SOLID ROCKET PROPELLANT COMPOSITION AND METHOD FOR PRODUCING THE SOLID ROCKET PROPELLANT USING THE SAME

Abstract

A solid rocket propellant composition and method for producing the solid rocket propellant using the same is provided. The solid rocket composition includes nitrile-terminated polybutadiene (NTPB) as a binder, which is modified with nitrile groups and hydroxyl groups. The incorporation of NTPB with nitrile and hydroxyl groups improves the mechanical strength, flexibility, and overall durability of the propellant, leading to superior tensile strength and elongation compared to traditional binders. The propellant composition demonstrates excellent long-term stability, with minimal degradation in mechanical properties and performance metrics over extended periods. The method provides a robust solution for creating high-performance solid rocket propellants that can meet the stringent demands of various aerospace and defence applications.

Specification

Description:FIELD OF INVENTION
[0001] The present disclosure relates generally to the field of solid rocket propellants. In particular, the present disclosure pertains to a solid rocket propellant composition and method for producing the solid rocket propellant using the same.

BACKGROUND
[0002] Solid rocket propellants have been a cornerstone in propulsion systems for various aerospace and defense applications. One of the most widely used binders in these systems is Hydroxyl-Terminated Polybutadiene (HTPB), valued for its ability to act both as a binder and a fuel. HTPB-based propellants offer the flexibility and energy output required for modern propulsion needs. However, despite its widespread usage, traditional HTPB formulations face significant challenges, particularly in achieving optimal mechanical properties and maintaining consistent performance over time.
[0003] One of the primary challenges with HTPB-based propellants is their mechanical strength. The flexibility of HTPB is both a strength and a limitation. While it allows for good processability and elasticity, the tensile strength and elongation properties often fall short of requirements for high-performance applications. To address these issues, manufacturers typically introduce bonding agents and crosslinkers to enhance the mechanical stability of the propellant. However, these additives frequently provide only a narrow improvement in specific properties, such as tensile strength or elasticity, and can introduce complications in the formulation, leading to difficulties in balancing strength and flexibility.
[0004] The interaction between HTPB and solid fillers, such as ammonium perchlorate (AP) and RDX, is another area of concern. In composite propellants, the filler-binder interaction is critical for maintaining the mechanical integrity of the formulation. Poor bonding between the polymer binder and inorganic fillers can lead to issues like dewetting, where the filler particles become separated from the binder, reducing the structural integrity of the propellant. This can cause cracks or voids to form, especially under thermal or mechanical stress, ultimately compromising the performance and reliability of the propellant.
[0005] Additionally, the burn rate of composite solid propellants is another aspect that often lacks the precision needed for specific mission profiles. Achieving a consistent burn rate is crucial for applications where the thrust profile must be tightly controlled. In many conventional formulations, the interaction between the binder and fillers can unpredictably alter the combustion process, leading to variations in performance. This inconsistency presents a significant challenge in designing propellants that meet precise specifications for burn rate, particularly in precision-dependent aerospace applications.
[0006] The use of crosslinkers, such as Isophorone Diisocyanate (IPDI) and Desmodur N100, is a common practice to enhance the mechanical properties of HTPB-based propellants. These crosslinkers work by forming a cured polymer network that increases the mechanical stability of the propellant. However, these agents offer limited control over the final properties of the material. Manufacturers often rely on empirical methods to adjust the crosslink density, and finding the right balance between tensile strength, elongation, and flexibility can be challenging. Additionally, many crosslinkers are single-functional, meaning they improve only one aspect of the propellant's properties, which necessitates the use of multiple additives to achieve a broad range of mechanical improvements. This can lead to compatibility issues and complicate the manufacturing process.
