HIGH MOLECULAR WEIGHT, HIGH CRYSTALLINE CAST NYLON PROPELLANT

FIELD OF THE INVENTION

[0001] The present technology relates to a cast nylon propellant having at least a high molecular weight and high crystallinity.

BACKGROUND OF THE INVENTION

[0002] Conventional cast nylon is known to exhibit high stiffness, tensile strength, impact resistance, heat resistance, abrasion resistance, vibration resistance, and compressive strength. Cast nylon can be easily machinable and relatively lightweight. Accordingly, cast nylon is suitable for use in place of parts made of metal and other plastics.

[0003] Cast nylon can be formed from a reaction involving a caprolactam with a high water content, as discussed in U.S. Patent Nos. 3,366,608 and 2,992,908, both of which are incorporated herein by reference. Caprolactam with a high water content is polymerized at high temperatures in the presence of an alkaline catalyst, such as sodium, potassium, or potassium hydroxide to form a cast nylon capable of many uses, including as a propellant. This reaction, however, requires additional chemical components to overcome interference from the water to encourage polymerization of the caprolactam into polyamide as opposed to unwanted side products.

[0004] Nevertheless, the high water content in this reaction creates extractables. For example, the water in the caprolactam also reacts with the alkali catalysts to form alkali hydroxides, e.g., NaOH, KOH, LiOH, etc. These alkali hydroxides exist in the final, polymerized cast nylon end product and therefore prevent complete polymerization of the caprolactam. These alkali hydroxide bi-products can react with the C-N bond of the polymerized end product and further disrupt its integrity. The resulting cast nylon produced by incomplete polymerization is fairly amorphous in consistency, containing polymerized pockets of form alkali hydroxides, e.g., NaOH and other non-polyamide monomer and oligomer extractables. Accordingly, these extractables cause the cast nylon to exhibit a low ratio of crystalline to amorphous structure and a lower melting point. Additionally, the increased ratio of amorphous structure may cause the cast nylon to have a decreased density and, accordingly, a decreased compactness. Further, the resulting cast nylon generally has a low molecular weight due to its amorphous structure resulting from the high levels of extractables present in its structure. A cast nylon of this particular structure may not be best suited for certain uses, e.g., as a propellant.

[0005] For example, the cast nylon taught in the '608 patent (identified above) uses a base component, N,N'-di-acyl bis-caprolactam, with a high water content, i.e., greater than 100 ppm. Some of this water appears in the polymerized cast nylon propellant creating a monomer content of approximately 8.9% in the finished cast nylon product. Additionally, when this type of caprolactam is polymerized in the presence of an alkali catalyst, some of the excess water content reacts with the alkali metal, forming unwanted side products such as alkali hydroxides. These side products appear in the polymerized cast nylon propellant, creating pockets of amorphous structure. This amorphous structure leads to burning at varying rates, with flashes and intense burns at dense pockets of the material, and slower burns at the amorphous areas. Therefore, the cast nylon propellant formed from the components described in the '608 patent makes for an unreliable form of propellant.

[0006] The technology taught in the '908 patent (identified above) discloses a cast nylon propellant. This particular cast nylon, however, also has significant drawbacks for use a propellant. The cast nylon propellant reacts a base polylactam with a high water content with an alkali catalyst, creating the same issues of unwanted side products described above. Further, the

'908 patent also identifies specific catalysts, e.g., sodium hydride, that can be harmful to the user in addition to obstructing the compete polymerization of the caprolactam. The resulting cast nylon propellant has an amorphous structure with varying pockets of dense and non-dense areas and therefore burns inconsistently, making it an unreliable source of propellant.

[0007] Further, both the cast nylons described in the '608 and '908 patents teach cast nylons that are in clear in color. A clear colored cast nylon propellant may allow the radiation from burning to permeate the surface of the cast nylon propellant and allow for softening of the material until it becomes putty-like in consistency. It is advantageous to have a solid, dense cast nylon propellant that maintains its shape throughout the burn process. Accordingly, other colored cast nylon propellants, e.g., black, exhibit improved characteristics over these clear cast nylon propellants taught in the prior art.

