A method for evaluating the interface interaction between filler and matrix of composite solid propellant

Abstract

The present solution discloses a method for evaluating the interfacial interaction between filler and matrix of composite solid propellant, and the method includes: evaluating the interfacial interaction between filler and matrix based on the comparison of characteristic parameters of unfilled matrix and matrix filled with filler or matrix filled with different fillers; the characteristic parameters include one or both of the transverse relaxation time of hydrogen atoms and the apparent crosslinking density. The present invention is based on low-field nuclear magnetic resonance technology, and has the characteristics of mature technology, simple operation and rapid experiment, and can obtain experimental results in a relatively short time.

Description

Technical Field

[0001] The present invention relates to the technical field of composite solid propellants, and particularly relates to a method for evaluating the interfacial interaction between fillers and matrix of a composite solid propellant. Background Art

[0002] Composite solid propellant is an energetic composite material with specific properties, mainly composed of 10% - 20% of a polymer binder matrix, 50% - 60% of oxidizer particles, and 10% - 20% of metal fuel. As an engineering component of a rocket engine, like the casing, during manufacturing, transportation, ignition, and flight, the solid propellant has to withstand loads such as thermal stress, shock, vibration, acceleration, and ignition pressure. At the same time, it must also endure various environmental tests during long-term storage and standby. It is required that the propellant grain has relatively high tensile strength and elongation at a certain range of temperature and strain rate. Otherwise, new cracks will appear in the propellant, ultimately leading to out-of-control combustion and even engine explosion. Therefore, studying the mechanical properties of solid propellants is of great significance.

[0003] The mechanical properties of composite solid propellants depend on the "weak link" among the filler, matrix, and filler / matrix interface. As the main component of a solid rocket engine, the mechanical properties of composite solid propellants are the key basic properties to ensure the structural integrity of the solid rocket engine, and to ensure the normal operation of the engine and its reliable fulfillment of combat missions. Therefore, how to quickly and accurately evaluate the interfacial interaction between fillers and matrix is of great significance for improving the mechanical properties of composite solid propellants, analyzing the structural integrity, and analyzing the failure mechanism. Summary of the Invention

[0004] An object of the present solution is to provide a method for evaluating the interfacial interaction between fillers and matrix of a composite solid propellant, which can simply and quickly evaluate the interfacial interaction between fillers and matrix in the composite solid propellant.

[0005] To achieve the above object, the present solution is as follows:

[0006] A method for evaluating the interfacial interaction between fillers and matrix, the method comprising:

[0007] Based on the comparison of characteristic parameters of a non-filled matrix and a matrix filled with fillers, or

[0008] Based on the comparison of characteristic parameters of matrices filled with different fillers,

[0009] evaluate the interfacial interaction between fillers and matrix; the characteristic parameters include any one of the transverse relaxation time of hydrogen atoms and the apparent crosslink density.

[0010] Preferably, when the hydrogen atom transverse relaxation time is selected as the characteristic parameter, the hydrogen atom transverse relaxation times of the unfilled matrix and the matrix filled with the filler are measured respectively. If the hydrogen atom transverse relaxation time of the matrix filled with the filler is less than that of the unfilled matrix, there is a strong interfacial interaction between the matrix filled with the filler and the filler.

[0011] Preferably, when the apparent crosslinking density is selected as the characteristic parameter, the apparent crosslinking densities of the unfilled matrix and the matrix filled with the filler are measured respectively. If the apparent crosslinking density of the matrix filled with the filler is greater than that of the unfilled matrix, there is a strong interfacial interaction between the matrix filled with the filler and the filler.

[0012] Preferably, when the hydrogen atom transverse relaxation time is selected as the characteristic parameter, the hydrogen atom transverse relaxation times of the matrix filled with the first filler and the matrix filled with the second filler are measured respectively. If the hydrogen atom transverse relaxation time of the matrix filled with the first filler is less than that of the matrix filled with the second filler, the interfacial interaction between the first filler and the matrix is stronger than that between the second filler and the matrix.