[0007] Plasticizers and energetic additives, commonly added to adjust the viscosity, processability, and energy output of propellants, introduce further complications. While plasticizers can enhance certain properties, they often come with downsides such as phase separation, where the plasticizer separates from the binder over time, leading to mechanical degradation. Moreover, the volatility of many plasticizers means that they can evaporate during storage, reducing the stability and performance of the propellant. This issue is especially concerning for long-term storage, where maintaining the mechanical and energetic properties of the propellant is critical for safety and effectiveness.
[0008] Further, long-term stability is a crucial consideration for solid rocket propellants. In many applications, propellants may need to be stored for extended periods before use. Over time, propellant formulations that rely on traditional binders and additives can experience degradation in both mechanical properties and performance. Issues such as plasticizer evaporation, filler-binder separation, and oxidative degradation can reduce the reliability of the propellant, potentially compromising its performance when deployed.
[0009] Therefore, there is a need for formulations that can maintain propellant's integrity and performance over long durations, ensuring that the propellant remains safe and effective throughout its shelf life.

OBJECTS OF THE PRESENT DISCLOSURE
[0010] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0011] An object of the present invention is to provide a solid rocket propellant composition with enhanced mechanical strength and flexibility, addressing the limitations of traditional binders like Hydroxyl-Terminated Polybutadiene (HTPB).
[0012] An object of the present invention is to enhance the long-term stability of the propellant by reducing degradation over time.
[0013] Another object of the present invention is to provide a process for producing the solid rocket propellant using the solid rocket propellant composition.

SUMMARY
[0014] This summary is provided to introduce a selection of concepts in a simplified form that is further described below in the detailed description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
[0015] Aspects of the present disclosure relates to solid rocket propellants, specifically to advanced binder system that can overcome the mechanical limitations of traditional HTPB-based propellants, improve bonding with fillers, provide better control over burn rate, and ensure long-term stability without relying on a complex array of additives. The disclosure offers improvement in the structural integrity and mechanical stability of the propellant, thus preventing issues like dewetting, cracking, or separation during combustion or storage.
[0016] Accordingly, in an aspect, the present disclosure provides a solid rocket propellant composition comprising a nitrile-terminated polybutadiene (NTPB) binder, ammonium perchlorate (AP) as an oxidizer, research department explosive (RDX) as an energetic filler, and one or more crosslinking agents.
[0017] In various embodiments, the NTPB binder is present in an amount ranging from 10 to 20 wt%.
[0018] In various embodiments, the NTPB is modified with 2 to 5% nitrile groups and 1 to 3% hydroxyl groups.
[0019] In certain embodiments, the ammonium perchlate (AP) is present in an amount ranging from 60 to 80 wt%.
[0020] In various embodiments, the RDX is present in an amount ranging from 5 to 15 wt%.
[0021] In certain embodiments, the one or more crosslinking agents are present in an amount ranging from 2 to 7 wt%.
[0022] In certain embodiments, the one or more crosslinking agents are selected from a group consisting of Toluene Diisocyanate (TDI), Diglycidyl Ether of Bisphenol A (DGEBA), and a combination thereof.
[0023] In another aspect, the present disclosure provides a method for producing a solid rocket propellant using the solid rocket propellant composition, comprising steps of:
a) mixing 10 to 20 wt% of nitrile-terminated polybutadiene (NTPB), 60 to 80 wt% of ammonium perchlorate (AP), and 5 to 15 wt% of research department explosive (RDX) to obtain a mixture;
b) initiating crosslinking reaction in the mixture by adding 2 to 7 wt% of one or more crosslinking agents to the mixture; and
c) curing the crosslinked mixture of the step b) to form a crosslinked three-dimensional polymer network to obtain the solid rocket propellant.
[0024] In various embodiments, the curing at step c) is carried out at 60°C for a duration of 24 hours.
[0025] In certain embodiments, the produced solid rocket propellant exhibits a tensile strength between 8 MPa and 12 MPa, an elongation at break of 300%, and a burn rate between 1.0-1.5 cm/s.
