers of paper; then a roller is
used to press the carbon nanotube forest into a thin carbon
nanotube film. Next, a carbon nanotube thin film will be formed
sandwiched between the two layers of paper. The paper used in this
process is a nonwoven paper made from a mixture of glass fibers and
bi-component polymer fibers.
[0040] The SEM images of the thin film made by the rolling
technique are shown in FIG. 5. Low magnification SEM image of
carbon nanotube ribbon shows that the total width of the ribbon of
.about.1.5 mm. High magnification SEM image shows carbon nanotubes
alignment within the film. Once the thin film is made, it can be
made into yarns and threads. A schematic drawing showing carbon
nanotube yarns being produced from aligned carbon nanotube ribbons
is shown in FIG. 6. Both a single ply and a double ply carbon
nanotube threads were made from the thin film shown in FIG. 6.
[0041] In one embodiment, the yarn can be made by twisting and
pulling the aligned carbon nanotube ribbons. SEM images of two
spools of carbon nanotube yarn and thread made from aligned carbon
nanotube ribbons is shown in FIG. 7.
[0042] A new type of yarn made from the blended material of above
disclosed carbon nanotube yarns and natural or synthetic fibers may
exhibit significantly different physical properties compared to
those of the original component yarns. This new blended yarn could
also be used in the making of other disclosed materials in this
invention for different applications.
[0043] Thread and rope may be made from the yarns disclosed above
primarily using two different techniques known as (1)
counter-spinning and (2) braiding. Chemical-linking of carbon
nanotubes between adjacent yarns may also be done after the threads
and ropes have been made in order to achieve a higher degree of
interaction between adjacent neighboring carbon-nanotubes
strands.
[0044] For the threads made by counter-spinning, some of the images
have been shown in FIG. 3 and FIG. 7. In addition, a braided
material (braided by three strands of double spun carbon nanotube
threads) was made by hand and SEM images of it are shown in FIG.
8.
[0045] High strength fabrics may also be constructed from the above
mentioned yarns, threads or ropes. These fabrics can be either
woven or nonwoven. Chemical-linking of carbon nanotubes may also be
done after fabrics are made in order to achieve a higher degree of
mechanical attachment between adjacent neighboring yarns, threads
or ropes to enhance the strength of the material.
[0046] Schematic drawings and SEM images showing the structure of
the carbon nanotube fabric made by weaving yarn and thread together
are shown in FIG. 9, and FIG. 10, respectively. The woven fabric in
FIG. 10 was made by hand with a loom and a mixture of single ply
and double ply thread was used. The diameter of the threads in the
fabric is in the range of 20 to 50 um.
[0047] Composite materials can also be made from the above
mentioned yarns, threads, ropes and fabrics with the incorporation
of other constituent materials. The constituent materials could be
chosen from metals, natural and synthetic polymeric materials,
ceramic materials and their combinations. There are many methods of
making composites from these materials including: (1) impregnation
of the carbon nanotubes with organic and/or inorganic molecules in
solution; (2) dipping the materials into solutions or suspensions
of organic and inorganic molecules followed by the evaporation of
the solvent; (3) coating or filling the carbon nanotubes with
metals, organic or other inorganic compounds in a gas phase
technique.
[0048] Chemical-linking between carbon nanotubes and other
constituent materials could also be achieved via covalent bond,
ionic bond and metallic bond. These could further improve
performance by increasing the interaction between various
components.
[0049] The non-limiting examples of polymeric materials are chosen
from single or multiple component polymers including nylon,
polyurethane, acrylic, methacrylic, polycarbonate, epoxy, silicone
rubbers, natural rubbers, synthetic rubbers, vulcanized rubbers,
polystyrene, polyethylene terephthalate, polybutylene
terephthalate, Nomex (poly-paraphylene terephtalamide), Kevlar poly
(p-phenylene terephtalamide), PEEK (polyester ester ketene), Mylar
(polyethylene terephthalate), viton (viton fluoroelastomer),
polyetrafluoroethylene, polyetrafluoroethylene), halogenated
polymers, such as polyvinylchloride (PVC), polyester (polyethylene
terepthalate), polypropylene, polychloroprene, and multi-component
polymers, and combination thereof.
