U.S. patent application number 15/360265 was filed with the patent office on 2018-05-24 for nontoxic and non-incendiary obscurant compositions and method of using same.
The applicant listed for this patent is John L. Lombardi. Invention is credited to John L. Lombardi.
Application Number | 20180141880 15/360265 |
Document ID | / |
Family ID | 62144285 |
Filed Date | 2018-05-24 |
United States Patent
Application |
20180141880 |
Kind Code |
A1 |
Lombardi; John L. |
May 24, 2018 |
Nontoxic and Non-incendiary Obscurant Compositions and Method of
Using Same
Abstract
White smoke formulations comprising triazine-borate cage
compounds or triazine-phosphate cage compounds obscurants and a
sucrose-potassium chlorate pyrotechnic fuel-oxidizer system are
disclosed.
Inventors: |
Lombardi; John L.; (Tuscon,
AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lombardi; John L. |
Tuscon |
AZ |
US |
|
|
Family ID: |
62144285 |
Appl. No.: |
15/360265 |
Filed: |
November 23, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C06B 29/08 20130101;
C06D 3/00 20130101 |
International
Class: |
C06B 29/08 20060101
C06B029/08 |
Claims
1. A composition to produce smoke upon combustion, comprising a
triazine, wherein said triazine has obscurant characteristics.
2. The composition of claim 1, wherein further comprising a second
obscurant.
3. The composition of claim 1, wherein said triazine is selected
from a group consisting of melamine, N-acylated melamine,
N-arylated melamine, N-alkylated melamine, acetoguanamine,
N-acylated acetoguanamine, N-arylated acetoguanamine, N-alkylated
acetoguanamine, benzoguanamine, N-acylated benzoguanamine,
N-arylated benzoguanamine, N-alkylated benzoguanamine, and any
combinations thereof.
4. The composition of claim 2, wherein said second obscurant is
selected from a group consisting of triethanolamine borate,
triethanolamine phosphate, pentaerythritol borate, pentaerythritol
phosphate alcohol, pentaerythritol phosphate alcohol carboxylate,
silicate esters, and any combinations thereof.
5. The composition of claim 4, wherein said second obscurant is
triethanolamine borate.
6. The composition of claim 1, further comprising a propellant,
wherein the propellant comprises an oxidizer and a fuel.
7. The composition of claim 6, wherein said oxidizer is selected
from a group consisting of alkali, alkaline earth chlorate,
potassium chlorate, sodium chlorate, and any combinations
thereof.
8. The composition of claim 7, wherein said oxidizer is potassium
chlorate.
9. The composition of claim 6, wherein said fuel is one or more
carbohydrates.
10. The composition of claim 9, wherein said fuel is sucrose.
11. The composition of claim 1, wherein said smoke produced by
combustion of the composition has a low peak combustion
temperature.
12. The composition of claim 11, wherein said low peak combustion
temperature is lower than 350.degree. C.
13. The composition of claim 1, wherein said smoke produced by
combustion of the composition has a high obstruction property,
wherein said high obscuration property is greater than 200%
transmittance.
14. The composition of claim 1, wherein said smoke produced by
combustion of the composition has a gradient burn rate
characteristic, wherein the produced smoke lasts longer and
denser.
15. The composition of claim 1, wherein further comprising a burn
rate retarder.
16. The composition of claim 15, wherein said burn rate retarder is
selected from the group consisting of oxamide, biuret, and
derivatives thereof.
17. The composition of claim 16, where said burn rate retarder
causes over about 40% reduction in burn rate.
18. The composition of claim 1, wherein further comprising a burn
rate accelerant.
19. The composition of claim 18, wherein said burn rate accelerant
is selected from the group consisting of manganese dioxide
(MnO.sub.2), cobalt oxide (Co.sub.3O.sub.4), iron oxide
(Fe.sub.2O.sub.3), manganese chloride tetrahydrate
(MnCl.sub.2-4H.sub.2O), cobalt chloride hexahydrate
(CoCl.sub.2-6H.sub.2O), and iron chloride hexahydrate
(FeCl.sub.3-6H2O).
