Method for rapidly detecting content of diphenylamine in multi-model single-base propellant

Abstract

The invention provides a method for rapidly analyzing the content of diphenylamine in a multi-model single-base propellant. The method comprises the following steps: step 1, selecting an original modeling sample; step 2, preparing a modeling sample; step 3, pretreatment of a modeling sample; 4, spectrum collection and obtaining of a diphenylamine content standard value; 5, establishing a sharing analysis model; and 6, determining the content of diphenylamine in the to-be-detected sample. According to the invention, a near infrared spectroscopic analysis model for the content of diphenylamine in the single-base propellant shared by multiple models is established, the content of diphenylamine in the single-base propellant shared by multiple models can be rapidly detected through the model, the detection work of one sample can be completed within 5 minutes, the measurement error is less than 0.1%, and the detection method is rapid and accurate.

Description

Technical Field

[0001] The invention belongs to the technical field of gunpowder detection, relates to single-base propellants, and specifically relates to a method for quickly detecting diphenylamine content in multi-model single-base propellants. Background Art

[0002] Diphenylamine is the most commonly used stabilizer in the production of single-base propellants. It can neutralize the nitrogen dioxide produced by the decomposition of nitrocellulose and prevent the autocatalytic effect of nitrogen dioxide on the decomposition of nitrocellulose, so as to ensure the chemical stability of single-base propellants and the safety of long-term storage. The content of diphenylamine must strictly meet the requirements of product technical performance. If the content is too high or too low, the stability may not meet the use requirements.

[0003] Single-base propellants are commonly used in bullets, grenades, anti-armor ammunition and anti-aircraft gun elastic propellant charges. They have the characteristics of fast burning rate, high charge density and low ablativeness. The evaluation of the stability of gunpowder charges is a necessary and crucial link in the production and storage process of gunpowder charges. Stability is one of the important indicators for the environmental adaptability assessment of weapons and ammunition, and it is also an important quality characteristic. The evaluation of the stability of gunpowder charges is mainly based on the change in the diphenylamine content over the storage time. Therefore, in the production process of single-base gunpowder and the long storage process of ammunition, the accurate and rapid detection of diphenylamine in single-base propellants is of great significance to product quality and charge stability evaluation.

[0004] At present, the determination methods of diphenylamine content mainly adopt chemical method and gas chromatography. The chemical method is a classic analysis method with many operation steps and large human errors. Gas chromatography also requires sample pretreatment, using a large amount of solvent to extract and separate the propellant, and then using chromatography for analysis. The overall analysis time is long and requires high professionalism of the testers. Therefore, the production of single-base propellants, gunpowder charging and stability evaluation of ammunition storage processes are in urgent need of a simple, accurate and fast analysis technology for diphenylamine content.

[0005] With the development of advanced spectral technology, the feasibility of using near-infrared spectroscopy to detect the content of diphenylamine in single-base propellants has been reported. For example, Zhou Shuai, Wang Zhiqiang and others from Nanjing University of Science and Technology studied a method for detecting the content of diphenylamine in a single-base propellant during the production process of a single-base propellant. They used chemometric methods to establish an analytical model between the content of diphenylamine and the near-infrared spectral data of a single-base propellant, and explored the feasibility of using near-infrared spectroscopy to quickly detect the content of diphenylamine in a single-base propellant. Once the near-infrared spectroscopy technology model is built, it is simple and fast to use for detection, and it is an ideal detection technology. However, we know that there are many types of single-base propellants used for various ammunition charges. Although the composition of different types of single-base propellants is similar, the main body is composed of nitrocellulose and diphenylamine, their external dimensions are completely different, and the particle size and density are very different. Because the material chemical properties of the sample, such as particle size, particle shape, composition, density, etc., will affect its near-infrared spectrum, generally one sample is used to establish an analytical model. The establishment of a mature, stable and reliable near-infrared analysis model usually costs a lot of manpower, material resources and financial resources. Therefore, when using near-infrared spectroscopy technology for a wide variety of single-base propellants, the difficulty is that many models need to be established, which requires too much investment and is not convenient for quality management. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for rapid detection of diphenylamine content in multiple types of single-base propellants, so as to solve the technical problems of high cost and large investment caused by the need to establish different analysis models when using near-infrared analysis methods for the diphenylamine content in different types of single-base propellants in the prior art.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0008] A method for rapidly analyzing the content of diphenylamine in multi-type single-base propellants, the method comprising the following steps:

[0009] Step 1: Selection of original modeling samples:

[0010] Multiple types of single-base propellant production samples including the type of sample to be tested are selected. In each type, multiple single-base propellant production samples with different storage periods are selected as original samples for modeling the single-base propellant.

