Method for testing the degree of plasticization of propellant

Abstract

The application discloses a testing method for the plasticizing degree of gun propellant. The method comprises sampling during kneading and plasticizing, sample processing, testing, and confirmation of the plasticizing degree of the gun propellant. The application has good accuracy, simple operation, good reproducibility, and less safety hazards. The application can be applied to gun propellant product quality detection, gun propellant production equipment parameter debugging, and gun propellant plasticizing theory research.

Description

Technical Field

[0001] The invention belongs to the technical field of physical and chemical property detection and rheological property of propellants, and mainly relates to a method for characterizing the degree of plasticization of propellants during kneading. Background Art

[0002] Propellant, as the vital energy source propelling projectiles in barreled weapons, is an indispensable component. With the continuous advancement of industrial production technology, propellant manufacturing techniques have made significant progress. However, the production process still relies on the solvent-based process principles of Abel's era. Propellant primarily uses nitrocellulose as an energetic binder. Nitrocellulose molecular chains are semi-rigid and thermosetting. Furthermore, nitrocellulose with a nitrogen content of 12.6% has a melting point of approximately 617°C, a glass transition temperature of 173°C to 176°C, and a detonation temperature of 185°C, reaching its detonation point before reaching its melting point. Therefore, nitrocellulose cannot be converted to a viscous flow state by heating like conventional polymers for processing. Instead, organic solvents or plasticizers are required to dissolve and plasticize it, lowering its glass transition temperature and allowing it to flow and deform for easier molding.

[0003] The propellant plasticizing process is a key step in the solvent-based production process of propellants. The propellant plasticizing process ensures that the propellant material components are evenly mixed, the performance is stable, and the plasticity is enhanced.

[0004] However, at present, there is no stable and reliable data-based method for evaluating the degree of plasticization in the actual production process. Most judgments are made based on experience, resulting in insufficient performance stability of propellants and low yield rates. This not only reduces the production progress of weapon charges, but also causes huge waste of energetic materials. Therefore, studying the degree of plasticization of propellants and improving the quality of plasticization are difficult problems to be solved in propellant production. A method for evaluating the plasticization quality of propellants should be established to improve process parameters and improve the uniformity and performance stability of propellant products. The plasticization quality and uniformity of propellants have been determined by relying on experience, using visual observation and hand touch, which has exposed major problems: (1) poor accuracy. Because the "empirical method" is a semi-qualitative method, it has large human errors, and (2) poor reproducibility. The detection technique has many subjective factors and is difficult to promote and use. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for testing the plasticization degree of propellant.

[0006] The technical solution to achieve the purpose of the present invention is: a method for testing the plasticization degree of propellant, the method comprising: sampling during the kneading and plasticization process, sample processing, testing, and the plasticization degree of propellant Determine, including:

[0007] Step 1: Prepare the ingredients according to the propellant to be tested, add the materials and solvent into the kneader respectively, knead and plasticize, and select two samples from different parts of the plasticized propellant material;

[0008] Step 2: Use a press to press the two samples into propellant powder strips of the same shape to ensure consistent weight;

[0009] Step 3: Add the propellant powder strips into the capillary rheometer, test the shear viscosity of the two propellant powder strips respectively, and calculate the difference;

[0010] Step 4: Re-mix the propellant to be tested according to the step 1, add the material and solvent into the torque rheometer respectively, ensure the same speed as the kneader in step 1, and knead and plasticize. After the torque-time curve output by the torque rheometer is stable, select two samples from different parts of the plasticized propellant material.

[0011] Step 5: Repeat steps 2 and 3;

[0012] Step 6: Determine the degree of propellant plasticization Wherein, δ represents the shear viscosity difference of the sample in the kneader, and δ0 represents the shear viscosity difference of the sample in the torque rheometer.

[0013] Furthermore, the two samples were pressed into propellant strips of the same shape using a press, with the pressing temperature set to 45°C and the pressure set to 400 kN.