[0008] Therefore, there is a need in the art for a cast nylon propellant with a high molecular weight that exhibits characteristics including a high melting point, high crystallinity to amorphous ratio, and improved strength. The cast nylon propellant may also exhibit characteristics of improved burning and self support.

SUMMARY OF THE INVENTION

[0009] The present technology provides a nylon composition suitable for forming a cast nylon propellant having at least a high molecular weight and high crystallinity. In one embodiment, the cast nylon propellant may be used in aeronautics, rocketry, ballistics, pyrotechnics, and any other appropriate field. In another embodiment, the cast nylon propellant may be used as a fuel grain for rocket propulsion or other thrust-based engines. The composition for forming a nylon propellant composition includes an anion polymerized (AP)-caprolactam, e.g., epsilon-caprolactam, having a water content of less than 100 ppm, an impact modifier, a catalyst, an activator, and an additive. The composition may optionally include an oxidizer. The composition may optionally include a metal powder. [0010] In an embodiment, the AP-caprolactam can have a water content of less than 80 ppm. The impact modifier can be one or more of the following: acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, methacrylate/butadiene/styrene, poly(styrene-butadiene-styrene), styrene ethylene butylene styrene, maleic anhydride-modified styrene ethylene butylene styrene, chlorinated polyethylene elastomers, acrylics, cross-linked polyacrylates, ethylene propylene diene, maleic anhydride-modified ethylene propylene diene, styrene acrylonitrile -modified ethylene propylene diene, glycidyl methacrylate-modified ethylene-acrylate copolymers, ionomers, thermoplastic elastomers and plastomers, non-reactive, modified polyolefms, reactive, modified polyolefms, and N-2-alkyl-2-pyrrolidones, or a combination of two or more thereof.

The catalyst can be an alkali metal lactam, such as sodium caprolactamate. The activator can be a monofunctional polymeric isocyanate, difunctional polymeric isocyanate, or a combination of two or more thereof. In particular, the activator can be a hexamethylene diisocyanate, isophorone diisocyanate, hexamethylene diacyl bromide, hexamethylene diacyl chloride, or a combination of two or more thereof. The additive can be a black colorant that provides the cast nylon propellant with potentially advantageous properties depending on its use. The composition can form a cast nylon propellant through an anionic polymerization reaction at less than 140° C.

[0011] The resulting cast nylon propellant can have a relatively high molecular weight, uniformity in its polyamide structure, compactness, minimal to no formation of extractables, and a relatively high crystallinity to amorphous ratio. Further, the cast nylon propellant may include less than 2% extractables, and can include less than 1% NaOH. The cast nylon propellant can have a relatively high molecular weight of at least 250,000 g/mol to 500,000 g/mol. The cast nylon propellant exhibits at least a 15% crystalline structure. The cast nylon propellant can exhibit at least a 30% crystalline structure.

[0012] This dense, compact cast nylon propellant having a high crystalline structure with low amounts of extractables allows for uniform burning. An amorphous structure may burn at varying rates, with flashes and intense burns at dense pockets of the material, and slower burns at less dense areas. The structure of the cast nylon propellant of the present technology allows for a uniform burn rate and makes it a reliable source of fuel, especially as compared to standard propulsion fuel sources like polybutadiene or cast nylon propellants formed from high-water containing caprolactams.

[0013] The cast nylon propellant may be formed as a self-supporting, monolithic article having at least one internal channel and chambers. The internal channel may be configured to hold an oxidizer. When the oxidizer is burned during propulsion, the black coloring of the cast nylon propellant prevents any radiation from penetrating the underlying surface of the nylon. This prevents the remainder of the casting from softening and becoming non-self-supporting. A cast nylon propellant that is black has advantages over clear-colored cast nylon propellants that allow the radiation to permeate the surface of the cast nylon propellant and allow for softening of the material until it becomes putty-like in consistency. Here, however, the black cast nylon propellant maintains its strength and allows for consistent burning throughout the entire propulsion. Further, the internal channel may allow for the flow of gases and power production through the cast nylon propellant, thereby preventing cracks and other problems during the heating process.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present teachings may be better understood by reference to the following detailed description taken in connection with the following illustrations, wherein:

[0015] Figure 1 is a perspective view of an embodiment of a cast nylon propellant;

