Optimal selection method for curing temperature and time of lining for solid propellant

Abstract

The invention relates to a method for determining the curing temperature and time of a lining for a solid propellant, and belongs to the technical field of characterization and performance evaluation methods of surface chemical properties of polymer composite materials. At least one of the problems that in the prior art, the lining curing process is difficult to quantitatively characterize, the surface property in the lining curing process is difficult to measure in situ, and the curing degree judgment depends on manpower and experience is solved. The invention provides a method which comprises the following steps: preparing a lining sample with a certain composition for a solid propellant, and representing the change of surface characteristic groups of the lining sample along with time and the dynamic characteristics of the curing process at a certain temperature through a sum frequency vibration spectrum technology, so as to determine the optimal curing temperature and time. According to the method, in-situ measurement of the lining curing process is realized, and the actual curing process is highly simulated / restored; curing process monitoring and process judgment are more accurate, and manual dependence is avoided; the method can be widely applied to determination / optimization of the curing temperature and time of the lining in similar scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of characterization and performance evaluation methods of surface chemical properties of polymer composite materials, and in particular to a method for optimizing the curing temperature and time of a liner for a solid propellant. Background Art

[0002] The combustion chamber of a case-bonded solid rocket motor typically consists of a propellant, a liner, an insulation layer, and a case. The liner acts as a bonding material, bonding the propellant to the insulation layer or case through interfacial chemical reactions and physical interactions. The interfacial adhesion between the liner and the propellant directly impacts the structural integrity and operational reliability of the solid rocket motor. To achieve excellent adhesion, the liner surface must possess sufficient reactive groups for reaction with the propellant and exhibit good surface adhesion, while also avoiding any negative impact on the propellant. Currently, the commonly used bonding process for propellant and liner bonding involves rotating the liner-coated motor at a constant temperature. Centrifugal force is used to uniformize the liner thickness, allowing it to reach a "semi-cured" state over a period of time. The liner is then vacuumed and loaded with propellant. The "semi-cured" state is primarily determined by finger pressure, relying on the technician's experience. This lack of accurate, stable, and unified quantitative methods significantly impacts the stability of the charge quality.

[0003] Curing time and temperature are important parameters in the liner curing process, and are of great significance for improving the charging process and enhancing the interfacial bonding performance. The surface properties of polymers are usually determined by the molecular structure of the outermost layers of their surface, which are only a few angstroms thick and have unique properties that are completely different from the bulk phase. For liner systems composed of multiple components, the curing process involves a huge transition from liquid phase to solid phase. Due to their own technical limitations, commonly used surface research methods are difficult to achieve quasi-surface depth to characterize the dynamic changes in the molecular structure of the liner surface, and their application scenarios are also limited. For example, attenuated total reflection Fourier transform infrared spectroscopy requires the probe to be pressed against the sample and cannot be used to measure viscous liner. The contact angle can obtain the wetting effect, acidity and alkalinity, surface energy, etc. of the material surface, but it cannot clearly determine the surface group composition. X-ray photoelectron spectroscopy can only provide information on the composition and chemical state of surface elements. Therefore, it is difficult to accurately obtain the curing process parameters. Summary of the Invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a preferred method for the curing temperature and time of the liner for solid propellant, so as to solve at least one of the problems of the prior art, namely, the difficulty in quantitatively characterizing the liner curing process, the difficulty in in-situ measurement of the surface properties of the liner during the curing process, and the reliance on manual labor and experience in determining the degree of curing.

[0005] In addition, the present invention solves many difficulties in applying sum frequency spectroscopy (SFG) to monitoring the lining curing process through process design, parameter optimization, etc.