[0013] Preferably, when the apparent crosslinking density is selected as the characteristic parameter, the apparent crosslinking densities of the matrix filled with the first filler and the matrix filled with the second filler are measured respectively. Or if the apparent crosslinking density of the matrix filled with the first filler is greater than that of the matrix filled with the second filler, the interfacial interaction between the first filler and the matrix is stronger than that between the second filler and the matrix.

[0014] Preferably, the matrix is a polymer material adhesive, and the filler is an inorganic salt or metal particles.

[0015] The beneficial effects of this solution are as follows:

[0016] Based on low-field nuclear magnetic resonance technology, the present invention has the characteristics of mature technology, simple operation and rapid experiment, and can obtain experimental results in a relatively short time. Specific embodiments

[0017] The following further describes in detail the implementation manners of this solution. Obviously, the described embodiments are only a part of the embodiments of this solution, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in this solution and the features in the embodiments can be combined with each other.

[0018] The terms "first", "second", etc. (if any) in the specification and claims are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments described herein can be implemented in an order other than that described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0019] It should be understood that the term "and / or" used herein is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone.

[0020] Research shows that the mechanical properties of composite solid propellants depend on the "weak link" among the filler, matrix, and filler / matrix interface. For current composite solid propellants, the internal damage of the propellant invariably starts from debonding at the filler / matrix interface and expands into macroscopic cracks. The filler / matrix interface is a major constraint on the improvement of the mechanical properties of the propellant. Therefore, how to quickly and accurately evaluate the role of the filler / matrix interface is of great significance for the improvement of the mechanical properties of composite solid propellants, the analysis of structural integrity, and the analysis of failure mechanisms.

[0021] At present, the contact angle method and the mechanical method are the main methods commonly used to evaluate the role of the filler / matrix interface. Generally, the contact angle method requires measuring the contact angles of the filler, matrix, and several different organic solvents separately, and then calculating the surface tension and adhesion work between the filler and the matrix. The experimental process is cumbersome and a large amount of organic solvents are used; the mechanical method is to obtain the parameters for evaluating the role of the filler / matrix interface through tensile curves and dynamic mechanical curves and calculate through corresponding models, such as the Pontrayagin kv value method, etc. This type of method is relatively complex to calculate.

[0022] The inventors of the present application provide a method for evaluating the role of the filler / matrix interface. The method includes:

[0023] 1) Prepare a non-filled binder matrix film A;

[0024] 2) Prepare a binder matrix film C filled with filler B;

[0025] 3) Respectively measure the transverse relaxation time T2 of hydrogen atoms or the apparent crosslinking density V of film A and film C by low-field nuclear magnetic resonance technology e ;

[0026] 4) Compare the transverse relaxation time T2 of Film A and Film C. If the transverse relaxation time T2(C) of the hydrogen atoms in Film C is less than T2(A) of Film A, then there is a strong interfacial interaction between Filler B and the binder matrix;

[0027] If the apparent crosslinking density V e (C) of Film C is greater than V e (A) of Film A, then there is a strong interfacial interaction between Filler B and the matrix.

[0028] In low-field nuclear magnetic resonance technology, the transverse relaxation time T2 of hydrogen atoms reflects the degree of restriction of hydrogen atom movement. Generally speaking, the smaller the transverse relaxation time T2, the more restricted the hydrogen atom movement. In the field of composite solid propellants, the binder is mostly a hydrogen-containing polymer material. When a solid filler is added to the binder, if there is a strong interfacial interaction between the solid filler and the binder, it will lead to restricted movement of hydrogen atoms at the interface. Reflected in low-field nuclear magnetic resonance technology, the transverse relaxation time T2 of hydrogen atoms will become smaller. Therefore, by comparing the transverse relaxation time T2 of hydrogen atoms, the interfacial interaction between the filler and the matrix can be effectively judged.