[0016] Figure 2 is a plan view of an embodiment of a cast nylon propellant; and

[0017] Figure 3 is a cross-sectional view of along the line C-C of the cast nylon propellant.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present technology provides a nylon composition suitable for forming a cast nylon propellant having at least a high molecular weight and high crystallinity. The resulting cast nylon propellant may have a high crystallinity to amorphous ratio, with limited to no extractables. Additionally, the resulting cast nylon propellant may exhibit properties such as enhanced black body radiation, improved strength and crack resistance, favorable electrical resistance, and a high melting point. The advantageous characteristics of the cast nylon also allow for its use as a propellant for use in aeronautics, rocketry, ballistics, pyrotechnics, and any other appropriate field. In one embodiment, the cast nylon propellant may be used as a fuel grain for rocket propulsion or other thrust-based engines. The nylon composition can be used to form a variety of components, including, but not limited to, plates, rods, tubes, containers, bars, discs, rings, and can be used, for example, in the construction, food processing, waste water, material handling, oil and gas, steel, agriculture, mining, and marine industries.

[0019] The nylon composition comprises a base mixture and an additive. The base mixture of the nylon composition comprises AP-caprolactam, an impact modifier, a catalyst, and an activator. The nylon composition may also comprise additional additives and filler components. The nylon composition may also include an oxidizer. The nylon composition may be configured to form a cast nylon propellant with improved properties over the current cast nylon propellants.

[0020] The AP-caprolactam used can have a low viscosity (4.87 mPa-s at 100° C) and a low melting point (T _m = 69° C). The AP-caprolactam may be used in a liquid form or in a solid form, such as flakes. It may have a moisture content of less than 110 ppm, less than 105 ppm, less than 100 ppm, less than 95 ppm, less than 90 ppm, less than 85 ppm, less than 80 ppm, less than 75 ppm, or less than 70 ppm. The AP-caprolactam can be moisture-free. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non- disclosed ranges. The use of AP-caprolactam that is minimum moisture or is moisture free can minimize any potential interference of water during the polymerization process. In one embodiment, the AP-caprolactam is epsilon-caprolactam. [0021] The AP-caprolactam may be provided in any appropriate amount in order to create a ratio with the other components that will produce the nylon composition. The AP- caprolactam may be the majority component of the nylon composition. For example, the nylon composition can comprise from about 50 - 99 weight percent of AP-caprolactam; from about 60 - 96 weight percent of AP-caprolactam; from about 70 - 93 weight percent of AP-caprolactam; or about 80 - 90 weight percent of AP-caprolactam. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-disclosed ranges.

[0022] The nylon composition can include an impact modifier suitable for increasing flexibility and impact strength of the nylon composition. The impact modifier may be elastomeric or rubbery in nature, with a lower modulus than the AP-caprolactam. Examples of suitable impact modifiers include, but are not limited to, acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, methacrylate/butadiene/styrene, poly(styrene-butadiene-styrene), styrene ethylene butylene styrene, maleic anhydride-modified styrene ethylene butylene styrene, chlorinated polyethylene elastomers, acrylics, cross-linked polyacrylates, ethylene propylene diene, maleic anhydride-modified ethylene propylene diene, styrene acrylonitrile -modified ethylene propylene diene, glycidyl methacrylate-modified ethylene-acrylate copolymers, ionomers, thermoplastic elastomers and plastomers, non-reactive, modified polyolefms, reactive, modified polyolefms, N-2-alkyl-2-pyrrolidones, and combinations of two or more thereof.

[0023] The impact modifier may be provided in any appropriate amount in order to create a ratio with the other components that will produce the nylon composition. The impact modifier may be a minority component of the nylon composition. For example, the nylon composition can comprise less than 10 weight percent of impact modifier; less than 8 weight percent of impact modifier; less than 6 weight percent of impact modifier; less than 4 weight percent of impact modifier; less than 2 weight percent of impact modifier; or less than 1 weight percent of impact modifier. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-disclosed ranges. [0024] The nylon composition also can include a catalyst suitable for speeding up the reaction. The catalyst may be any catalyst known for anionic polymerization of lactams in either a solid or liquid form. Examples of suitable catalysts include, but are not limited to, alkali metal lactams comprising lithium, sodium, potassium, rubidium, cesium, and francium. Additional examples of suitable catalysts include sodium-dicaprolactamato-bis-(2-methozyethoxy)- aluminate and Grignard-based catalysts such as Mg(OH)Br. In one embodiment, the catalyst is sodium caprolactamate.