[0006] The present invention discloses a method for determining the curing temperature and time of a liner for a solid propellant, which specifically comprises the following steps:

[0007] S1: Pre-treat and clean the sample pool;

[0008] S2: Add the single component of the lining layer to the sample cell, use the sum frequency vibration spectrometer, adjust the incident light polarization combination mode and pre-test parameters, and pre-test each component of the lining layer separately to determine the resonance peak position corresponding to the surface characteristic group of each component;

[0009] S3: Weigh each component according to the lining system formula ratio, mix and stir evenly, let it stand and then add it to the sample cell; adjust the parameters of the sum frequency vibration spectrometer according to the test results of S2, and in-situ test the surface state of the lining during the entire curing process at different temperatures to obtain the sum frequency vibration spectra of the lining during the entire curing process at different temperatures;

[0010] S4: Decoding the sum frequency vibration spectrum obtained in S3, and analyzing the changes in peak position and peak intensity to analyze the changes in the content of the groups represented and the kinetics of the curing reaction on the surface of the lining;

[0011] S5: Determine the optimal curing temperature and time of the lining system based on the analysis results of S4.

[0012] Specifically, the solid propellant lining layer is composed of hydroxypolybutadiene (HTPB) and toluene diisocyanate (TDI); the molar ratio of the two is 1:1.

[0013] Specifically, the specific process of step S1 is: soaking the polytetrafluoroethylene sample cell in piranha washing solution for half an hour, and then washing it multiple times with deionized water and water with a resistance of 18.2 MΩ.

[0014] Specifically, in steps S2 and S3, the thickness of the sample in the sample pool is 5 to 8 mm.

[0015] Specifically, the polarization combination mode of the incident light described in step S2 is: the polarization combinations of sum frequency light, visible light and infrared light are ssp, sps, and ppp respectively, that is, the sum frequency light, visible light and infrared light combinations with polarization directions of ssp, sps, and ppp are used in turn to perform spectral scanning (based on the principle of sum frequency vibration spectroscopy).

[0016] Specifically, the pre-test parameters in step S2 are: the infrared laser power at the sample is 6.7 mW, the visible laser power is 9 mW, and the spectrum acquisition time is 10 min.

[0017] Specifically, the in-situ test temperature range in step S3 is 40-90° C., the time interval is 5-10 minutes, and the signal acquisition time is 3-5 minutes.

[0018] Specifically, in step S3, the samples are mixed by mechanical stirring, and the sample cell is left to stand at room temperature for 15 to 30 minutes before the sum frequency spectrum test.

[0019] Specifically, in step S3, when the spectral peak intensity does not change significantly with time at a certain temperature, it is determined that the curing process is completed and the measurement at this temperature is stopped.

[0020] Specifically, in step S3, the surface level of the sample needs to be recalibrated before each measurement.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] 1. The present invention can realize contactless, in-situ and quantitative characterization of the lining curing process, and highly restores / simulates the real curing process of the lining. The principle of sum frequency vibration spectroscopy (SFG) technology is: a beam of visible light with a frequency of ω1 and a beam of infrared light with a frequency of ω2 act on the interface at the same time, generating a sum frequency signal with a frequency equal to the sum of the frequencies of the two beams of light (ω1+ω2). As a second-order nonlinear optical method, sum frequency vibration spectroscopy (SFG) has high interface selectivity and sensitivity to non-centrosymmetric medium surfaces, that is, only the molecules in the interface layer (the interface layer is usually one to several layers of molecules thick) contribute to the sum frequency signal. The required sample amount is very small, and suitable molecules can be selected in large quantities.

[0023] Sum frequency vibrational spectroscopy (SFG) is used to detect interactions between surface and interface molecules and determine the extent of chemical reactions. The magnitude of intermolecular interactions and the extent of reaction are determined by changes in the intensity and width of the detected spectral peaks. The degree of order in the interface molecular groups is quantitatively characterized to determine whether the interaction and chemical reaction between the interface molecules and other molecules is complete. The method provided by this invention is simple to operate and provides a theoretical, material, and technical basis for the selection of new molecules and the exploration of reaction conditions.

[0024] 2. The present invention overcomes the difficulties of complex lining components and phase change during the curing process by optimizing process steps and parameters, ensuring measurement accuracy.