[0011] Step 2: Preparation of modeling samples:

[0012] The modeling sample obtained in step 1 is prepared by using the thermal accelerated aging method.

[0013] Step 3: Preprocessing of modeling samples:

[0014] The modeling sample prepared in step 2 is crushed in a crusher to obtain a pre-treated modeling sample.

[0015] Step 4: Spectrum acquisition and acquisition of diphenylamine content standard value:

[0016] The pre-treated modeling samples obtained in step three are scanned by near-infrared diffuse reflectance spectrum to obtain a near-infrared spectrum set of the modeling sample set.

[0017] The standard value of the diphenylamine content in the pretreated modeling samples obtained in step three is determined by gas chromatography, and the standard value of the diphenylamine content in all the pretreated modeling samples obtained in step three is used as the standard value database of the modeling sample set.

[0018] Step 5: Establishment of shared analysis model:

[0019] Using chemometric methods, the near-infrared spectrum set of the modeling sample set obtained in step 4 is associated with the standard value database to establish a shared analysis model.

[0020] Step 6, determination of diphenylamine content in the sample to be tested:

[0021] The shared analysis model obtained in step five is used to determine the diphenylamine content in the test samples of various types of single-base propellants.

[0022] The present invention also has the following technical features:

[0023] In step one, the length range of the various types of medicines covers 2mm to 20mm, and the outer diameter range of the medicines covers 2mm to 15mm; for each type, at least 10 single-base propellant production samples with a storage period are selected.

[0024] In step 2, the oven temperature of the heat accelerated aging method is selected to be 85° C., and the aging times are 0 days, 5 days, 15 days and 25 days, respectively, to obtain modeling samples and form a modeling sample set.

[0025] In step 2, in the modeling sample set, the diphenylamine content ranges from 1.5% to 0.8%; the diphenylamine content range includes the diphenylamine content in the sample to be tested, and the diphenylamine content of the modeling sample is uniformly distributed within the diphenylamine content range.

[0026] In step three, the maximum particle size after the crushing pretreatment is close to 5 mm. For modeling samples with a length and particle size close to 5 mm or less than 5 mm, no crushing treatment is required, which is the pretreated modeling sample.

[0027] In step 4, the conditions for scanning the near-infrared diffuse reflectance spectrum are: the wavelength range includes 6102cm -1 ~5446cm-1 and 4751cm -1 ~4424cm -1 , resolution better than or equal to 8cm -1 .

[0028] Compared with the prior art, the present invention has the following technical effects:

[0029] (I) The present invention establishes a near-infrared spectroscopy analysis model for the diphenylamine content in single-base propellants that is shared by multiple models. The model can be used to quickly detect the diphenylamine content in multiple models of single-base propellants. The detection of a sample can be completed within 5 minutes, and the measurement error is less than 0.1%. The detection method is fast and accurate.

[0030] (II) In the detection process of the present invention, the sample only needs to be simply crushed, and there are not many requirements for the particle size of the crushing. Then, a near-infrared spectrum scan is performed. The temperature of the sample in contact with the sample during the scanning is room temperature, and there is no need for complex sample pretreatment. The detection process is safe, non-destructive, and simple to operate.

[0031] (III) The pulverizer and near-infrared spectrometer used in the method of the present invention are small in size and suitable for rapid detection in isolation rooms in remote places such as production sites and storage warehouses, thereby improving production efficiency and ensuring product safety.

[0032] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0033] It should be noted that, unless otherwise specified, all raw materials and reagents in the present invention are raw materials and reagents known in the prior art and can be obtained from commercial channels. All test methods in the present invention are conventional methods unless otherwise specified.