[0026] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

BRIEF DESCRIPTION OF DRAWINGS
[0027] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0028] FIG. 1 illustrates an exemplary method for producing a solid rocket propellant using the solid rocket propellant composition, in accordance with an embodiment of the present disclosure.
[0029] FIG. 2 illustrates a) AP-NTPB propellant with aluminium and b) AP-NTPB propellant without aluminium, in accordance with an embodiment of the present disclosure.
[0030] FIG. 3 illustrates synthesized AP-NTPB Propellant, in accordance with an embodiment of the present disclosure.
[0031] FIG. 4 illustrates a) propellant ballistic evaluation motor setup and b) ballistic evaluation motor test firing, in accordance with an embodiment of the present disclosure.
[0032] FIG. 5 illustrates pressure and thrust vs time curve for test firing, in accordance with an embodiment of the present disclosure.



DETAILED DESCRIPTION OF THE INVENTION
[0033] The following is a detailed description of embodiments of the disclosure. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.
[0034] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0035] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0036] In some embodiments, numbers have been used for quantifying weight percentages, ratios, and so forth, to describe and claim certain embodiments of the invention and are to be understood as being modified in some instances by the term "about." Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0037] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0038] As used in the description herein and throughout the claims that follow, the meaning of "a," "an," and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise.
[0039] Unless the context requires otherwise, throughout the specification which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense that is as "including, but not limited to."
[0040] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0041] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. "such as") provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0042] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified.
[0043] The description that follows, and the embodiments described therein, is provided by way of illustration of an example, or examples, of particular embodiments of the principles and aspects of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the disclosure.
[0044] It should also be appreciated that the present invention can be implemented in numerous ways, including as a system, a method or a device. In this specification, these implementations, or any other form that the invention may take, may be referred to as processes. In general, the order of the steps of the disclosed processes may be altered within the scope of the invention.
[0045] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0046] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements a, b, and c, and a second embodiment comprises elements b and d, then the inventive subject matter is also considered to include other remaining combinations of a, b, c, or d, even if not explicitly disclosed.
[0047] The terms "solid rocket propellant composition" or "propellant composition" or "composition" or "formulation" or "propellant formulation" are used herein interchangeably with same meaning throughout the specification.
[0048] The terms "solid rocket propellant" or "propellant" are used herein interchangeably with same meaning throughout the specification
[0049] Aspects of the present disclosure relates to solid rocket propellants, specifically to advanced binder system that can overcome the mechanical limitations of traditional HTPB-based propellants, improve bonding with fillers, provide better control over burn rate, and ensure long-term stability without relying on a complex array of additives. The disclosure offers improvement in the structural integrity and mechanical stability of the propellant, thus preventing issues like dewetting, cracking, or separation during combustion or storage. The disclosure is applicable to aerospace, defence, and other industries that demand solid propellants with exceptional mechanical stability and enhanced combustion characteristics, particularly in extreme environments.
[0050] Accordingly, in an aspect, the present disclosure provides a solid rocket propellant composition including a nitrile-terminated polybutadiene (NTPB) binder, ammonium perchlorate (AP) as an oxidizer, research department explosive (RDX) as an energetic filler, and one or more crosslinking agents.
[0051] In various embodiment, NTPB acts as the primary binder in the propellant composition, providing structural integrity to the propellant by holding the various solid fillers together. The nitrile groups (-CN) in NTPB improve its bonding efficiency with the oxidizers and fillers, while the hydroxyl groups (-OH) contribute to crosslinking and mechanical properties. Compared to traditional binders like Hydroxyl-Terminated Polybutadiene (HTPB), NTPB enhances mechanical strength and flexibility due to its dual-functional groups. NTPB contributes to a more uniform distribution of fillers and leads to better mechanical stability and overall propellant performance. The NTPB remains stable over extended periods, reducing degradation.