[0025] In order to solve the problem of complex components of the liner to be tested, the single component was first tested to determine the characteristic peak position and width of different components, ensuring the rationality of the test parameters. It was determined that the spectrum of the sample to be tested under three different polarization combinations of ssp, ppp and sps was required. (For Example 1), the CH=CH vibration sensitive to reaction temperature was selected as the analysis object. Through the change of CH=CH vibration intensity, we found that the reaction time at three reaction temperatures was 72min, 62min and 42min respectively. At the same time, the change of vibration peak intensity over time at 70°C was more stable. Because the actual sample will undergo phase change before and after the chemical reaction is complete, the height and level of the sample to be tested will change. We re-optimized the height and level of the sample based on the position of the sample signal on the EMCCD chip, without replacing the sample cell, reducing operational disturbances, and ensuring the accuracy of the optical path through operations such as level correction.

[0026] 3. The preferred method provided by the present invention is free from reliance on manual labor and experience and is suitable for large-scale promotion. The bonding effect of adhesives with other agents and metals will change with changes in the reaction environment and reaction time. The appropriate curing time and the timing of subsequent combination with other agents are highly dependent on production experience. The present invention uses sum frequency spectroscopy to study and analyze the interfacial dynamics of the curing process of HTPB, understands the interfacial properties under different reaction conditions at the molecular level, determines the reaction conditions, and determines the appropriate curing time. Compared with manual judgment, it is more accurate and free from reliance on experience.

[0027] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0029] Figure 1 is the sum frequency vibration spectrum of hydroxyl-terminated polybutadiene (HTPB) in Example 1 of the present invention;

[0030] Figure 2 is the sum frequency vibration spectrum of toluene diisocyanate (TDI) in Example 1 of the present invention;

[0031] Figure 3The sum frequency spectra of the mixed sample of HTPB and TDI in Example 1 of the present invention are changed with time at temperatures of 60°C, 70°C, and 80°C;

[0032] Figure 4 The graphs of the CH2, C=C-CH2 and CH=CH vibration peak intensities versus reaction time for the mixed sample of HTPB and TDI in Example 1 of the present invention at temperatures of 60°C, 70°C and 80°C, respectively. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0034] Curing time and temperature are important parameters in the curing process of the liner, and are of great significance for improving the charging process and enhancing the interfacial bonding performance. The surface properties of polymers are usually determined by the molecular structure of the outermost layers of their surface, which are only a few angstroms thick and have unique properties that are completely different from the bulk phase. For liner systems composed of multiple components, the curing process involves a huge transition from liquid phase to solid phase. Due to their own technical limitations, commonly used surface research methods are difficult to achieve quasi-surface depth to characterize the dynamic changes in the molecular structure of the liner surface, and their application scenarios are also limited.

[0035] Sum frequency vibrational spectroscopy (SFG), a second-order nonlinear spectroscopic technique, exhibits quasi-monolayer interface sensitivity and selectivity, enabling the acquisition of rich information on interfacial molecular structure and orientation. When a tunable infrared laser beam and a fixed-wavelength visible laser beam are incident simultaneously and at the same point on the sample surface, a sum frequency signal light with a frequency equal to the sum of the two incident laser frequencies is generated in the reflected direction. When the infrared laser frequency resonates with the vibrational transitions of the sample's molecular groups, the sum frequency signal light is enhanced, resulting in a sum frequency vibrational spectrum. Interface molecules are differentially affected by the upper and lower phases, disrupting their central symmetry and generating a sum frequency vibrational spectrum. Internal molecules are isotropic, resulting in a zero sum frequency signal. Sum frequency spectroscopy can meticulously reveal important information such as interfacial molecular density, group orientation angles, and molecular chemical properties. It has been widely used to study various interfaces, including nanoparticle surfaces, metal surfaces, polymer surfaces, and ionic liquid surfaces, addressing fundamental issues in many catalytic, biological, and electrochemical systems.