[0034] With the development of explosive technology, the formulation and process technology of new propellants are constantly improving. The shape and size of single-base propellants are important factors affecting the ballistic performance of gunpowder. In order to meet the requirements of different weapons for the shape and size of projectiles, propellants are made into spheres, sheets, strips, rings, granules, tubes and plum blossoms. From the number of internal holes, there are no holes, single holes and multiple holes. Usually, different types of single-base propellants have different sizes and shapes. Although the main components are basically the same, they are nitrocellulose and diphenylamine. However, when using near-infrared spectroscopy analysis methods, everyone follows conventional technical ideas to establish an analysis model for one sample. The cost of establishing the model is high, and the scope of application of the model is very narrow, which is not suitable for the application and promotion of near-infrared spectroscopy technology in the industry.

[0035] In order to solve the problems of high cost and difficulty in promotion caused by the need to establish a near-infrared analysis model for one type of single-base propellant, the present invention solves the problem of application and promotion through a method for establishing a near-infrared shared analysis model for diphenylamine content in multiple types of single-base propellants.

[0036] Based on near-infrared spectroscopy technology, fast, simple, safe and high-precision detection can be achieved. The design idea of ​​the present invention is to use a shared near-infrared spectroscopy analysis model to realize the rapid detection of diphenylamine content in various types of single-base propellants. The core of this technology is to establish a shared near-infrared spectroscopy analysis model for single-base propellants. The so-called shared near-infrared analysis model is the partial least squares method between the spectrum of the sample set established by chemometric methods and the standard value. This algorithm is applicable to various types of single-base propellant samples.

[0037] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0038] Embodiment 1:

[0039] This embodiment provides a method for quickly analyzing the content of diphenylamine in multi-type single-base propellants, the method comprising the following steps:

[0040] Step 1: Selection of original modeling samples:

[0041] Production samples of single-base propellants for guns and bullets and samples with different storage periods were selected, including 11 single-base propellant samples of different models, including 15 / 7, 13 / 7, 4 / 1, and 4 / 7. The size range of the samples was as follows: the sample length ranged from 1mm to 35mm, and the outer diameter of the sample covered a range of 1mm to 18mm.

[0042] Step 2: Preparation of modeling samples:

[0043] The 10 modeling samples of the single-base propellant obtained in step 1 were prepared by thermal accelerated aging method, the oven temperature was selected to be 85°C, the aging time was 0 day (modeling sample original), 5 days, 15 days, and 25 days, and the modeling sample original and the designed and prepared samples with different aging times were used as a modeling sample set. The diphenylamine content in the modeling sample set of the single-base propellant covers a range of 1.68% to 0.75%, and the diphenylamine content in the modeling sample is uniformly distributed within the diphenylamine content range.

[0044] Step 3: Preprocessing of modeling samples:

[0045] The modeling sample prepared in step 2 is crushed in a crusher. The maximum particle size after crushing is close to 5 mm. For modeling samples with a length and particle size close to 5 mm or less than 5 mm, no pretreatment is required. The pretreated sample and the sample that does not need pretreatment are combined to obtain the pretreated modeling sample.

[0046] Step 4: Spectrum acquisition and acquisition of diphenylamine content standard value:

[0047] The pre-treated modeling samples obtained in step three are scanned by near-infrared diffuse reflectance spectrum to obtain a near-infrared spectrum set of the modeling sample set.

[0048] Specifically, in this embodiment, the MPA Fourier transform near-infrared spectrometer of the German BRUKER company was selected, preheated for 0.5 hours, and the instrument resolution was set to 8 cm -1 , spectral range 12500cm -1 ~4000cm -1 , take 5g of sample into a sample cup with a diameter of 5cm and a thickness of more than 2cm, and collect the spectrum in diffuse reflectance mode. Each sample is measured 3 times, and each spectrum line is scanned 64 times.

[0049] The standard value of diphenylamine content in the pretreated modeling samples obtained in step three is determined by gas chromatography, and the standard value is accurate to 0.01%; the standard value of diphenylamine content in all pretreated modeling samples obtained in step three is used as the standard value database of the modeling sample set.

[0050] Step 5: Establishment of shared analysis model:

[0051] Using chemometric methods, the near-infrared spectrum set of the modeling sample set obtained in step 4 is associated with the standard value database to establish a shared analysis model.