[0014] Furthermore, using a capillary die with an aspect ratio of 10:1, -1 The shear viscosity of the two samples was tested at a shear rate of 40°C.

[0015] Furthermore, during the kneading and plasticizing process, the temperature is no greater than 50°C.

[0016] Compared with the prior art, the beneficial effects of the present invention are: the present invention adopts a capillary rheometer combined with a torque rheometer, scientifically and rationally samples, and quantifies the degree of plasticization, making the degree of plasticization clearer and ensuring the accuracy of the test results; in addition, this test method has a short test time, simple operation and good reproducibility, and has fewer safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the torque-time curve and sampling timing in the torque rheometer.

[0018] Figure 2 4 is a histogram showing the viscosity and the absolute value of the viscosity difference δ of two samples in each embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to embodiments and drawings, but the present invention is not limited to these embodiments.

[0020] The present invention adopts a capillary rheometer combined with a torque rheometer, takes samples scientifically and rationally, and quantifies the degree of plasticization, making the degree of plasticization clearer and ensuring the accuracy of the test results. In addition, this test method has a short test time, simple operation, good reproducibility, and less safety hazards.

[0021] Kneader sampling method:

[0022] According to the requirements of the formula range, absorbent tablets were weighed as materials (Sichuan Luzhou 255 Factory), and anhydrous ethanol and acetone (mass ratio 1:1) were weighed as mixed solvents.

[0023] The absorbent tablets were evenly added to a horizontal kneader (Shanghai Red Star Chemical Machinery Factory). A mixed solvent of ethanol and acetone was evenly sprinkled on the surface of the absorbent tablets. The water circulation switch was turned on to allow circulating water to flow in. The kneader's operating temperature was maintained at 35°C. After sealing the kneader, kneading began at a speed of 45 rpm.

[0024] Two samples were quickly taken from two different locations in the propellant kneader. Sample 1 was taken near the kneader's stirring fins, while sample 2 was taken away from the kneader's stirring fins. Sample 1 was sheared and squeezed by the stirring fins, resulting in the largest difference between sample 1 and sample 2. This sample selection method is the most representative.

[0025] Torque rheometer sampling method:

[0026] According to the requirements of the formula range, absorbent tablets were weighed as materials (Sichuan Luzhou 255 Factory), and anhydrous ethanol and acetone (mass ratio 1:1) were weighed as mixed solvents.

[0027] The absorbent tablets were evenly added to a torque rheometer (Changchun Intelligent Instrument Equipment Co., Ltd.). A mixed solvent of ethanol and acetone was evenly sprinkled on the surface of the absorbent tablets. The water circulation switch was turned on to allow circulating water to flow in. The operating temperature of the torque rheometer was maintained at 35°C. Kneading was started at a speed of 45 rpm.

[0028] Two samples were quickly taken from two different locations of the propellant torque rheometer. Sample 3 was taken near the stirring fin of the torque rheometer, and sample 4 was taken away from the stirring fin. Sample 3 was sheared and squeezed by the stirring fin, and the difference between it and sample 4 was the largest. This sample selection method is the most representative.

[0029] Sample processing:

[0030] The samples were extruded into the copper mold of a press so that the test samples had the same shape. After extrusion, they were weighed on an electronic balance to ensure that each sample was 5 ± 0.2 g. After weighing, they were immediately wrapped with plastic wrap to prevent solvent volatilization and avoid experimental errors.

[0031] Test conditions:

[0032] The test was conducted using a capillary rheometer (Changchun Intelligent Instrument Equipment Co., Ltd.). The constant shear rate mode was used for the test. The temperature control system of the capillary rheometer was turned on, and the temperature of the barrel of the capillary rheometer was set to 40°C. The simulated material sample was added to the barrel and kept warm for 2 minutes until the sample temperature reached the set temperature. The die of the capillary rheometer was 10:1 (the diameter of the capillary die was 1mm). After setting the experimental parameters, the motor was loaded downward. When it came into contact with the drug, it was kept warm and pressurized for 2 minutes until the sample temperature reached the set temperature. Then the test was started, and the shear rate during the test was set to: 10s -1 After the material is extruded, observe the loading pressure-time curve and save the data after the curve stabilizes.