[0036] To address the difficulties of quantitatively characterizing the lining curing process with existing technologies, the difficulty of in-situ measuring surface properties during the curing process, and the reliance on manual effort and experience to determine the degree of curing, the inventors have attempted to develop sum frequency spectroscopy (SFG), which has the potential to be applied to monitoring the lining curing process (e.g., it can be used for liquid-solid measurements to ensure in-situ measurements; it can also measure without contact with the sample). However, in order to realistically restore / simulate the lining curing process as much as possible, the following difficulties remain:

[0037] (1) The lining system is generally a mixed system. How to determine the appropriate test parameters to ensure accurate detection and judgment of the curing process?

[0038] (2) The lining curing process involves a phase transition from liquid to solid. How to ensure the stability and accuracy of the test results while ensuring in-situ measurement?

[0039] (3) How to reasonably output or process experimental data to intuitively display and characterize the curing process.

[0040] Through in-depth research, the present invention solves many difficulties in applying sum frequency spectroscopy (SFG) to monitor the lining curing process by means of process design and parameter optimization.

[0041] The present invention discloses a method for determining the curing temperature and time of a liner for a solid propellant, which specifically comprises the following steps:

[0042] S1: Pre-treat and clean the sample pool;

[0043] S2: Add the single component of the lining layer to the sample cell, use the sum frequency vibration spectrometer, adjust the incident light polarization combination mode and pre-test parameters, and pre-test each component of the lining layer separately to determine the resonance peak position corresponding to the surface characteristic group of each component;

[0044] S3: Weigh each component according to the lining system formula ratio, mix and stir evenly, let it stand and then add it to the sample cell; adjust the parameters of the sum frequency vibration spectrometer according to the test results of S2, and in-situ test the surface state of the lining during the entire curing process at different temperatures to obtain the sum frequency vibration spectra of the lining during the entire curing process at different temperatures;

[0045] S4: Decoding the sum frequency vibration spectrum obtained in S3, and analyzing the changes in peak position and peak intensity to analyze the changes in the content of the groups represented and the kinetics of the curing reaction on the surface of the lining;

[0046] S5: Determine the optimal curing temperature and time of the lining system based on the analysis results of S4.

[0047] Specifically, the above method is applicable to HTPB liner and NEPE liner.

[0048] Specifically, the solid propellant lining layer is composed of hydroxypolybutadiene (HTPB) and toluene diisocyanate (TDI); the molar ratio of the two is 1:1.

[0049] Hydroxyl-terminated polybutadiene (HTPB) and toluene diisocyanate (TDI) are the main components of the most widely used hydroxyl / isocyanate curing system. The reaction between them determines the basic content of the curing process of this system. The present invention uses this as a representative example to establish a method for determining / optimizing the main parameters of its curing process, which is also applicable to real-formulation lining systems.

[0050] Specifically, step S1 involves soaking the PTFE sample cell in piranha solution for half an hour, followed by multiple rinses with large amounts of deionized water and 18.2MΩ water. PTFE is a stable material that does not readily react with the sample being tested or the cleaning agent. This step cleans the sample cell to prevent interference from other impurities (especially organic impurities) during the measurement process.

[0051] Preferably, in steps S2 and S3, the thickness of the sample in the sample cell is 5 to 8 mm, which can meet the measurement requirements and prevent the scattered light generated by another interface at the bottom of the sample cell from interfering with the measurement.

[0052] Specifically, the polarization combination mode of the incident light described in step S2 is: the polarization combinations of sum frequency light, visible light and infrared light are ssp, sps, and ppp respectively, that is, the sum frequency light, visible light and infrared light combinations with polarization directions of ssp, sps, and ppp are used in sequence to perform spectral scanning (based on the principle of sum frequency vibration spectroscopy), and all spectra are normalized using the spectrum of the z-cut quartz crystal to obtain the resonant SFG-VS of the sample.

[0053] This polarization combination is achieved by controlling the polarization direction of light using a half-wave plate. Based on the principles of sum-frequency spectroscopy, the resulting three spectra can be used to quantitatively study the orientation angles of molecular groups at interfaces. Spectral normalization facilitates quantitative comparison of spectra, enabling monitoring of reaction progress.