20. The composition of claim 19, wherein said burn rate accelerant
is MnO.sub.2 and causes over about 20% increase in burn rate.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a composition that produces a
non-toxic, non-incendiary, and highly obscuring cloud of smoke upon
combustion and a method of making obscurant devices based on said
composition.
BACKGROUND OF THE INVENTION
[0002] A burgeoning need exists for efficient, nontoxic highly
obscuring smoke, which is produced at relatively low combustion
temperatures. Current conventional smoke formulations, for
examples, hexachloroethane (HC) smokes and red phosphorus (RP)
smokes, have high burn temperatures, which pose a dangerous and
undesirable secondary fire risk to structures and personnel
especially within high density urban warfare environments.
SUMMARY OF THE INVENTION
[0003] Certain embodiments of Applicant's disclosure disclose white
smoke formulations comprising triazine-borate cage compounds or
triazine-phosphate cage compounds obscurants and a
sucrose-potassium chlorate pyrotechnic fuel-oxidizer system.
[0004] Applicant's white smoke formulations exhibit low peak
combustion temperatures, high visual obstruction properties, and
gradient burn characteristics.
[0005] Further, when a burn rate modifier, either a burn rate
accelerant or a burn rate retarder, is added to the white smoke
formulations, a difference greater than 40% in burn rate is
observed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The invention will be better understood from a reading of
the following detailed description taken in conjunction with the
drawings in which like reference designators are used to designate
like elements, and in which:
[0007] FIG. 1 illustrates transmittance percentages of RP smoke and
the melamine/acetoguanamine triazine borate (MATEAB) white smoke
formulation;
[0008] FIG. 2 illustrates different embodiments of smoking devices
with gradient burn characteristics;
[0009] FIG. 3A shows mass extinction coefficient values of the
METEAB white smoke formulation with Chlorez polychlorinated wax
latent HCL additive is tested under about 80% ambient humidity;
[0010] FIG. 3B illustrates the mass extinction coefficient values
of the MATEAB white smoke formulation with sucralose latent HCl
additive is tested under about 80% ambient humidity;
[0011] FIG. 3C shows the mass extinction coefficient values of the
MATEAB white smoke formulation with PEPA latent phosphoric acid
additive is tested under about 20% ambient humidity;
[0012] FIG. 3D illustrates the mass extinction coefficient values
of the MATEAB white smoke formulation with PEPA latent phosphoric
acid additive is tested under about 80% ambient humidity;
[0013] FIG. 4 shows that the MATEAB white smoke formulation has a
higher mass extinction coefficient value a (m.sup.2/g) at visible
light spectral wavelengths most sensitive to the photopic cone (550
nm) and scotopic rod cells (500 nm) responsible for human eye
vision compared to TA and RP smoke formulations.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] This invention is described in preferred embodiments in the
following description with reference to the Figures, in which like
numbers represent the same or similar elements. Reference
throughout this specification to "one embodiment," "an embodiment,"
or similar language means that a particular feature, structure, or
characteristic described in connection with the embodiment is
included in at least one embodiment of the present invention. Thus,
appearances of the phrases "in one embodiment," "in an embodiment,"
and similar language throughout this specification may, but do not
necessarily, all refer to the same embodiment.
[0015] The described features, structures, or characteristics of
the invention may be combined in any suitable manner in one or more
embodiments. In the following description, numerous specific
details are recited to provide a thorough understanding of
embodiments of the invention. One skilled in the relevant art will
recognize, however, that the invention may be practiced without one
or more of the specific details, or with other methods, components,
materials, and so forth. In other instances, well-known structures,
materials, or operations are not shown or described in detail to
avoid obscuring aspects of the invention.