[0025] The catalyst may be provided in any appropriate amount in order to create a ratio with the other components that will produce the nylon composition. The catalyst may be a minority component of the nylon composition. For example, the nylon composition can comprise less than 10 weight percent of catalyst; less than 8 weight percent of catalyst; less than 6 weight percent of catalyst; less than 4 weight percent of catalyst; less than 2 weight percent of catalyst; or less than 1 weight percent of catalyst. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-disclosed ranges.

[0026] The nylon composition can include an activator suitable for controlling the speed and quality of the reaction to create the nylon composition. The activator may be any activator known for anionic polymerization of lactams in either a solid or liquid form. Examples of suitable activators include, but are not limited to, monofunctional polymeric isocyanates, difunctional polymeric isocyanates activators, or a combination of two or more thereof. In one embodiment, the activator is selected from the group comprising hexamethylene diisocyanate, isophorone diisocyanate, hexamethylene diacyl bromide, hexamethylene diacyl chloride, or a combination of two or more thereof. In a different embodiment, the activator is difunctional hexamethylene- 1 ,6-dicarbamoyl-caprolactam.

[0027] The activator may be provided in any appropriate amount in order to create a ratio with the other components that will produce the nylon composition. The activator may be a minority component of the nylon composition. For example, the nylon composition can comprise less than 10 weight percent of activator; less than 8 weight percent of activator; less than 6 weight percent of activator; less than 4 weight percent of activator; less than 2 weight percent of activator; less than 1 weight percent of activator; or less than 0.5 weight percent of activator. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-disclosed ranges.

[0028] The nylon composition also can include an additive to provide specific strength or stiffness properties in the desired final molded products. For example, the additive may be high- molecular-weight polyol, aliphatic polyisocyanate, solid blocked diisocyanate, laurinlactam, aromatic polycarbodiimide, dimeric toluene -2.4-diisocyanate, molybdenum disulphide, silicon oil, nonyl phenol ethoxylate, silicon dioxide, polyoxypropylene triamine, or a combination of two or more thereof. Also, the additives may be suitable for making the nylon composition black in color and therefore providing the resulting cast nylon propellant with enhanced black body radiation properties. The additive may be any suitable material, including, but not limited to, a colorant.

[0029] The additive may be provided in any appropriate amount in order to create a ratio with the other components that will produce the nylon composition. The additive may be a minority component of the nylon composition. For example, the nylon composition can comprise less than 4 weight percent of additive; less than 3 weight percent of additive; less than 3 weight percent of additive; less than 2 weight percent of additive; less than 1 weight percent of additive; less than 0.8 weight percent of additive; or less than 0.5 weight percent of additive. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-disclosed ranges.

[0030] The nylon composition also can include an oxidizer to oxidize another substance.

In one embodiment, the oxidizer would support the combustion of fuel, or in this case, the cast nylon. The oxidizer may be any suitable material, including, but not limited to, oxygen; ozone; hydrogen peroxide and other inorganic peroxides; fluorine, chlorine, and other halogens; nitric acid and other nitrate compounds; sulfuric acid; peroxydisulfuric acid; peroxymonosulfuric acid; chlorite, chlorate, perchlorate, and other analogous halogen compounds; hypochlorite and other hypohalite compounds, including household bleach; hexavalent chromium compounds such as chromic and dichromic acids and chromium trioxide, pyridinium chlorochromate, and chromate/dichromate compounds; permanganate compounds, e.g., potassium permanganate; sodium perborate; nitrous oxide; silver oxide; osmium tetroxide; potassium nitrate; Tollens' reagent; 2,2'-dipyridyldisulfide; or a combination of two or more thereof.