[0054] Specifically, the pre-test parameters in step S2 are: the infrared laser power at the sample is 6.7 mW, the visible laser power is 9 mW, and the spectrum acquisition time is 10 min.

[0055] For example, the polarization combinations of sum frequency (SF), visible light (vis), and infrared (IR) light used in Example 1 are ssp, sps, and ppp. All spectra are normalized using the spectrum of a z-cut quartz crystal to obtain the resonant SFG-VS of the sample. The resulting spectral peaks are analyzed using a global fitting method and a Lorentzian shape function to obtain the peak position, peak intensity, and peak width of the sum frequency spectrum.

[0056] Specifically, the in-situ test temperature range in step S3 is 40-90° C., the time interval is 5-10 minutes, and the signal acquisition time is 3-5 minutes (duration).

[0057] Specifically, in step S3, the sample is mixed by mechanical stirring, and the sample cell is left to stand at room temperature for 15 to 30 minutes before the sum frequency spectrum test to ensure that the bubbles stirred in the sample to be tested dissipate, so as to avoid the floating or rupture of bubbles during the curing process affecting the curing process and measurement accuracy.

[0058] Specifically, after preheating the sample pool at the curing temperature for 5 minutes, add the configured lining sample to be tested. Preheating the sample pool in advance can reduce the influence of molecular interactions at low temperatures.

[0059] Specifically, the test parameter adjustment method in step S3 is:

[0060] The group to be characterized and the peak position are determined according to the pre-test results of step S2, and the wavelength range in step S3 is adjusted based on the above information.

[0061] For example, in Example 1, Figure 1 and Figure 2 These are the test results of HTPB and TDI (single component). According to the polarization selection rule of the spectrum, the spectral peaks are identified as follows: 2847, 2908 and 2993 cm in HTPB -1 The spectral peaks are derived from the CH symmetric stretching vibrations in CH2, C=C-CH2 and CH=CH groups; the peaks at 2921 and 2935 cm in TDI are derived from the CH symmetric stretching vibrations in CH2, C=C-CH2 and CH=CH groups respectively. -1 Originating from the symmetric and antisymmetric stretching vibrations of the CH3 group, 2864 cm -1 The peak at 2893cm is the overtone peak. -1 The small peak at 3000-3100cm is the interference result of the symmetric stretching vibration of CH3 and the overtone peak. -1 The broadband peak in the interval is the resonance peak produced by the CH vibration on the benzene ring. Therefore, CH2, C=C-CH2 and CH=CH were selected as the surface characteristic groups of this system, and the subsequent spectrum test range was 2700~3100cm -1 .

[0062] Specifically, in step S3, when the spectral peak intensity at a certain temperature shows no significant change over time, the curing process is determined to be complete, and the measurement at that temperature is stopped. The above characterization results indicate that the state of the surface layer has been essentially finalized, with no significant change in the corresponding spectral peak intensity.

[0063] Specifically, in step S3, the surface level of the sample needs to be recalibrated before each measurement to ensure the accuracy of the sum frequency signal optical path.

[0064] Exemplarily, the process can utilize a high-precision laser displacement sensor to detect height changes on the micrometer scale, determine the surface levelness by the level of the signal on the CCD, and perform level and height adjustments through a three-dimensional sample stage.

[0065] Specifically, the specific process of spectrum interpretation in step S4 is:

[0066] The obtained spectral peaks were fitted using a global fitting method and a Lorentz shape function to obtain the peak position, peak intensity, and peak width values ​​of the sum frequency spectrum. The fitting formula for the sum frequency vibration spectrum is:

[0067]

[0068] in, is the off-resonance polarizability, A q ,ω q and Γ q The amplitude, resonant frequency, and Lorentzian linewidth of the qth vibrational mode, respectively, are analyzed in conjunction with sum frequency vibrational spectroscopy theory. By analyzing changes in peak position and intensity, we can analyze changes in group content and the curing reaction kinetics. The above spectrum interpretation process is well-established in the art and will not be elaborated upon in this application.