[0016] Applicant's disclosure addresses these issues by developing
formulations that produce low toxicity and highly visually
obscuring white smoke at low combustion temperature (Peak Exotherm
Temperature <400.degree. C.). These formulations also exhibit a
gradient burn rate characteristic, which initially rapidly release
smoke accompanied by gradual slowing of smoke production rate. This
characteristic enables both rapid dispersal and maintenance of a
higher density smoke screen that can be achieved via conventional
and more linear burn rate smoke munitions.
[0017] Applicant's disclosure benefits in terms of both enhanced
military capability coupled with cost reduction. Such benefits are
described in greater details below.
[0018] In certain embodiments, given the smoke formulations' low
peak combustion temperature coupled with gradient burn
characteristics, the smoke formulations offer enhanced military
capabilities particularly in high density urban conflict
environments where secondary fire risk towards personnel and
structures is of concern. Gradient burn rate characteristics are
advantageous since this enables rapid, initial smoke screen
establishment accompanied by its maintenance and persistence for
time durations longer than conventional smoke munitions. Persistent
smoke screens are desirable because they offer greater and longer
protection towards personnel and hardware.
[0019] The Applicant's smoke formulations are compatible with the
current smoke manufacturing paradigm and are formulated from
inexpensive, readily commercially available components which do not
have restrictive transportation and handling and storage
requirements associated with HC, RP, or white phosphorus (WP)
smokes. The instant smoke compositions not only demonstrate
low-toxicity and enhanced obscuration properties, but also are more
cost effective than other existing candidates. A series of highly
obscuring pyrotechnic smoke formulations comprising triazine-borate
or phosphate cage compound obscurants blended with conventional
sucrose-potassium chlorate pyrotechnic propellant have been
developed. Triazines comprise six membered carbon-nitrogen
heterocyclic compounds including melamine, acetoguanamine,
benzoguanamine and their N-acylated (i.e. N-Acetyl Melamines,
N-Trihalooacetyl Melamines), N-Arylated and/or N-Alkylated
derivatives. In other embodiments, the triazines can be in partial
or completely neutralized salt form. In yet other embodiments, the
triazines can be as free base. In certain embodiments borate and
phosphate cage compounds comprise trialkanolamine derived borate or
phosphate compounds including but not limited to triethanolamine
borate, triisopropanolamine borate, pentaerythritol borate (free
acid or its ammonium, alkyl ammonium, aryl ammonium, pyridinium,
anilinium, triazinium, or guanidinium salts) triethanolamine
phosphate, pentaerythritol phosphate alcohol (PEPA) and PEPA
carboxylate or silicate esters.
[0020] In certain embodiments, Applicant's smoke formulations not
only contain new obscurant chemicals, but also that their
combustion characteristics, such as, burn rate or peak exotherm
combustion temperature, can be customized and controlled by adding
minor amounts of burn rate modifiers (accelerants or
retardants).
[0021] Applicant has developed smoke formulations suitable for 155
mm smoke canister munitions having lower peak combustion
temperatures (T<400.degree. C.), higher obscuration properties
(>200%), relative to conventional TA smoke, and gradient burn
rate characteristics (customizable longer and denser smoke
production) relative to corresponding conventional nontoxic and
non-incendiary 37 mm smoke canister, AN-M8 smoke grenade, AN-M83
smoke grenade, and/or 155 mm (e.g. short M116A1 or long M825A1)
smoke munitions. "About" described herein is used to capture any
internal measure errors.
[0022] Further, Applicant has found that small amounts (<5 wgt.