[0052] In various embodiment, AP is a standard oxidizer used in solid rocket propellants. It provides the necessary oxygen for the combustion of the fuel components within the propellant. During combustion, AP breaks down to release oxygen, supporting the chemical reactions that produce the thrust. AP is highly energetic and efficient in providing oxygen, which ensures that the propellant burns evenly and at a consistent rate. AP's compatibility with NTPB ensures uniform mixing and better interaction, improving combustion performance.
[0053] In various embodiment, RDX is a high-energy explosive that serves as an energetic filler in the propellant. RDX's inclusion increases the overall energy output and improves the specific impulse (thrust) of the propellant. RDX enhances the performance by contributing to a faster and more powerful combustion. The use of RDX elevates the energy density of the propellant, making it suitable for applications that require high-performance propulsion. RDX's interaction with NTPB is critical for maintaining mechanical stability and optimizing burn rate. Crosslinking agents are chemicals that facilitate the formation of a three-dimensional polymer network within the NTPB binder. The crosslinking process strengthens the propellant's structure, ensuring that the binder holds the fillers more effectively, and enhances mechanical properties like tensile strength and flexibility. By crosslinking the NTPB binder, the mechanical strength of the propellant is increased, making it more resistant to physical stresses during storage and operation. Crosslinking also plays a crucial role in controlling the burn rate and ensuring that the propellant performs consistently. The combination of NTPB, AP, RDX, and crosslinking agents results in a propellant that exhibits enhanced mechanical properties such as high tensile strength and flexibility, uniform filler distribution, and controlled combustion characteristics. The crosslinking agents stabilize the binder, while AP and RDX provide a powerful oxidizer-fuel combination for efficient combustion. The composition addresses the limitations of traditional binders and propellant formulations, offering a higher level of performance for applications that demand precise control over energy release and structural integrity.
[0054] In various embodiments, the NTPB is present in an amount ranging from 10 to 20 wt%.
[0055] In various embodiments, the NTPB is modified with 2 to 5% nitrile groups and 1 to 3% hydroxyl groups. The nitrile groups in the NTPB enhance the filler-binder interaction, providing a filler dispersion uniformity of at least 95%. The nitrile and hydroxyl groups in the NTPB binder enhance bonding between the binder and solid fillers, providing improved mechanical stability and consistent performance throughout the propellant matrix.
[0056] In one embodiment, the use of nitrile-terminated polybutadiene (NTPB) binder reduces the need for additional additives by 50-60%, simplifying the formulation process and improving compatibility with ammonium perchlorate and RDX.
[0057] In certain embodiments, the ammonium perchlate (AP) is present in an amount ranging from 60 to 80 wt%.
[0058] In various embodiments, the RDX is present in an amount ranging from 5 to 15 wt%.
[0059] In certain embodiments, the one or more crosslinking agents are present in an amount ranging from 2 to 7 wt%. The crosslinking agents are selected to optimize the crosslink density, thereby balancing the propellant's tensile strength, elongation, and burn rate to meet specific application requirements. The crosslinking agents provide controlled mechanical and combustion characteristics, ensuring a burn rate of approximately 1.2 cm/s and maintaining the propellant's structural integrity under operational conditions.
[0060] In certain embodiments, the one or more crosslinking agents are selected from a group consisting of Toluene Diisocyanate (TDI), Diglycidyl Ether of Bisphenol A (DGEBA), and a combination thereof. TDI is highly reactive diisocyanate commonly used to form polyurethane networks. In the present formulation, TDI reacts with hydroxyl (-OH) groups on the Nitrile-Terminated Polybutadiene (NTPB) binder, facilitating the formation of the three-dimensional polymeric network. Which enhances the mechanical properties such as tensile strength, elongation, and durability of the final propellant. DGEBA is an epoxy-based crosslinker that reacts with both nitrile (-CN) and hydroxyl (-OH) groups. DGEBA forms stable, crosslinked structures that contribute to the overall strength and mechanical stability of the propellant matrix. The inclusion of DGEBA improves bonding between the binder and fillers (e.g., ammonium perchlorate and RDX), resulting in better filler dispersion and mechanical performance. Whereas the combination of crosslinking agents allows for precise control of the propellant's mechanical and combustion characteristics. By choosing different crosslinking agents, the formulation can balance properties such as burn rate, tensile strength, and elongation to meet specific operational requirements in aerospace and defence applications.