[0050] The non-limiting examples of metallic and ceramic materials
that can be used in the composite materials described herein are
chosen from boron carbide, boron nitride, boron oxide, boron
phosphate, spinel, garnet, lanthanum fluoride, calcium fluoride,
silicon carbide, carbon and its allotropes, silicon oxide, glass,
quartz, aluminum oxide, aluminum nitride, zirconium oxide,
zirconium carbide, zirconium boride, zirconium nitrite, hafnium
boride, thorium oxide, yttrium oxide, magnesium oxide, phosphorus
oxide, cordierite, mullite, silicon nitride, ferrite, sapphire,
steatite, titanium carbide, titanium nitride, titanium boride,
molybdenum, nickel, silver, zirconium, yttrium, and alloys or
combination thereof.
[0051] One of the carbon nanotube cross-linking approaches
described herein could utilize silane chemistry. In this
embodiment, the process could be described as: (1) attachment of
vinyltrialkoxysilanes to carbon nanotube sidewall via a free
radical reaction; (2) hydrolysis of the trialkoxysilane moiety; and
(3) thermal process between 120-150.degree. C. The hydroxysilane
groups will form siloxane --Si--O--Si-- bridges between the outer
shells of adjacent nanotubes after this process (FIG. 11).
[0052] A similar process using amino groups for cross-linking
carbon nanotubes is shown in FIG. 12. It is known that in acidic
water solutions amines exist in protonated, that is positively
charged form. Such property of amino groups grafted to nanotubes
could assist in building up positive surface charge. The
functionalization and cross-linking steps are shown in FIG. 12.
[0053] Another approach for cross-linking of carbon nanotubes is
shown in FIG. 13. The process could be described as: (1)
Oxidization of carbon nanotubes in order to render their surface
negatively charged due to the carboxyl groups. (2) Linkage between
the carboxyl groups attached to the adjacent nanotubes via a
diamine. Similar cross-linking could also be achieved by the
reaction between a carboxyl group and an amino group resulting in
the formation of amide moiety (also shown in FIG. 13).
[0054] Other than the techniques mentioned above, post treatment of
the disclosed materials could be achieved via high temperature
thermal annealing, passing high electric current through the
disclosed materials, electron beam and/or ion radiation (chemical
reactions involved in these process are shown in FIG. 14). Further
improvement of the thermal annealing method could be attempted by
introducing additional source of carbon into the thread prior the
annealing.
[0055] Two of the above mentioned cross-linking approaches were
employed in Example 5 and mechanical testing results from three
types of materials are shown in FIG. 15. Clearly, mechanical
performance of the materials could be enhanced as expected by the
used chemical-linking approaches between carbon nanotubes.
[0056] The above mentioned yarns, threads or ropes made with carbon
nanotubes having differing characteristics can be woven together to
create unique materials that take advantage of the incredibly
diverse properties of the carbon nanotube. For example, depending
on the application, carbon nanotubes that exhibit unique
electrical, thermal, electromagnetic, strength, and
filtration/detection properties can be combined in a yarn to be
woven into a multifunctional material.
[0057] The invention will be further clarified by the following
non-limiting examples, which is intended to be purely exemplary of
the invention.
EXAMPLES
Example 1
Carbon Nanotube Yarn and Thread from Dry Process
[0058] Raw carbon nanotubes were provided by NanoTech Labs
(Yadkinville, N.C. 27055) in clusters typically measuring 3 to 5 mm
thickness, 1-2 cm long and 1-2 cm wide. They were used for carbon
nanotube yarns making with individual carbon nanotube measuring 3-5
mm in length. Yarns according to this example were made by: a)
continuously and sequentially pulling carbon nanotubes from the
as-received carbon nanotube clusters; b) twisting the carbon
nanotube fibers to make the yarn; c) winding the resulting yarn on
to the collecting spool; d) carboxyl functionalization of the spool
of yarn; e) heat treating at 500.degree. C. for 30 min to achieve
cross-linking within the yarn. The twisting and collection was
performed automatically to achieve uniformity.
[0059] The yarns shown in FIG. 3 were made by using the first
method (shown in FIG. 2), which comprised spinning the carbon
nanotube forest while the yarn was drawn. By using counter-spinning
technique, the yarn (also called singly ply thread) could be spun
into multiple-ply thread. SEM images of single, double and
quadruple-ply threads are shown in FIG. 3. These threads were made
from high quality carbon nanotubes and the individual carbon
nanotube measures 3 to 5 mm in length. The yarn and thread shown in
this disclosure incorporating the three new features: long carbon
nanotubes, twisted and chemically linked together.