%) of burn rate modifiers can be separately and successfully
formulated into Applicant's white smoke composition. In certain
embodiments, an accelerant is selected from the group consisting of
manganese dioxide (MnO.sub.2), cobalt oxide (Co.sub.3O.sub.4), iron
oxide (Fe.sub.2O.sub.3), manganese chloride tetrahydrate
(MnCl.sub.2-4H.sub.2O), cobalt chloride hexahydrate
(CoCl.sub.2-6H.sub.2O), iron chloride hexahydrate
(FeCl.sub.3-6H2O), and any combinations thereof. In other
embodiments, an accelerant comprise a high surface area
heterogeneous combustion catalyst, such as high surface area
carbon, metal, metal carbide, metal oxide and the like. Further, a
retarder is selected from the group consisting of oxamide, biuret,
nitroguanidine, urea, calcium carbonate, calcium sulphate, ammonium
chloride, ammonium sulphate, dicyanoguanidine, chlorinated
hydrocarbons, aluminum hydroxide, ammonium salts (sulphate,
oxalate, phosphate), lithium fluoride, strontium carbonate,
N-bromosuccinimide, hexabromocyclododecane, pentabromodiphenyl
oxide, decabromodiphenyl oxide, tetrabromophthalatediol,
tetrabromophthalic anhydride, triphenyl antimony, diammonium
bitetrazole, 5-aminotetrazole, ammonium polyphosphate, and any
combinations thereof.
[0023] Applicant has found that the modified MATEAB white smoke
formulations, i.e., small amount of burn rate modifiers are added
to said formulations, exhibit >.+-.20% burn rate difference
between unmodified MATEAB control white smoke, i.e., small amount
of burn rate modifiers are not added to said formulations.
[0024] Moreover, Applicant has found that pellets can be pressed
with modified MATEAB white smoke formulations and that the modified
MATEAB white smoke formulation pellets exhibit low peak combustion
temperatures (T<400.degree. C.) and higher obscuration
properties (>200%) relative to conventional nontoxic and
non-incendiary smoke. Furthermore, the modified MATEAB white smoke
formulation pellets can be loaded into subscale devices, such as 37
mm, M8, M83 grenades, 155 mm smoke projectiles, etc.
[0025] In addition, gradient burning characteristics are imparted
to representative above listed devices by varying burn rate
modified pellets either axially (end burning pellet configuration)
or radially (core burning pellet configuration). Adding minor
amounts of burn rate accelerants or retardants enable more
efficient and prolonged smoke screen generation than smoke screen
generation achieved through conventional smoke devices. The
representative above devices charged with modified MATEAB white
smoke formulations have low peak combustion temperatures
(T<400.degree. C.) and higher obscuration properties (>200%)
relative to conventional nontoxic and non-incendiary smoke.
Further, the modified MATEAB white smoke formulations can be
successfully scaled up into a bulk production, i.e., approximately
>10 Kg/day process.
[0026] In certain embodiments, Applicant's smoke devices are
prepared to have smoke charges containing desired burn rate
modifier composition gradients which vary either radially (gradient
core burning configuration) or axially (gradient end burning
configuration). Referring to FIG.2, a smoking device 200 comprises
a pyrotechnic charge 202, which is disposed throughout all
pyrotechnic pellets 204a-e. In a different embodiment of a smoking
device 300, the pyrotechnic charge 302 has a reversed conical
shape. Both smoking device 200 and smoking device 300 are
non-limiting examples of gradient core burning configuration. In
other embodiments, each pellet can have a different size of a
pyrotechnic charge. The different surface area contacting a
pyrotechnic charge within a pyrotechnic pellet contributes to a
different burn rate thereof.
[0027] Inclusion of a burn rate retarder or accelerant introduces a
composition gradient into the charge and thereby effecting charge
combustion and the amount of smoke produced at various time
intervals by a device. In certain embodiments, each pyrotechnic
pellet comprises either a retardant or an accelerant. Pyrotechnic
pellets 204a-e can all have the same weight percentage of a
retardant or an accelerant. In other embodiments, pyrotechnic
pellets 204a-e can each has a different weight percentage of a
retardant or an accelerant, therefore, the smoking device 200
comprises a composition gradient which effect the combustion front
burn rate and amount of smoke emitted at various pre-determined
locations along the pyrotechnic charge 202. Similarly, the
pyrotechnic pellets 304a-e can each has a different weight
percentage of a retardant or an accelerant, therefore, the smoking
device 300 comprises a composition gradient which effects the
combustion front burn rate and amount of smoke emitted at various
pre-determined locations along the pyrotechnic charge 302.