[0031] The oxidizer may be provided in any appropriate amount in order to create a ratio with the other components that will produce the nylon composition. The oxidizer may be a minority component of the nylon composition. For example, the nylon composition can comprise less than 4 weight percent of oxidizer; less than 3 weight percent of oxidizer; less than 3 weight percent of oxidizer; less than 2 weight percent of oxidizer; less than 1 weight percent of oxidizer; less than 0.8 weight percent of oxidizer; or less than 0.5 weight percent of oxidizer. In one embodiment, there is no oxidizer in the nylon composition. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-disclosed ranges.

[0032] The nylon composition also can include a metal powder to enhance the burning rate of the cast nylon propellant. The metal powder may be any suitable metal, including, but not limited to, aluminum, magnesium, or a combination of two or more thereof. The metal powder may be any appropriate size. In one embodiment, the metal powder is microscopic in size.

[0033] The metal powder may be provided in any appropriate amount in order to create a ratio with the other components that will produce the nylon composition. The metal powder may be a minority component of the nylon composition. For example, the nylon composition can comprise less than 20 weight percent of metal powder; less than 18 weight percent of metal powder; less than 16 weight percent of metal powder; less than 14 weight percent of metal powder; less than 12 weight percent of metal powder; less than 10 weight percent of metal powder; less than 8 weight percent of metal powder; less than 6 weight percent of metal powder; less than 4 weight percent of metal powder; or less than 2 weight percent of metal powder. In one embodiment, there is no metal powder in the nylon composition. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-disclosed ranges.

[0034] The nylon composition can be prepared by combining the AP-caprolactam, the impact modifier, the catalyst, the activator, and the additive, as well as any optional filler materials and oxidizers. In an embodiment, the AP-caprolactam may be a preformed material that is added to the other components of the nylon composition. In another embodiment, the AP- caprolactam may be formed in-situ. That is, the components for forming the base promoter may be added to the other components of the nylon composition, and the AP-caprolactam may be formed as part of the reaction process in creating the nylon composition.

[0035] A polymerization reaction creates the cast nylon propellant from the nylon composition. The temperature for the polymerization reaction is generally kept under 200° C; and can be kept under 180° C; 160° C; 140° C; or under 120° C. Here, as elsewhere in the specification and claims, numerical values may be combined to form new and non-disclosed ranges.

[0036] First, the AP-caprolactam, impact modifier, catalyst, activator, and additive are prepared and combined. An oxidizer may be added to the composition. A metal powder may be added to the composition. In one embodiment, the AP-caprolactam reacts with the catalyst sodium caprolactam. The low water content of AP-caprolactam increases the uniformity of the polyamide structure formed in the cast nylon propellant. The lower the water content of the AP- caprolactam, the lower the amount of undesirable NaOH produced in the reaction. According to the present technology, the amount of NaOH produced is essentially negligible, e.g., the amount of NaOH in the end product is less than 1%, less than 0.5%, or less than 0.25%. The negligible of NaOH produced is important as NaOH can break the C-N chains of the cast nylon propellant and create a less uniform structure in the end product.

[0037] As there is less water to react with sodium with the present technology, there is also an increased rate of polymerization and, consequently, a decreased amount of side products, i.e., extractables, including non-polyamide monomers and oligomers side products. In one embodiment, the amount of extractables is less than 5% of the cast nylon propellant; less than 4% of the cast nylon propellant; less than 3% of the cast nylon propellant; less than 2% of the cast nylon propellant; or less than 1% of the cast nylon propellant. This lack of extractables leads to a dense, compact, uniform structure in the cast nylon propellant.

[0038] The cast nylon propellant has a condensed, crystalline structure comprising a larger crystalline structure portion versus amorphous structures. In one embodiment, the cast nylon propellant has a crystalline to amorphous structure of at least 15% of the end product; at least 20% of the end product; at least 25% of the end product; at least 30% of the end product; at least 35%) of the end product; at least 40%> of the end product; at least 45% of the end product; or at least 50%> of the end product. Due to its crystalline structure, the resulting cast nylon propellant, therefore, is dense and compact.

[0039] The geometry of a cast nylon propellant determines its exposed areas, i.e., potential burning surface. In order to create a stable and constant burn pattern, a favorable geometry must be selected. The burning surface and the composition of the cast nylon propellant will determine the rate of regression, often called the "burn rate," which is generally measured in millimeters/second or inches/second. The burn rate can differ significantly for various propellant types, and can differ even among various cast nylon propellant types.