[0052] In this embodiment, the establishment process of the shared analysis model includes the preprocessing of spectral data and the establishment of a correction model. The spectral data preprocessing method includes one or more combinations of spectral data centralization, smoothing, multivariate scatter correction (MSC), vector normalization (SNV), minimum-maximum normalization, first-order derivative, second-order derivative, etc. After the sample set spectral data is preprocessed, the partial least squares method (PLS) is used to associate it with the standard value of its diphenylamine content to establish a correction model. The analysis model is established by optimizing the conditions such as the diphenylamine content range, spectral quantitative range, and spectral preprocessing method in the single-base propellant sample set.

[0053] The optimization results show that the minimum distribution range of diphenylamine content in the sample set is between 1.5% and 0.8%, which includes the diphenylamine content range of the sample to be tested, and the samples are evenly distributed within the range. If the diphenylamine content in the sample set is too high, the sample is very scarce, and if the diphenylamine content is too low, the safety of the sample cannot be well guaranteed. The optimal spectral quantitative range is 6102cm -1 ~4424cm -1 The best combination of preprocessing methods is data centering + SNV + first-order derivative; the optimal parameters of the analysis model built under the best conditions are shown in Table 1. The determination coefficient (R 2 ) is 0.97(R 2 The closer it is to 1, the better the linear relationship between the model's predicted value and the standard value), the root mean square error (RMSECV) between the model's predicted value and the standard value is 0.05% (the smaller the RMSECV, the smaller the model's error), and the number of main factors is 7. It can be seen that the constructed model has good linearity and high accuracy.

[0054] Table 1 Conditions and parameters of the shared analysis model

[0055] Diphenylamine content range of sample set 1.68％～0.75％ Spectral quantitative range <![CDATA[6102cm -1 ~4424cm -1 ]]> Preprocessing methods Data centering + SNV + first-order derivative <![CDATA[R 2 ]]> 0.97 Number of principal factors 7 RMSECV 0.05％

[0056] Step 6, determination of diphenylamine content in the sample to be tested:

[0057] The shared analysis model obtained in step five is used to determine the diphenylamine content in the test samples of various types of single-base propellants.

[0058] Specifically, in this embodiment, 9 samples of 3 different types were drawn from the production line, and the diphenylamine content was determined using this model; at the same time, gas chromatography was also used for determination. The results of the two methods are shown in Table 2.

[0059] Table 2 Detection results of diphenylamine content in 9 samples

[0060] Sample No. Gas chromatography / % Near infrared spectroscopy / % Difference / % 1 1.71 1.66 -0.05 2 1.71 1.65 -0.06 3 1.68 1.64 -0.04 4 1.58 1.56 -0.02 5 1.55 1.51 -0.04 6 1.54 1.63 0.09 7 1.63 1.66 0.03 8 1.62 1.68 0.06 9 1.65 1.68 0.03

[0061] Embodiment 2:

[0062] This embodiment provides a method for quickly analyzing the content of diphenylamine in multi-type single-base propellants, the method comprising the following steps:

[0063] Step 1: Selection of original modeling samples:

[0064] Production samples of single-base propellants for guns and bullets and samples with different storage periods were selected. 13 samples of single-base propellants of different types, including 6 / 17, 5 / 7, 13 / 7, and 9 / 7, were selected. The size range of the samples was as follows: the sample length covered a range of 1mm to 35mm, and the outer diameter covered a range of 2mm to 20mm.

[0065] Step 2: Preparation of modeling samples:

[0066] The 13 single-base propellant modeling samples obtained in step 1 were prepared by thermal accelerated aging method, the oven temperature was selected to be 85°C, the aging time was 0 day (modeling sample original sample), 5, 15, and 25 days, and the original sample and the designed and prepared samples with different aging times were used as a modeling sample set. The diphenylamine content in the modeling sample set of the single-base propellant covers a range of 1.78% to 0.69%, and the diphenylamine content in the modeling sample is uniformly distributed within the diphenylamine content range.

[0067] Step 3: Preprocessing of modeling samples:

[0068] Same as step 3 of Example 1.