[0028] In certain embodiments, a smoking device 400 illustrates a
non-limiting example of gradient end burning configuration. The
smoke device 400 comprises a pyrotechnic charger 402, a plurality
of pyrotechnic pellets 404a-e, and an exit orifice 406. In certain
embodiments, Burn retardant concentration within fast, initial end
burning devices would vary directly with distance to device orifice
whereas slow initial end burning devices would possess higher
retardant concentrations within close proximity to the device
orifice. In some embodiments, a burn rate retardant comprises a
chemical compound which inhibits pyrotechnic charge burn rate (e.g.
oxamide, biuret or related derivatives). In other embodiments, a
burn rate retardant comprises an inert filler which merely
decreases active pyrotechnic charge areal concentration.
[0029] In certain embodiments, one could also produce a fast end
burning device via introducing high concentrations of burn rate
accelerant in the pyrotechnic pellets at close distances to the
exit orifice accompanied by a tapering off and/or inclusion of
retardant at distances further away from the exit orifice.
[0030] The following examples are presented to further illustrate
to persons skilled in the art how to make and use the invention.
These examples are not intended to be limiting.
EXAMPLE 1
Synthesis of OCC Obscurants
[0031] In certain embodiments, OCC obscurants are synthesized
because unlike their parent acids, OCC compounds have cyclic
structures allowing ready sublimation at low temperatures as
evidenced by their reasonably low heat of vaporization
thermodynamic properties. OCC compounds comprising non-toxic
pentaerythritol phosphate alcohol (PEPA) 3, esterified derivatives
thereof, triethanolamine borate (TEAB) 6, are formed according to
the following equations:
##STR00001##
[0032] In certain embodiments, OCC compounds comprises
pentaerythritol borate 8, having a structure of
##STR00002##
[0033] and/or triethanolamine phosphate (TEAP) 7, having a
structure of
##STR00003##
[0034] TEAB 6 can be efficiently sublimed at low temperatures
(T<250.degree. C.) using conventional sucrose-chlorate
pyrotechnic composition. Upon combination with atmospheric
moisture, TEAB 6, PEPA 3, pentaerythritol borate, and TEAP 7
decompose to nontoxic highly obscuring hydrated polyboric or
polyphosphoric acid aerosol smoke particles. In certain
embodiments, these acids readily form stable, strongly hydrogen
bonded salt aerosol smoke particles with co-sublimed alkaline
melamine and acetoguanamine obscurants. Further, MATEAB white smoke
aerosol particles are efficient at scattering visible light.
Further, the triazine borates and phosphates show low acute
toxicity.
[0035] A variety of synthetic strategies and precursor compounds
are evaluated including via direct esterification and
transesterification routes to determine the optimal means for
efficient TEAB 6 and TEAP 7 production.
[0036] Table 1 summarizes the properties of several obscurant
compounds.
TABLE-US-00001 TABLE 1 Total Number of Hydrogen Density
.DELTA.H.sub.vap Bonding Compound Structure .delta.
(cal.sup.1/2ml.sup.-1/2).sup.a (g/mL).sup.b (cal/g) Sites.sup.b
Terephthalic Acid (TA) ##STR00004## 12.0 1.51 99 6 Melamine
##STR00005## 16.0 1.66 155 12 Acetoguanamine ##STR00006## 13.7 1.39
135 9 Triethanolamine Borate (TEAB) ##STR00007## 8.15 1.13 58.8 4
Pentaerythritol Phosphate Alcohol (PEPA) ##STR00008## 10.3 1.35
78.4 6 .sup.a.delta. values calculated from Van Krevelen, D. W.