[0033] The shear viscosity of the above samples was tested, and the shear viscosity values ​​δ1 and δ2 of the kneader samples were obtained respectively, and the absolute value of the shear viscosity difference δ was calculated. The shear viscosity values ​​δ3 and δ4 of the torque rheometer samples were obtained respectively, and the absolute value of the shear viscosity difference δ0 was calculated to determine the plasticization degree of the propellant to be tested.

[0034] Example 1

[0035] After kneading the propellant material for 15 minutes, take it out and test the plasticization degree of the propellant material at this moment.

[0036] According to the propellant formula to be tested, ZY absorbent tablets (from Sichuan Luzhou 255 Factory) were weighed as the material. 33 g of anhydrous ethanol and 33 g of acetone (mass ratio 1:1) were weighed as the mixed solvent.

[0037] The absorbent tablets were evenly added to a horizontal kneader (Shanghai Red Star Chemical Machinery Factory). A mixed solvent of ethanol and acetone was evenly sprinkled on the surface of the absorbent tablets. The water circulation switch was turned on to allow circulating water to flow in. The kneader's operating temperature was maintained at 35°C. After sealing the kneader, kneading began, and the kneader speed was set to 45 rpm.

[0038] After the kneading process was carried out for 15 minutes, two samples were quickly taken out from two different parts of the propellant kneader, where sample 1 was taken near the stirring wing of the kneader, and sample 2 was taken away from the stirring wing of the kneader.

[0039] Following the same propellant charge ratio, 30 g of ZY absorber tablets (from Sichuan Luzhou 255 Factory) were weighed again. 3.3 g each of anhydrous ethanol and acetone (mass ratio 1:1) were weighed as a mixed solvent.

[0040] The absorbent tablets were evenly added to a torque rheometer (Changchun Intelligent Instrument Equipment Co., Ltd.). A mixed solvent of ethanol and acetone was evenly sprinkled on the surface of the absorbent tablets. The water circulation switch was turned on to allow circulating water to flow in. The operating temperature of the torque rheometer was maintained at 35°C. Kneading was started at a speed of 45 rpm.

[0041] At two different locations of the torque rheometer, when the torque-time curve of the torque rheometer is stable, quickly take out two samples (see Figure 1 ).

[0042] The four samples were extruded into the copper mold of a press to ensure that the test samples had the same shape. After extrusion, they were weighed on an electronic balance to ensure that each sample was 5 ± 0.2 g. After weighing, they were immediately wrapped with plastic wrap to prevent solvent volatilization and avoid experimental errors.

[0043] A capillary rheometer (Changchun Intelligent Instrument Equipment Co., Ltd.) was used to test the above samples. The constant shear rate mode was used for testing. The temperature control system of the capillary rheometer was turned on, and the temperature of the barrel of the capillary rheometer was set to 40°C. The simulated material sample was added to the barrel and kept warm for 2 minutes to allow the sample temperature to reach the set temperature. The die of the capillary rheometer was 10:1 (the diameter of the capillary die was 1mm). After setting the experimental parameters, the motor was loaded downward. When it came into contact with the drug, it was kept warm and pressurized for 2 minutes until the sample temperature reached the set temperature. Then the test was started. The shear rate during the test was set to: 10s -1 After the material is extruded, observe the loading pressure-time curve and save the data after the curve stabilizes.

[0044] The shear viscosities of two samples (sample 1 and sample 2) taken out from the kneader were 9726.1 Pa·s and 11925.6 Pa·s respectively. The absolute value of the difference in shear viscosity between the two samples was calculated to be 2199.5 Pa·s (see Figure 2 The shear viscosity standard values ​​of the samples (sample 3 and sample 4) taken out from the torque rheometer were 11222.6 Pa·s and 11386.2 Pa·s, and the absolute value of the difference in shear viscosity between the two samples, δ0, was 163.6 Pa·s.