[0040] Accordingly, the dense, compact geometry of a cast nylon propellant having a high crystalline structure with low amounts of extractables allows for uniform burn rate, i.e., a constant burning rate from the beginning of the burn process through the end. An amorphous structure may burn at varying rates, with flashes and intense burns at dense pockets of the material, and slower burns at less dense areas. The structure of the cast nylon propellant of the present technology allows for a uniform burn rate and makes it a reliable source of fuel, especially as compared to standard propulsion fuel sources like polybutadiene or cast nylon propellants formed from high-water containing caprolactams.

[0041] Accordingly, this dense, high crystalline cast nylon propellant therefore has a high molecular weight. The molecular weight may range from at least 250,000 to 500,000 g/mol. In one embodiment, the molecular weight range is at least 250,000 - 500,000 g/mol; at least 275,000 - 475,000 g/mol; at least 300,000 - 450,000 g/mol; at least 325,000 - 425,000 g/mol; or at least 350,000 - 400,000 g/mol.

[0042] The geometry and composition of the cast nylon propellant allow for a sufficient initial burning temperature of the cast nylon propellant. Further, the geometry and composition of the cast nylon propellant also allow the cast nylon to maintain a high melting point. In one embodiment, the melting point is at least 170° C; at least 180° C; at least 190° C; at least 200° C; at least 210° C; at least 220° C; at least at least 230° C; at least 240° C; at least 250° C; at least 260° C; or at least 270° C.

[0043] The cast nylon propellant also can exhibit black body radiation characteristics. A black body is a theoretical object that absorbs all of the radiation that it receives and emits all frequencies of electromagnetic radiation, i.e., it does not reflect any electromagnetic radiation, nor does it allow any electromagnetic radiation to pass through it. The energy that a black body absorbs heats the object, and then it will emit its own radiation. Therefore, black body radiation is a type of electromagnetic radiation within or surrounding an object in thermodynamic equilibrium with its environment or emitted by an opaque and non-reflective black body held at constant, uniform temperature. The radiation has a specific spectrum and intensity that depends only on the temperature of the black body. Real objects never behave as ideal black bodies; rather the emitted radiation at a given frequency is a fraction of what the ideal emission would be. The emissivity of a material specifies how well a real body radiates energy as compared with a black body. This emissivity depends on factors such as temperature, emission angle, and wavelength.

[0044] The hotter the black body, the more electromagnetic radiation it emits at all wavelengths. The electromagnetic radiation is released in photons. The higher the energy of the photon, the bluer the light, and the shorter the wavelength. The lower energy of the photon, the redder the light, and the longer the wavelength. These released photons only exist at certain quantized energy levels. However, because the increment between energy levels is so small, the spectrum being emitted by the black body appears to be continuous.

[0045] As a black body object in thermal equilibrium is an ideal emitter, i.e., at every frequency, it emits at least as much energy as any other body at the same temperature, a black body object is a choice material for use as a propellant. Accordingly, the resulting cast nylon propellant may be used as a propellant due to its black body radiation qualities.

[0046] A cast nylon propellant may be enhanced by black body radiation qualities. The cast nylon propellant that contains an oxidizer in the original composition may be able to burn with the addition of a heat source. Additionally, an oxidizer may be flushed through the cast nylon after it is formed. When the oxidizer is burning the cast nylon propellant during combustion, the black color of the nylon prevents any radiation from penetrating the underlying surface of the nylon. As a result, this prevents the rest of the cast nylon propellant from softening and becoming non-self supporting. In embodiments where the cast nylon propellant is clear in color, after a few seconds of ignition, the radiation from the burning surface of the cast nylon propellant penetrates through the core of the remaining cast nylon propellant and softens the material to the point of a putty-like consistency. This softer, putty-like cast nylon propellant is no longer self-supporting and is not as reliable of a propellant as it loses it shape and burns less consistently. If, however, the nylon is black, the radiation cannot penetrate through the cast nylon propellant as the black color reflects any penetration of the radiation into the polymer matrix immediately below the combusting surface of the cast nylon. The cast nylon propellant does not lose any integral strength, and, therefore, stays consistently strong throughout the entire burn cycle and remains self-supporting.