Properties of Polymers, 3.sup.rd ed.; Elsevier: New York,
1997..sup.4 .sup.bDensity values and H-bonding sites calculated
using ACD/Labs Software V 11.01 on CAS SciFinder Scholar.
EXAMPLE 2
[0037] Mixtures between TEAB 6 and similar structured PEPA 3 cage
compound obscurants within conventional sucrose-chlorate
pyrotechnic propellant are prepared and evaluated (see Tables I
& II below for representative MATEAB white smoke and
MATEAB-PEPA white smoke producing pyrotechnic formulations.)
Blending was accomplished within acetone vehicle followed by mixing
via a Kitchen Aid Planetary Mixer. The resultant powder blend was
subsequently dried within an air convection oven at 40.degree. C.
followed by compaction into candidate one inch diameter pyrotechnic
pellets via a Caver Hydraulic Press operating at 5000 lb dead load
for 10 second duration. An acetone slurry of 511 igniter
composition was applied and dried atop of each pellet followed by
ignition using a nichrome resistance wire heater (see Table V below
for 511 igniter composition employed).
TABLE-US-00002 TABLE II MATEAB Pyrotechnic White Smoke Formulation
(1) Component Weight % Potassium Chlorate Oxidizer 33.75 Sucrose
Fuel 13.31 Melamine Obscurant 21.86 TEAB Obscurant 16.75
Acetoguanamine Obscurant 14.33
TABLE-US-00003 TABLE III MATEAB Pyrotechnic White Smoke Formulation
(2) Component Amount (g) Weight % Potassium Chlorate Oxidizer 33.75
33.70% Sucrose Fuel 13.40 13.38% Melamine Obscurant 21.87 21.84%
TEAB Obscurant 16.78 16.75% Acetoguanamine Obscurant 14.36
14.34%
TABLE-US-00004 TABLE IV MATAEB - PEPA Pyrotechnic White Smoke
Formulation Concentration Component (Weight %) Potassium Chlorate
32.14 Sucrose 12.68 Melamine 20.82 TEAB 15.95 Acetoguanamine 13.64
PEPA 4.77
TABLE-US-00005 TABLE V 511 Igniter Composition Employed to Ignite
MATEAB & MATEAB PEPA Pyrotechnic White Smoke Producing
Formulations Concentration Component (Weight %) Silicon Metal (325
Mesh) 26.0 Potassium Nitrate 35.0 Iron (II) Oxide, Black 22.0
German Blackhead Aluminum Powder 13.0 Charcoal Powder 4.0
[0038] In certain embodiments, other latent HCL source, other than
sucrose, can be used in MATEAB and/or MATEAB PEPA Pyrotechnic White
Smoke Producing formulations. The latent HCl source comprises
sucralose having a structure of
##STR00009##
[0039] and/or Chlorez chlorinated wax having a structure of
##STR00010##
[0040] Referring to FIG. 3A, the mass extinction coefficient values
of the MATEAB white smoke formulation with Chlorez wax latent HCl
additive is tested under about 80% ambient humidity.
[0041] Referring to FIG. 3B, the mass extinction coefficient values
of the MATEAB white smoke formulation with sucralose latent HCl
additive is tested under about 80% ambient humidity.
[0042] Referring to FIG. 3C, the mass extinction coefficient values
of the MATEAB white smoke formulation with PEPA latent phosphoric
acid additive is tested under about 20% ambient humidity.
[0043] Referring to FIG. 3D, the mass extinction coefficient values
of the MATEAB white smoke formulation with PEPA latent phosphoric
acid additive is tested under about 80% ambient humidity.
[0044] Table VI summarizes the mass extinction coefficient values
of the MATEAB white smoke formulation, the MATEAB white smoke
formulation with Chlorez wax latent HCl additive, the MATEAB white
smoke formulation with sucralose latent HCl additive, and the
MATEAB white smoke formulation with PEPA latent phosphoric acid
additive.