[0061] In another aspect, the present disclosure provides a method for producing a solid rocket propellant using the solid rocket propellant composition. The method improves upon traditional propellant formulations by offering a more robust, efficient, and predictable solid rocket propellant.
[0062] FIG. 1 illustrates the method for producing a solid rocket propellant using the solid rocket propellant composition, including steps of:
a) mixing 10 to 20 wt% of nitrile-terminated polybutadiene (NTPB), 60 to 80 wt% of ammonium perchlorate (AP), and 5 to 15 wt% of research department explosive (RDX) to obtain a mixture;
b) initiating crosslinking reaction in the mixture by adding 2 to 7 wt% of one or more crosslinking agents to the mixture; and
c) curing the crosslinked mixture of the step b) to form a crosslinked three-dimensional polymer network to obtain the solid rocket propellant.
[0063] In various embodiments, the curing at step c) is carried out at 60°C for a duration of 24 hours. The curing step initiates the crosslinking reaction, forming a three-dimensional network within the NTPB binder, which improves the propellant's mechanical strength and flexibility.
[0064] In one embodiment, the process begins with the synthesis of polybutadiene, a polymer formed by polymerizing butadiene monomers. The method of polymerization, such as solution polymerization or emulsion polymerization, is selected based on the desired molecular weight and properties. These properties are controlled by regulating factors such as temperature, pressure, and the type of catalyst used. Once the polybutadiene is synthesized, the polybutadiene undergoes chemical modification to introduce functional groups that will enhance its properties. In this case, nitrile groups (-CN) are chemically introduced into the polymer chain through reactions with nitrile-containing reagents. In a separate step, hydroxyl groups (-OH) are also added using hydroxyl-containing reagents. The presence of these groups gives the resulting polymer, Nitrile-Terminated Polybutadiene (NTPB), enhanced bonding capabilities and improved mechanical strength, making it a suitable binder for rocket propellants.
[0065] After the synthesis, the NTPB binder is purified to ensure that it is free of impurities that could affect the performance of the propellant. The purification process includes filtration, which removes unreacted chemicals or byproducts, and in some cases, solvent extraction to remove residual contaminants. Purity checks are conducted to guarantee that the NTPB meets the required quality standards, ensuring that the binder will not introduce inconsistencies into the propellant. With the purified NTPB binder in hand, the formulation process begins by mixing the binder with solid fillers. The key fillers used in this composition are ammonium perchlorate (AP), which acts as the oxidizer, and research department explosive (RDX), which serves as the energetic filler. The specific ratios of these components are adjusted based on the desired properties of the propellant, with the goal of ensuring a balance between mechanical strength, energy output, and burn rate. At this stage, crosslinking agents are introduced to the mixture. The crosslinking agents are crucial for initiating the formation of a network of chemical bonds between the NTPB molecules. The resulting crosslinked network greatly enhances the mechanical properties of the propellant, such as the propellant's tensile strength and stability under stress. To ensure a consistent and effective crosslinking process, the mixture is thoroughly stirred or agitated, allowing the crosslinking agents to be uniformly distributed throughout the binder and filler materials.