[0047] The resulting cast nylon propellant may be prepared in a variety of manners. The cast nylon propellant composition may be formed through any variety of casting techniques (e.g., pour cast, injection molded, and/or spun cast) to manufacture cast nylon propellant in a variety of shapes, including, but not limited to, plates, rods, tubes, containers, bars, discs, rings, and other custom shapes. The cast nylon propellant may be formed by using various inserts in the molding process, in order to create custom shapes, including inner channels and chambers. These parts may be used in a variety of industries and for a variety of uses. In one embodiment, the cast nylon propellant may be used as a fuel to propel vehicles (e.g., airplanes, rockets, automobiles, etc.), as well as use in the fields of ballistics, pyrotechnics, aeronautics, rocketry, or any other appropriate field.

[0048] A cast nylon propellant may be formed through in-situ polymerization as a monolithic, self-supporting casting. The in-situ polymerization of the cast nylon components allows for the formation of a monolithic structure with a free design including open chambers, as shown in Figures 1-3. The cast nylon propellant 10 may include a frame having an upper surface 12 and lower surface 14 each connected by a side surface 16. The cast nylon propellant 10 may include at least one internal channel 18, formed in the original casting, i.e., no additional casting is required. The internal channel 18 may have two openings, one on the upper surface 12 and one on the lower surface 14. In one embodiment, the internal channel 18 may be positioned in appropriately the center of the cast nylon propellant 10 and may span the length of the cast nylon propellant. In other embodiments, the internal channel may be placed off-center or in other locations in the cast nylon propellant. The internal channel may be configured to receive an oxidizer or any other appropriate composition. An internal channel may provide stress relief to the cast nylon propellant by allowing for the flow of gases and power production from oxidizers and other chemicals. A completely solid cast nylon propellant with no internal channel may have a tendency to form cracks when subjected to changes in temperature, such as the extreme heating required for a propellant. Cracks in the cast nylon propellant are undesirable because may cause an uneven burn. To avoid the formation of these uncontrolled cracks, an internal channel may be included.

[0049] Additionally, the cast nylon propellant 10 may include at least one chamber 20.

The cast nylon propellant 10 is not limited in the number in the number of chambers that it may include. In one embodiment, the cast nylon propellant may include one chamber; two chambers; three chambers; four chambers; five chambers, six chambers; seven chambers; eight chambers nine chambers; ten chambers; or even more chambers. As shown in Figures 1-3, the cast nylon propellant may include eight chambers 20. The chamber 20 may have two openings, one on the upper side 12 of the cast nylon propellant 10 and the other opening on the lower end 14 of the cast nylon propellant 14. For the reasons discussed above, chambers also aid in a cast nylon propellant's crack-resistance, especially when the cast nylon propellant is subject to changes in temperature, such as extreme heating. Accordingly, the structure of the cast nylon propellant may be self-supporting for combustion, propulsion, or any other appropriate action based on both the material composition and the geometry.

[0050] Additionally, the composition and the geometry of the cast nylon propellant, coupled with its high molecular weight, allow for a steady, even burn from the interior of the cast nylon, i.e., in the inner channel, to the exterior of the cast nylon. This allows for the burn to remain steady without a loss of thrust during burning. The cast nylon propellant also maintains an optimal inner channel pressure, local static pressure, and motor acceleration and spin. Further, the composition and geometry of the cast nylon propellant allow for optimal velocity of the combustion gases flowing parallel to the burning surfaces but within the cast nylon propellant, i.e., in its inner channel and along the exterior surfaces of the cast nylon.

[0051] As discussed above, the cast nylon propellant may contain any appropriate configuration of inner channels and chambers. By varying the geometry of the cast nylon propellant by varying the number and size of the inner channels and chambers, the burn rate may also vary. In one embodiment, a single vehicle motor (e.g., airplanes, rockets, automobiles, etc.) may necessitate the use of multiple cast nylon propellants, each designed differently which allows for the user to achieve an overall desired burn and thrust rate for the entire motor.

[0052] While the technology has been described with reference to various exemplary embodiments, it will be appreciated that modifications may occur to those skilled in the art, and the present application is intended to cover such modifications and inventions that fall within the spirit of the invention.