[0029] In low-field nuclear magnetic resonance technology, the apparent crosslinking density of the sample can be given by measuring the motion state signal of hydrogen atoms. The more restricted the movement of hydrogen atoms, the greater the apparent crosslinking density measured by low-field nuclear magnetic resonance. Therefore, when the interfacial interaction is stronger, the movement of hydrogen atoms in the matrix is more restricted, which will make the apparent crosslinking density measured by low-field nuclear magnetic resonance greater. So the apparent crosslinking density also reflects the strength of the filler / matrix interfacial interaction.

[0030] This method is an evaluation method for the filler / matrix interfacial interaction of composite solid propellants based on low-field nuclear magnetic resonance technology, which has the characteristics of mature technology, simple operation, and rapid experiment, and can obtain experimental results in a short time.

[0031] The following is an illustration of this application through specific examples.

[0032] Example 1

[0033] Prepare three simplified film specimens, and the basic composition of the specimens is shown in Table 1.

[0034] Table 1

[0035]

[0036] Use low-field nuclear magnetic resonance technology to test the three samples in Example 1 to obtain the transverse relaxation time T2 of their hydrogen atoms. The test results are shown in Table 2; at the same time, use the contact angle method to obtain the adhesion work measurement values between the HTPB binder and ammonium perchlorate and aluminum powder respectively. The test results are shown in Table 3.

[0037] Table 2

[0038]

[0039] Table 3

[0040]

[0041] As can be seen from Table 2, the transverse relaxation time T2 of hydrogen atoms in Specimen 2 and Specimen 3 is less than that in Specimen 1, and the apparent crosslinking density of Specimen 2 and Specimen 3 is greater than that in Specimen 1, indicating that ammonium perchlorate, aluminum powder and HTPB binder all have good interfacial effects. Moreover, the transverse relaxation time T2 of hydrogen atoms in Specimen 3 is less than that in Specimen 2, and the apparent crosslinking density is greater than that in Specimen 2, indicating that the interfacial effect between aluminum powder and HTPB binder is stronger than that between ammonium perchlorate and binder, which is consistent with the results in Table 3.

[0042] Obviously, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for evaluating the interfacial interaction of filler / matrix in composite solid propellants, characterized in that, The method includes: Based on the comparison of the characteristic parameters of the unfilled matrix and the matrix filled with fillers, or Based on the comparison of the characteristic parameters of the matrices filled with different fillers, Evaluating the interfacial interaction between the filler / matrix; The characteristic parameters include any one of the hydrogen atom transverse relaxation time and the apparent crosslinking density; When the hydrogen atom transverse relaxation time is selected as the characteristic parameter, the hydrogen atom transverse relaxation times of the unfilled matrix and the matrix filled with fillers are measured respectively. If the hydrogen atom transverse relaxation time of the matrix filled with fillers is less than that of the unfilled matrix, there is a strong interfacial interaction between the matrix filled with fillers and the filler; When the apparent crosslinking density is selected as the characteristic parameter, the apparent crosslinking densities of the unfilled matrix and the matrix filled with fillers are measured respectively. If the apparent crosslinking density of the matrix filled with fillers is greater than that of the unfilled matrix, there is a strong interfacial interaction between the matrix filled with fillers and the filler; When the hydrogen atom transverse relaxation time is selected as the characteristic parameter, the hydrogen atom transverse relaxation times of the matrix filled with the first filler and the matrix filled with the second filler are measured respectively. If the hydrogen atom transverse relaxation time of the matrix filled with the first filler is less than that of the matrix filled with the second filler, the interfacial interaction between the first filler and the matrix is stronger than that between the second filler and the matrix; When the apparent crosslinking density is selected as the characteristic parameter, the apparent crosslinking densities of the matrix filled with the first filler and the matrix filled with the second filler are measured respectively. Or if the apparent crosslinking density of the matrix filled with the first filler is greater than that of the matrix filled with the second filler, the interfacial interaction between the first filler and the matrix is stronger than that between the second filler and the matrix.

2. The evaluation method for the filler / matrix interfacial interaction of the composite solid propellant according to claim 1, wherein The matrix is a polymer material adhesive, and the filler is an inorganic salt or a metal particle.

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