[0069] Step 4: Spectrum acquisition and acquisition of diphenylamine content standard value:

[0070] Same as step 4 of Example 1.

[0071] Step 5: Establishment of shared analysis model:

[0072] Same as step 5 of Example 1.

[0073] Step 6, determination of diphenylamine content in the sample to be tested:

[0074] The shared analysis model obtained in step five is used to determine the diphenylamine content in the test samples of various types of single-base propellants.

[0075] Specifically, in this embodiment, 9 samples of 3 different types were drawn from the production line, and the diphenylamine content was determined using this model; at the same time, gas chromatography was also used for determination. The results of the two methods are shown in Table 3.

[0076] Table 3 Detection results of diphenylamine content in 9 samples

[0077] Sample No. Gas chromatography / % Near infrared spectroscopy / % Difference / % 1 1.61 1.67 0.06 2 1.65 1.66 0.01 3 1.6 1.65 0.05 4 1.41 1.47 0.06 5 1.52 1.47 -0.05 6 1.44 1.45 0.01 7 1.09 1.17 0.08 8 1.19 1.15 -0.04 9 1.08 1.14 0.06

Claims

1. A method for rapid analysis of diphenylamine content in multi-type single-base propellants, the method comprising the following steps: Step 1: Selection of original modeling samples: Selecting multiple types of single-base propellant production samples including the type of the sample to be tested, and in each type, selecting multiple single-base propellant production samples with different storage periods as original samples of the single-base propellant modeling; Features: Step 2: Preparation of modeling samples: The modeling sample obtained in step 1 is prepared by using a thermal accelerated aging method; Step 3: Preprocessing of modeling samples: The modeling sample prepared in step 2 is crushed in a crusher to obtain a pre-treated modeling sample; Step 4: Spectrum acquisition and acquisition of diphenylamine content standard value: Scanning the pre-treated modeling samples obtained in step 3 with near-infrared diffuse reflectance spectra to obtain a near-infrared spectrum set of the modeling sample set; Determine the standard value of the diphenylamine content in the pretreated modeling samples obtained in step 3 by gas chromatography, and use the standard value of the diphenylamine content in all the pretreated modeling samples obtained in step 3 as the standard value database of the modeling sample set; Step 5: Establishment of shared analysis model: Using a chemometric method, the near infrared spectrum set of the modeling sample set obtained in step 4 is associated with the standard value database to establish a shared analysis model; Step 6, determination of diphenylamine content in the sample to be tested: The shared analysis model obtained in step five is used to determine the diphenylamine content in the test samples of various types of single-base propellants.

2. The method for rapid analysis of diphenylamine content in multi-type single-base propellants as claimed in claim 1, characterized in that: In step one, the length range of the various types of medicines covers 2mm to 20mm, and the outer diameter range of the medicines covers 2mm to 15mm; for each type, at least 10 single-base propellant production samples with a storage period are selected.

3. The method for rapid analysis of diphenylamine content in multi-type single-base propellants as claimed in claim 1, characterized in that: In step 2, the oven temperature of the heat accelerated aging method is selected to be 85° C., and the aging times are 0 days, 5 days, 15 days and 25 days, respectively, to obtain modeling samples and form a modeling sample set.

4. The method for rapid analysis of diphenylamine content in multi-type single-base propellants as claimed in claim 3, characterized in that: In step 2, in the modeling sample set, the diphenylamine content ranges from 1.5% to 0.8%; the diphenylamine content range includes the diphenylamine content in the sample to be tested, and the diphenylamine content of the modeling sample is uniformly distributed within the diphenylamine content range.

5. The method for rapid analysis of diphenylamine content in multi-type single-base propellants as claimed in claim 1, characterized in that: In step three, the maximum particle size after the crushing pretreatment is close to 5 mm. For modeling samples with a length and particle size close to 5 mm or less than 5 mm, no crushing treatment is required, which is the pretreated modeling sample.

6. The method for rapid analysis of diphenylamine content in multi-type single-base propellants as claimed in claim 1, characterized in that: In step 4, the conditions for scanning the near-infrared diffuse reflectance spectrum are: the wavelength range includes 6102cm -1 ~5446cm -1 and 4751cm -1 ~4424cm -1 , resolution better than or equal to 8cm -1 .