[0069] Specifically, the specific process of step S5 is: comparing the effects of temperature and time on surface groups and kinetic processes, determining the curing reaction time at the temperature based on the process in which the peak intensity of the surface characteristic groups changes from drastic changes to stable over time, and then comparing the length of the curing time to determine the optimal curing temperature and time for the lining system.

[0070] Taking Example 1 as an example, Figure 3 It can be seen that the curing reaction intensity is the highest at 80℃, but the reaction process fluctuates strongly and the time to complete the curing is relatively long (e.g. Figure 4 When the temperature is 70°C, the reaction intensity is moderate, but the curing process is completed the earliest (as shown in the figure), and the optimal curing time (corresponding to 70°C) is between 39 and 62 minutes (a more accurate time segment can be obtained by reducing the sampling time interval).

[0071] The temperature and time optimization method provided by the present invention characterizes and evaluates the surface composition and changes of the lining through an optimized sum frequency vibration spectroscopy measurement method. The measurement process of this method is simple and convenient, the experimental results are intuitive and efficient, and the amount of information provided is rich, thereby providing an important basis and reference for interface design and interface bonding mechanism research, and has strong guiding significance and direct application value.

[0072] Example 1

[0073] The curing temperature and time of a hydroxy-terminated polybutadiene (HTPB) / toluene diisocyanate (TDI) system were determined. Before testing, the polytetrafluoroethylene (PTFE) sample cell was soaked in piranha solution for half an hour and then rinsed multiple times with copious amounts of deionized water and 18.2 MΩ water. Sum frequency spectrum (SFG) spectroscopy (VS) was performed using 10 ml of HTPB and 6 ml of TDI, respectively, with a sample thickness of approximately 5 mm. The sum frequency (SF), visible (vis), and infrared (IR) polarization combinations of ssp, sps, and ppp were used. The resonant SFG-VS of the sample was obtained using spectral normalization using a z-cut quartz crystal.

[0074] Figure 1 and Figure 2 These are the preliminary test results of HTPB and TDI. According to the polarization selection rule of the spectrum, the spectral peaks are identified as follows: 2847, 2908 and 2993 cm in HTPB -1 The spectral peaks are derived from the CH symmetric stretching vibrations in CH2, C=C-CH2 and CH=CH groups; the peaks at 2921 and 2935 cm in TDI are derived from the CH symmetric stretching vibrations in CH2, C=C-CH2 and CH=CH groups respectively. -1 Originating from the symmetric and antisymmetric stretching vibrations of the CH3 group, 2864 cm -1 The peak at 2893cm is the overtone peak. -1 The small peak at 3000-3100cm is the interference result of the symmetric stretching vibration of CH3 and the overtone peak. -1 The broadband peak in the interval is the resonance peak produced by the CH vibration on the benzene ring. Therefore, CH2, C=C-CH2 and CH=CH were selected as the surface characteristic groups of this system, and the subsequent spectrum test range was 2700-3100 cm -1 .

[0075] HTPB and TDI were mixed in a 1:1 molar ratio, mechanically stirred at different temperatures for 5 minutes, and then allowed to stand at room temperature for 20 minutes. The sample cell was preheated at 60°C, 70°C, and 80°C for 5 minutes before adding the prepared HTPB-TDI liner sample. At intervals of 10 minutes, the in-situ measurements of CH2, C=C-CH2, and CH=CH at 2700-3100 cm-1 were performed at 60°C, 70°C, and 80°C. -1 The sum frequency vibration spectrum within the range was collected for 3 minutes. The surface level of the sample was recalibrated for each test. When the peak intensity of the spectrum did not change significantly over time, the measurement of the temperature was stopped. The results are as follows: Figure 3As shown. Fitting the spectrum revealed that the vibration peak of HTPB was detected at the interface during the reaction, but there was no CH vibration peak of TDI. Therefore, it can be seen that the TDI molecules are not at the interface or the molecules are arranged parallel to the surface at the interface. Analysis of the vibration peak positions of HTPB at the interface during the reaction showed that the peak positions of CH2 and C=C-CH2 did not change; the CH=CH vibration peak positions were 2990, 2995 and 2986 cm at reaction temperatures of 60, 70 and 80°C, respectively. -1 , which reflects the intensity of the reaction between HTPB and TDI at different temperatures. The reaction between molecules is the strongest at 80℃.

