Nontoxic and Non-incendiary Obscurant Compositions and Method of Using Same

Info

Publication number: 20180141880
Type: Application
Filed: Nov 23, 2016
Publication Date: May 24, 2018
Inventor: John L. Lombardi (Tuscon, AZ)
Application Number: 15/360,265

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.

Description

Description

FIELD OF THE INVENTION

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

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

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.

Applicant's white smoke formulations exhibit low peak combustion temperatures, high visual obstruction properties, and gradient burn characteristics.

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

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:

FIG. 1 illustrates transmittance percentages of RP smoke and the melamine/acetoguanamine triazine borate (MATEAB) white smoke formulation;

FIG. 2 illustrates different embodiments of smoking devices with gradient burn characteristics;

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;

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;

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;

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;

FIG. 4 shows that the MATEAB white smoke formulation has a higher mass extinction coefficient value a (m²/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

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.

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.

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° 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.

Applicant's disclosure benefits in terms of both enhanced military capability coupled with cost reduction. Such benefits are described in greater details below.

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.

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.

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).

Applicant has developed smoke formulations suitable for 155 mm smoke canister munitions having lower peak combustion temperatures (T<400° 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.

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 (MnO₂), cobalt oxide (Co₃O₄), iron oxide (Fe₂O₃), manganese chloride tetrahydrate (MnCl₂-4H₂O), cobalt chloride hexahydrate (CoCl₂-6H₂O), iron chloride hexahydrate (FeCl₃-6H2O), 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.

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.

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° 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.

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° 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.

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.

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.

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.

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.

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

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:

In certain embodiments, OCC compounds comprises pentaerythritol borate 8, having a structure of

and/or triethanolamine phosphate (TEAP) 7, having a structure of

TEAB 6 can be efficiently sublimed at low temperatures (T<250° 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.

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.

Table 1 summarizes the properties of several obscurant compounds.

TABLE 1 Total Number of Hydrogen Density ΔH_vap Bonding Compound Structure δ (cal^1/2ml^−1/2)^a (g/mL)^b (cal/g) Sites^b Terephthalic Acid (TA) 12.0 1.51 99 6 Melamine 16.0 1.66 155 12 Acetoguanamine 13.7 1.39 135 9 Triethanolamine Borate (TEAB) 8.15 1.13 58.8 4 Pentaerythritol Phosphate Alcohol (PEPA) 10.3 1.35 78.4 6 ^aδ values calculated from Van Krevelen, D. W. Properties of Polymers, 3^rded.; Elsevier: New York, 1997.⁴ ^bDensity values and H-bonding sites calculated using ACD/Labs Software V 11.01 on CAS SciFinder Scholar.

EXAMPLE 2

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° 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 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 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 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 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

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

and/or Chlorez chlorinated wax having a structure of

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.

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.

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.

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.

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.

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

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).

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 m³chamber 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.

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.

Table VII and Table VIII summarize the properties of several chlorate oxidizers and metal oxides.

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 ¹ (° C.) (° C.) ¹ CoCl₂—6H₂O d⁷ 86 317 FeCl₃6H₂O d⁵ 37 340 MnCl₂—4 H₂O d⁵ 58 400

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 ¹ (° C.) Co₃O₄, d⁶ 895 Fe₂O₃ d⁵ 1539 MnO₂, d² 535

EXAMPLE 3

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.

Table IX lists the components of the said MATEAB white smoke formulation.

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

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.

Referring to FIG. 4, the MATEAB white smoke formulation has a higher mass extinction coefficient value a (m²/g) at visible light spectral wavelengths most sensitive to the photopic cone (λ≈550 nm) and scotopic rod cells (λ≈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 (m²/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.

Table X summarizes the mass extinction coefficient values of the MATEAB white smoke formulation, TA smoke, and RP smoke.

TABLE X (Mass Extinction Coefficients for Various Smoke Formulation) α @ 550 nm α @ 500 nm Smoke Formulation (m²/g) (m²/g) MATEAB 5.11 5.25 TA 4.85 4.71 RP 4.0 4.35

Table XI summarizes the mass extinction coefficient values (m²/kg) of the MATEAB white smoke formulation and TA/PE smoke.

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

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.

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° 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 (MnO2), cobalt oxide (Co3O4), iron oxide (Fe2O3), manganese chloride tetrahydrate (MnCl2-4H2O), cobalt chloride hexahydrate (CoCl2-6H2O), and iron chloride hexahydrate (FeCl3-6H2O).

20. The composition of claim 19, wherein said burn rate accelerant is MnO2 and causes over about 20% increase in burn rate.