TABLE-US-00006 EC400 EC500 EC600 Relative Formulation (M{circumflex
over ( )}2/g) (M{circumflex over ( )}2/g) (M{circumflex over (
)}2/g) Humidity MATEAB 0.58 1.74 1.87 20% MATEAB 1.64 1.1 2.33 80%
MATEAB + 2.5 0.89 1.7 1.93 20% mol % sucralose replacement MATEAB +
2.5 0.80 1.86 2.18 80% mol % sucralose replacement MATEAB + 5 0.97
1.7 1.57 20% mol % sucralose replacement MATEAB + 5 0.42 0.56 2.14
80% mol % sucralose replacement MATEAB + 10 0.37 2.4 1.44 20% mol %
sucralose replacement MATEAB + 10 0.37 0.88 1.81 80% mol %
sucralose replacement MATEAB + 3% 0.35 1.01 0.78 20 by wt Chlorez +
0.5% by wt nitrocellulose + 1% by wt SMA EF60 MATEAB + 3% 0.10 1.62
1.90 80 by wt Chlorez + 0.5% by wt nitrocellulose + 1% by wt SMA
EF60
[0045] In certain embodiments, the obscurants are finely ground and
Roto-Tap screened followed by blending with measured amounts of
confectionary grade sucrose sugar fuel and potassium chlorate
oxidizer. Various amounts of obscurant and sucrose-chlorate
propellant are mixed within acetone solvent using an overhead
Hobart Mixer followed by careful drying. The resulting dried
obscurant and propellant powder mixtures are separately reground,
Roto-Tap screened, and pressed into candidate smoke testing pellets
using a hydraulic Carver Press within a cylindrical steel mold
(about 6,000 lbs compaction load/15 second load duration).
[0046] Representative pellets are then separately combusted and the
resulting smoke obscuring properties are characterized as a
function of incandescent interrogation light wavelength at various
ambient humidity levels using a smoke box outfitted with a Thorlabs
CCS200 Compact Fiber Visible/Near Infrared (NIR) Spectrometer
(500-1000 nm spectral sensing wavelength range, with 4 nm
resolution). A mixing fan is incorporated into the smokebox to
ensure the smoke is uniformly homogenized within the 0.112 m.sup.3
chamber volume. Pellet ignition is accomplished using an
electrically resistive Nichrome wire igniter situated atop the
pellet surface. An incandescent lamp, which is used to interrogate
the pellet combustion smoke, is set to 6 Volts and the path length
to a. Comparative testing is conducted in smoke box for OCC versus
conventional sized TA pellet formulations.
[0047] In certain embodiments, the pellet combustion trials within
the smoke box entails smoke formulations comprising compounds
mixtures between triazines and TEAB 6 or triazines and TEAP 7. The
baseline obscuring properties of the MATEAB smoke formulations
without burn rate modifiers are established first. Then pellets
comprising MATEAB smoke formulations are reformulated with burn
rate modifiers and modified obscuring properties are evaluated.
[0048] Table VII and Table VIII summarize the properties of several
chlorate oxidizers and metal oxides.