[0066] To achieve uniform performance in the final product, the mixture undergoes a homogenization step. The process ensures that the solid fillers AP and RDX and the crosslinking agents are evenly dispersed throughout the binder. Uniform dispersion is critical, as it directly influences the burn rate, energy output, and mechanical integrity of the propellant. The homogenization step helps eliminate any inconsistencies that might arise during combustion or under mechanical stresses. The final step in the production of the propellant involves curing the mixture. The mixture is placed in molds or casting devices, and then subjected to controlled heating at a set temperature, typically around 60°C, for a period of 24 hours. During this curing phase, the crosslinking agents react with the NTPB binder to form a three-dimensional polymer network, which solidifies the propellant into a stable, high-performance material. The curing time and temperature are carefully optimized to ensure that the crosslinking reaction proceeds effectively without causing degradation of the propellant. By the end of the curing process, the solid rocket propellant exhibits improved mechanical properties, such as enhanced tensile strength and elongation, as well as a controlled burn rate. The crosslinked NTPB binder, in conjunction with the uniformly distributed fillers, ensures that the propellant performs reliably during combustion, delivering consistent thrust and energy output. The method provides a robust solution for creating high-performance solid rocket propellants that can meet the stringent demands of various aerospace and defence applications.
[0067] In certain embodiments, the produced solid rocket propellant exhibits a tensile strength between 8 MPa and 12 MPa, an elongation at break of 300%, and a burn rate between 1.0-1.5 cm/s.
[0068] In one embodiment, the produced solid rocket propellant achieves an energy output between 2500 J/g and 3000 J/g. The propellant demonstrates long-term stability with less than 5% degradation in mechanical properties and performance after storage for 12 months at 25°C.
[0069] In an exemplary embodiment, the disclosure provides a propellant composition with aluminium. FIG. 2a shows the AP-NTPB propellant formulation with aluminum, which exhibits a metallic sheen, indicating the presence of aluminum powder that enhances its energetic performance by providing additional heat and increasing thrust during combustion. In contrast, the FIG. 2b grain represents the AP-NTPB propellant formulation without aluminum, characterized by a uniform, slightly matte finish. The formulation relies solely on ammonium perchlorate (AP) and nitrile-terminated polybutadiene (NTPB) as the binder, showcasing the essential bonding and mechanical properties of the NTPB without the added energy benefits of aluminum. Together, these visual representations highlight the versatility of NTPB as a binder in solid rocket propellants, allowing for tailored performance characteristics to meet specific application needs.
[0070] While the foregoing description discloses various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope of the disclosure. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

EXAMPLES
[0071] The present invention is further explained in the form of the following examples. However, it is to be understood that the foregoing examples are merely illustrative and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention.
Example 1: production of the solid rocket propellant using the composition
[0072] Materials: 15 wt% of weight Nitrile-Terminated Polybutadiene (NTPB) binder, 70 wt% ammonium perchlorate (AP), 10 wt% RDX (Research Department Explosive), and 5 wt% crosslinking agents.
[0073] Process: the NTPB binder was mixed with the solid fillers AP and RDX in a mixer. This step ensures that the solid fillers are uniformly distributed throughout the binder. The crosslinking agents were introduced into the mixture and thoroughly mixed, ensuring that the crosslinking agents are evenly distributed and can effectively initiate the crosslinking reaction. The blended propellant mixture was then cured at a temperature of 60°C for 24 hours. FIG.3 shows the produced propellant.
Example 2: Characterization studies carried out for the produced propellant
[0074] FIG.4 shows a) propellant ballistic evaluation motor setup and b) ballistic evaluation motor test firing. Ballistic evaluation refers to the assessment and analysis of the performance of propellant formulations based on their ballistic properties which are listed below:
[0075] Tensile Strength: Tensile strength was tested using a universal testing machine. The propellant sample was stretched until it breaks, and the maximum stress it can withstand was recorded. The propellant showed tensile strength of 10 MPa indicating that the propellant has a good balance of strength and flexibility, making it suitable for various applications.
[0076] Elongation: Elongation was measured by stretching the propellant sample until it breaks and determining the amount of stretch or deformation it can endure. The propellant exhibits elongation of 300% demonstrating that the propellant has excellent flexibility and can undergo significant deformation without failure.
[0077] Burn Rate: The burn rate was assessed by igniting the propellant and measuring how quickly it burns along its surface. The propellant exhibit burn rate of 1.2 cm/s indicating a moderate combustion speed, providing a balanced performance in terms of thrust generation and energy release.
