Rapid Quantification Of Component Content In The Production Process Of Single-base Propellants Using Near Infrared Spectroscopy

Single-base gun propellant is one soluble plastic powder based on nitrocellulose(NC)as the main body.It is mainly used as the energy source of small arms and artillery in our country.The production steps of single-base gun propellant are water driving,plasticizing,extrusion molding,cutting off,pre-drying,desensitization,lustering,first/second drying,etc.Water driving from NC by alcohol is the first step in the production of single-base gun propellant,water and alcohol content of dehydrated NC have great influence on the molding process of single-base gun propellant.The accuracy of stabilizer content determines the stability of single-base gun propellant in gelling process.Camphor content has influence on the degree of desensitization and ballistic trajectory of single-base gun propellant.However,the traditional analytical methods require samples being collected from production line and sent to lab for analysis by operators.That annlytical procedures consume a long time(>12h)and cannot afford real-time quality control on production line.Near infrared(NIR)analysis was proposed as a rapid,green and in-process alternative to solve that problem,the feasibility of useing NIR analysis to determine the content of composition during the production procedure of single-base gun propellant was investigated and stated in this paper for the first time.The contents and results of this investigation were detailed below:NIR analysis was used in the fast detection of component content of single-base gun propellant after water driving.The pretreatment method of SNV+lst derivative +smooth was chosen by comparing different spectral preprocessing methods.Partial Least-Squares(PLS)method was applied to set up linear mathematical model of water,ethanol and NC content.Spectral region were selected to construct the models by spectral analysis.The correlation coefficient of calibration(Rc2)and validation(Rp2)of the water model was 0.9970 and 0.9978 respectively,the Rc2 and Rp2 of ethanol model was 0.9835 and 0.9787 respectively,the Rc2 and Rp2 of NC model was 0.9860 and 0.9931 respectively.The average deviation of predicted values were less than 0.3%.Near infrared spectroscopy was applied for fast determination of diphenylamine(DPA)and N,N'-Dimethyl carbanilide(C2)content in single-base gun propellant.The optimization effect of the multi spectral pretreatment method was evaluated,and SNV+1st derivative ?smooth and SNV+ smooth were chosen for DPA and C2 repectively.The modeling wavenumber range was optimized by backward partial least squares(biPLS)and the spectral analysis results.Based on the optimization results of the modeling parameters,the quantitative models were established and verified.The Rc2 and Rp2 of DPA model were 0.9953 and 0.9874 respectively;the Rc2 and Rp2 of C2 model were 0.9823 and 0.9765 respectively.The average deviation of predicted values are less than 0.1%,and the change in evironment temperature has little influence on the model stability.NIR analysis was applied for fast determination of camphor content in desensitization process.The pretreatment method of MSC+1st derivative + smooth was chosen by comparing different spectral preprocessing methods.Spectral region were selected to construct the models by OPUS and spectral analysis.The Rc2 and Rp2 of the camphor model were 0.9723 and 0.9655 respectively,and the average deviation of predicted value was less than 0.1%.