[0045] Finally determine the degree of plasticization

[0046] Example 2

[0047] The same material ratio as in Example 1 was used, and the materials were kneaded for 45 minutes. The same steps as in Example 1 were used to test the degree of plasticization of the propellant material. The same test conditions as in Example 1 were adopted, wherein the shear viscosities of the two samples taken out of the kneader were 11204.5 Pa·s and 10028.5 Pa·s, respectively. The absolute value of the difference in shear viscosity between the two samples, δ, was calculated to be 1176 Pa·s. The standard values ​​of the shear viscosity of the samples taken from the torque rheometer were 11222.6 Pa·s and 11386.2 Pa·s (see Figure 2 ), the absolute value of the shear viscosity difference δ0 of the two samples is 163.6 Pa·s.

[0048] Calculate the plasticization degree of the propellant material after kneading for 45 minutes under this process condition

[0049] Example 3

[0050] The same material ratio as in Example 1 was used, and the materials were kneaded for 90 minutes. The same steps as in Example 1 were then used to test the plasticization degree of the propellant material after kneading for 90 minutes.

[0051] The same test conditions as in Example 1 were adopted. The shear viscosities of the two samples taken out of the kneader were 10444 Pa·s and 10677 Pa·s, respectively. The absolute value of the difference in shear viscosity between the two samples was calculated to be 273 Pa·s (see Figure 2 The standard values ​​of the shear viscosity of the samples taken from the torque rheometer are 11222.6 Pa·s and 11386.2 Pa·s, and the absolute value of the difference in shear viscosity between the two samples, δ0, is 163.6 Pa·s.

[0052] Calculate the plasticization degree of the propellant material after kneading for 90 minutes under this process condition

[0053] The above example calculates the plasticization degree of the propellant material after kneading for 15 minutes, 45 minutes, and 90 minutes. The values ​​are 6.92%, 12.2% and 37.5% respectively. It can be seen from the examples that during a certain stage of dissolution and plasticization of the propellant, the uniformity and plasticization degree of the propellant will continue to increase.

[0054] The above descriptions are merely examples of several embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with preferred embodiments, they are not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the present invention, make slight changes or modifications to the above-disclosed structures and technical contents to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention are still within the scope of the present invention.

Claims

1. A method for testing the plasticization degree of a propellant, characterized in that: The method specifically includes: Step 1: Prepare the ingredients according to the propellant to be tested, add the materials and solvent into the kneader respectively, knead and plasticize, and select two samples from different parts of the plasticized propellant material; Step 2: Use a press to press the two samples into propellant powder strips of the same shape to ensure consistent weight; Step 3: Add the propellant powder strips into the capillary rheometer, test the shear viscosity of the two propellant powder strips respectively, and calculate the difference; Step 4: Re-mix the propellant to be tested according to the step 1, add the material and solvent into the torque rheometer respectively, ensure the same speed as the kneader in step 1, and knead and plasticize. After the torque-time curve output by the torque rheometer is stable, select two samples from different parts of the plasticized propellant material. Step 5: Repeat steps 2 and 3; Step 6: Determine the degree of propellant plasticization ,in, represents the difference in shear viscosity of the sample in the kneader, Represents the difference in shear viscosity of the sample in the torque rheometer.

2. The method according to claim 1, wherein The two samples were pressed into propellant strips of the same shape using a press, with the pressing temperature set at 45°C and the pressure at 400 kN.

3. The method according to claim 1, wherein Using a capillary die with an aspect ratio of 10:1, the -1 The shear viscosity of the two samples was tested at a shear rate of 40°C.

4. The method according to claim 1, wherein During the kneading and plasticizing process, the temperature is not higher than 50°C.

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