Example 2
Wet Spun Carbon Nanotube Yarns
[0060] The carbon nanotube yarns according to this example were
produced by: a) impregnating carbon nanotube material with
PEG-2000; b) removing the excess PEG from the carbon nanotube
material to make carbon nanotube dough; c) sandwiching the
resulting carbon nanotube dough between two layers of paper; d)
producing thin film by repeatedly running roller over the carbon
nanotube dough; e) slitting the carbon nanotube thin film into
narrow ribbons; f) twisting the narrow ribbons into yarns; g)
baking the resulting yarns at 220.degree. C. for half an hour; h)
carboxylation of the spool of yarn; i) heating at 500.degree. C.
for 30 mins to achieve cross-linking within the yarn.
[0061] The method for making carbon nanotube thin film is depicted
in FIG. 4 and the SEM images of the resulted thin film are shown in
FIG. 5. Low magnification SEM image of carbon nanotube ribbon shows
a total width of the ribbon of .about.1.5 mm. High magnification
SEM image is showing carbon nanotubes alignment within the
film.
[0062] The method for making carbon nanotube yarns from aligned
carbon nanotube ribbons is depicted in FIG. 7. SEM images of two
spools of carbon nanotube yarn and thread made from the above
aligned carbon nanotube ribbons are shown in FIG. 8. These yarn and
thread were made by twisting and pulling the aligned carbon
nanotube ribbons and both a single ply and a double ply carbon
nanotube yarn and thread were made from the thin film shown in FIG.
6.
Example 3
Braided Carbon Nanotube Materials
[0063] By using the techniques shown in example 1, some double ply
threads were made. Using the conventional technique, under optical
microscope, a piece of braided material was made by tweezers. Two
SEM images of a braided carbon nanotube material are shown in FIG.
8 and three strands of double spun carbon nanotube yarns were used
in this braided material.
Example 4
Carbon Nanotube Fabric
[0064] By using the techniques shown in example 1, some single ply
and double ply threads were made. A schematic drawing of a piece of
carbon nanotube fabric is shown in FIG. 9. Under optical
microscope, a home made loom was used for the weaving of the
fabric. SEM images of the piece of woven fabric are shown in FIG.
10. The fabric was woven from a mixture of single and double spun
carbon nanotube yarns. The diameter of the yarns is in the range of
20 to 50 um.
Example 5
Chemical-Linking of Carbon Nanotubes
[0065] The experiments on cross-linking of carbon nanotubes were
performed over carbon nanotube strips. The same process could be
applied to the disclosed materials in this invention.
[0066] Long CNTs (3-5 mm in length) with diameters of 30-50 nm
provided by NanoTechLabs were used as received. The detail
procedure of the experiments is described as:
[0067] I. Thermal Annealing
[0068] (1) Long CNTs were acid washed and dispersed.
[0069] (2) Suspension of carbon nanotubes were deposited onto
carbon cloth substrate discs.
[0070] (3) Carbon nanotube membrane was peeled off the substrate,
pressed with a hand roller and dried.
[0071] (4) Seven thin strips of roughly 0.25 mm thickness were slit
from the central part of each membrane. These strips were called
untreated.
[0072] (5) Four of the seven strips were annealed at 500.degree. C.
for half an hour. These strips were called heat treated.
[0073] II. Chemical Treatment
[0074] (1) Vinyltrialkoxysilanes were attached to the long carbon
nanotube sidewall via free radical reaction.
[0075] (2) Functionalized carbon nanotubes from step 1 were
dispersed.
[0076] (3) Suspension of carbon nanotubes were deposited onto
carbon cloth substrate discs.
[0077] (4) Carbon nanotube membrane was peeled off the substrate,
pressed with a hand roller and dried.
[0078] (5) Carbon nanotube membrane was thermal processed at
120-150.degree. C. to form siloxane --Si--O--Si-- bridges between
the outer shells of the adjacent nanotubes.
[0079] All 10 strips were tested with an MTS Insight Tensile Tester
under uniaxial tensile loading and the stress-strain curves for
each strip are shown in FIG. 15. The early mechanical behavior of
both types of cross-linked strips is very similar (nearly equal
slope) with the chemically linked strips being able to withstand
higher applied stresses. Both types of treated strips were shown to
consistently carry a higher tensile loading before breaking and
have a steeper stress-strain relationship, conclusively
demonstrating an improvement in the mechanical behavior in tensile
strength.
[0080] Unless otherwise indicated, all numbers expressing
quantities of ingredients, reaction conditions, and so forth used
in the specification and claims are to be understood as being
modified in all instances by the term "about." Accordingly, unless
indicated to the contrary, the numerical parameters set forth in
the following specification and attached claims are approximations
that may vary depending upon the desired properties sought to be
obtained by the present invention. It is intended that the
specification and examples be considered as exemplary only, with
the true scope of the invention being indicated by the following
claims.
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