[0078] Energy Output: Energy output was determined by measuring the amount of energy released during combustion. This is typically evaluated using calorimetric methods or specific impulse testing.
[0079] Long-Term Storage: The propellant was stored under controlled conditions e.g., temperature of 25 to 30ºC and humidity of 30 to 40% for extended periods to evaluate its stability and performance over time.
[0080] FIG. 5 exhibit the results from the test firing of the solid rocket propellant. The peak dynamic pressure reached 4.13 MPa, indicating significant fluctuations during combustion, which reflect the transient behavior of the combustion process. The peak static pressure measured was 3.73 MPa, demonstrating a stable combustion environment with some minor variations, indicating good consistency during the burn. The maximum thrust achieved was 1.51 Kg, with a rapid increase at the onset of combustion followed by a gradual decrease, showcasing the propellant's ability to produce thrust effectively during the burn.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0081] The incorporation of NTPB with nitrile and hydroxyl groups improves the mechanical strength, flexibility, and overall durability of the propellant, leading to superior tensile strength and elongation compared to traditional binders, ensuring that the propellant can withstand thermal and mechanical stresses during storage, handling, and operation.
[0082] The composition exhibit better filler dispersion, leading to improved uniformity and stability in the propellant composition. The enhanced interaction helps prevent issues like dewetting or cracking, especially under dynamic operating conditions.
[0083] The composition allows for precise control over the burn rate and energy output, which is essential for reliable and predictable propulsion.
[0084] The multifunctionality of the NTPB binder reduces the need for additional bonding agents, plasticizers, or other additives, simplifying the formulation process, reducing production complexity and minimizing potential compatibility issues between different components.
[0085] The propellant composition demonstrates excellent long-term stability, with minimal degradation in mechanical properties and performance metrics over extended periods.
 
, Claims:1. A solid rocket propellant composition, comprising, nitrile-terminated polybutadiene (NTPB) as a binder, ammonium perchlorate (AP) as an oxidizer, research department explosive (RDX) as an energetic filler, and one or more crosslinking agents.
2. The solid propellant composition as claimed in claim 1, wherein the NTPB is present in an amount ranging from 10 to 20 wt%.
3. The solid propellant composition as claimed in claim 1, wherein the NTPB is modified with 2 to 5% nitrile groups and 1 to 3% hydroxyl groups.
4. The solid propellant composition as claimed in claim 1, wherein the ammonium perchlate (AP) is present in an amount ranging from 60 to 80 wt%.
5. The solid propellant composition as claimed in claim 1, wherein the RDX is present in an amount ranging from 5 to 15 wt%.
6. The solid propellant composition as claimed in claim 1, wherein the one or more crosslinking agents are present in an amount ranging from 2 to 7 wt%.
7. The solid propellant composition as claimed in claim 1, wherein the one or more crosslinking agents are selected from a group consisting of Toluene Diisocyanate (TDI), Diglycidyl Ether of Bisphenol A (DGEBA), and a combination thereof.
8. A method for producing a solid rocket propellant using the solid rocket propellant composition of claim 1, comprising steps of:
a) mixing 10 to 20 wt% of nitrile-terminated polybutadiene (NTPB), 60 to 80 wt% of ammonium perchlorate (AP), and 5 to 15 wt% of research department explosive (RDX) to obtain a mixture;
b) initiating crosslinking reaction in the mixture by adding 2 to 7 wt% of one or more crosslinking agents to the mixture; and
c) curing the crosslinked mixture of the step b) to form a crosslinked three-dimensional polymer network to obtain the solid rocket propellant.
9. The method as claimed in claim 8, wherein the curing at step c) is carried out at 60°C for a duration of 24 hours.
10. The method as claimed in claim 8, wherein the produced solid rocket propellant exhibits a tensile strength between 8 MPa and 12 MPa, an elongation at break of 300%, and a burn rate between 1.0-1.5 cm/s.

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