TABLE-US-00007 TABLE VII (Smoke Formulation Pyrotechnic Propellant
Decomposition Catalysts & Reported Chlorate Oxidizer Half Mass
Decomposition Temperatures) 50% Chlorate Metal Cation d
Decomposition Shell Electronic Melting Point Temperature Catalyst
Configuration .sup.1 (.degree. C.) (.degree. C.) .sup.1
CoCl.sub.2--6H.sub.2O d.sup.7 86 317 FeCl.sub.3 6H.sub.2O d.sup.5
37 340 MnCl.sub.2--4 H.sub.2O d.sup.5 58 400
TABLE-US-00008 TABLE VIII (Melting Point of Corresponding Proposed
Smoke Formulation Pyrotechnic Propellant Decomposition Catalyst
Metal Oxides) Metal Cation d Shell Electronic Melting Point Metal
Oxide Configuration .sup.1 (.degree. C.) Co.sub.3O.sub.4, d.sup.6
895 Fe.sub.2O.sub.3 d.sup.5 1539 MnO.sub.2, d.sup.2 535
EXAMPLE 3
[0049] In the embodiment illustrated by FIG. 1, line 100 and line
110 show the transmittance percentages of the RP smoke formulation
and the tested MATEAB white smoke formulation, which is defined by
the y-axis 120, during a time period, which is defined by the
x-axis 130. As indicated by FIG. 1, the transmittance percentage of
the RP smoke formulation is significantly higher than the
transmittance percentage of the tested MATEAB white smoke
formulation during a period of about 10 minutes. "About" as
described herein is used to capture internal measure errors.
[0050] Table IX lists the components of the said MATEAB white smoke
formulation.
TABLE-US-00009 TABLE IX (MATEAB White Smoke Formulation)
Concentration Component Function (wgt. %) Potassium Chlorate
Oxidizer 33.46 Sucrose Fuel 13.2 Melamine Obscurant Component 21.68
Triethanolamine Borate Obscurant Component 16.61 Acetoguanamine
Obscurant Component 14.21 Nitrocellulose Pellet Binder 0.83
[0051] In certain embodiments, the MATEAB white smoke formulation
(Table 4) when tested in an aerosol chamber exhibits higher
obscuring performance relative to conventional terephthalic acid
(TA) and red phosphorus RP smoke formulations.
[0052] Referring to FIG. 4, the MATEAB white smoke formulation has
a higher mass extinction coefficient value a (m.sup.2/g) at visible
light spectral wavelengths most sensitive to the photopic cone
(.lamda..apprxeq.550 nm) and scotopic rod cells
(.lamda..apprxeq.500 nm) responsible for human eye vision compared
to TA and RP smoke formulations. In chemistry, biochemistry,
molecular biology, or microbiology, the mass extinction coefficient
and the molar extinction coefficient (also called molar
absorptivity) are parameters defining how strongly a substance
absorbs light at a given wavelength, per mass density or per molar
concentration, respectively. The mass attenuation coefficient or
mass narrow beam attenuation coefficient of the volume of a
material characterizes how easily it can be penetrated by a beam of
light, sound, particles, or other energy or matter. In addition to
visible light, mass attenuation coefficients can be defined for
other electromagnetic radiation (such as X-rays), sound, or any
other beam that attenuates. The SI unit of mass attenuation
coefficient is the square metre per kilogram (m.sup.2/kg). Further,
the MATEAB white smoke formulations are shelf-stable and maintained
their obscuring performance and significant extinction coefficients
even after continuous isothermal aging of smoke pellet formulations
for longer than 8 weeks.
[0053] Table X summarizes the mass extinction coefficient values of
the MATEAB white smoke formulation, TA smoke, and RP smoke.
TABLE-US-00010 TABLE X (Mass Extinction Coefficients for Various
Smoke Formulation) .alpha. @ 550 nm .alpha. @ 500 nm Smoke
Formulation (m.sup.2/g) (m.sup.2/g) MATEAB 5.11 5.25 TA 4.85 4.71
RP 4.0 4.35
[0054] Table XI summarizes the mass extinction coefficient values
(m.sup.2/kg) of the MATEAB white smoke formulation and TA/PE
smoke.
TABLE-US-00011 Formulation 500 nm 550 nm 950 nm MATEAB 1.72 .+-.
0.25 1.90 .+-. 0.25 0.92 .+-. 0.10 TA/PE 0.54 .+-. 0.12 0.49 .+-.
0.12 0.20 .+-. .06
[0055] While the preferred embodiments of the present invention
have been illustrated in detail, it should be apparent that
modifications and adaptations to those embodiments may occur to one
skilled in the art without departing from the scope of the present
invention.
* * * * *