[0076] The peak intensity of the above groups was plotted against time at reaction temperatures of 60°C, 70°C and 80°C, and the results are shown in Figure 2. Figure 4 As shown in the figure, at 70°C, the CH2, C=C-CH2, and CH=CH vibration peak intensities all decrease with increasing curing time before stabilizing. However, at the other two curing temperatures, the intensities of these group vibration peaks fluctuate dramatically. The CH=CH vibration is more sensitive to reaction temperature and can better reflect the progress of the curing reaction.

[0077] Comparing the changes in CH=CH vibration intensity, it was determined that the reaction completion time at 70°C was 39-62 minutes, the shortest reaction time. Therefore, the optimal curing temperature for this system is 70°C and the reaction time is 39-62 minutes.

[0078] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for determining the curing temperature and time of a liner for a solid propellant, characterized in that: The specific steps include: S1: Pre-treat and clean the sample pool; S2: Add the single component of the lining layer to the sample cell, use the sum frequency vibration spectrometer, adjust the incident light polarization combination mode and pre-test parameters, and pre-test each component of the lining layer separately to determine the resonance peak position corresponding to the surface characteristic group of each component; S3: Weigh each component according to the lining system formula ratio, mix and stir evenly, let it stand and then add it to the sample cell; adjust the parameters of the sum frequency vibration spectrometer according to the test results of S2, and in-situ test the surface state of the lining during the entire curing process at different temperatures to obtain the sum frequency vibration spectra of the lining during the entire curing process at different temperatures; S4: Decoding the sum frequency vibration spectrum obtained in S3, and analyzing the changes in peak position and peak intensity to analyze the changes in the content of the groups represented and the kinetics of the curing reaction on the surface of the lining; S5: Determine the optimal curing temperature and time of the lining system based on the analysis results of S4.

2. The determination method according to claim 1, wherein: The solid propellant lining layer is composed of hydroxy polybutadiene (HTPB) and toluene diisocyanate (TDI); the molar ratio of the two is 1:

1.

3. The determination method according to claim 1, wherein: The specific process of step S1 is: soaking the polytetrafluoroethylene sample cell in piranha washing solution for half an hour, and then washing it multiple times with deionized water and water with a resistance of 18.2 MΩ.

4. The determination method according to claim 1, wherein: In steps S2 and S3, the thickness of the sample in the sample pool is 5 to 8 mm.

5. The determination method according to claim 1, wherein: The polarization combination modes of the incident light in step S2 are: the polarization combinations of sum frequency light, visible light, and infrared light are ssp, sps, and ppp respectively.

6. The determination method according to claim 1, wherein: The pre-test parameters described in step S2 are: infrared laser power at the sample is 6.7 mW, visible laser power is 9 mW, and spectrum acquisition time is 10 min.

7. The determination method according to claim 1, characterized in that: The in-situ test temperature range of step S3 is 40-90° C., the time interval is 5-10 minutes, and the signal acquisition time is 3-5 minutes.

8. The determination method according to claim 1, wherein: In step S3, the samples are mixed by mechanical stirring, and the sample cell is left to stand at room temperature for 15 to 30 minutes before the sum frequency spectrum test.

9. The determination method according to claim 1, characterized in that: In step S3, when the spectral peak intensity does not change significantly with time at a certain temperature, it is determined that the curing process is completed and the measurement at this temperature is stopped.

10. The determination method according to claim 1, wherein: In step S3, the surface level of the sample needs to be recalibrated before each measurement.

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