Principal Component Analysis of FTIR Data to Accurately Assess the Real/Equivalent In‐Service‐Times of Homogenous Solid Propellant

Abstract

This study was devoted to setting up new methodologies for an accurate assessment of both real and equivalent in-service-times (RIST/EIST) of homogenous solid propellants (HSP) through a combination of principal component analysis (PCA) and Fourier transform infrared (FTIR) spectroscopy. Four double-base rocket propellants (DBRP) have been artificially aged at T = 338.65 K for 4 months with sampling every 20 days. FTIR showed that the homolytic scission of the O-NO 2 bonds and the hydrocarbon chains of the nitrate esters are the main processes occurring during the chemical decomposition. The scatter plot from PCA of FTIR spectra shows that over 93 % of the variance was described by the first principal component. Moreover, the loading plot designated the three characteristic FTIR bands from the nitro (NO 2 ) group as the most influenced by aging. A new PCA/FTIR experimental way was set to accurately assess the RIST of HSPs. The relative deviation associated with the RIST evaluated by the present procedure and those from the PCA/VST experimental way, recently developed, was found to range from 4.0 % to 6.7 %. Subsequently, a PCA/FTIR prediction model of the EIST is established. The predictions present a relative deviation of less than 7.1 % compared to the recent PCA/VST model. The accuracy of the model was further confirmed using similar DBRPs artificially aged for 6, 8, 10, and 12 months. The relative variation between the RIST provided by the PCA/FTIR procedure and the prediction model was found less than 5 %, thus confirming the highest accuracy of such combination.

Hygroscopicity of nitrocellulose with different nitrogen content

“…The strong characteristic absorption peak at 1633 cm −1 and 1273 cm −1 were related to the asymmetric and symmetric stretching vibrations of the ‐NO 2 [38, 39]. The characteristic absorption peak at 826 cm −1 , 747 cm −1 and 676 cm −1 can be attributed to the scissor vibration, asymmetric deformation, and symmetrical deformation of the ‐O‐NO 2 [39, 40]. The stretching vibration peak of the ‐CH bonds appeared at about 2909 cm −1 for NC [40, 41].…”

“…The characteristic absorption peak at 826 cm −1 , 747 cm −1 and 676 cm −1 can be attributed to the scissor vibration, asymmetric deformation, and symmetrical deformation of the ‐O‐NO 2 [39, 40]. The stretching vibration peak of the ‐CH bonds appeared at about 2909 cm −1 for NC [40, 41]. The weak characteristic absorption peak at about 3581 cm −1 was attributed to the stretching vibration of the linked −OH in the NC [40], and the intensity of characteristic peaks decreases with the increase of nitrogen content.…”

“…The stretching vibration peak of the ‐CH bonds appeared at about 2909 cm −1 for NC [40, 41]. The weak characteristic absorption peak at about 3581 cm −1 was attributed to the stretching vibration of the linked −OH in the NC [40], and the intensity of characteristic peaks decreases with the increase of nitrogen content. This indicated that the interaction force between NC molecules was weakened with the increase of nitrogen content, and the ability to form hydrogen bonds was also weakened as a result.…”

“…The stretching vibration peak of the -CH bonds appeared at about 2909 cm À 1 for NC [40,41]. The weak characteristic absorption peak at about 3581 cm À 1 was attributed to the stretching vibration of the linked À OH in the NC [40],…”

Comparative study on the rheological properties of cellulose acetate and double‐base propellant

“…Table 4 shows that the consistency coefficient of CA and DP decreases with the increase of temperature, which confirms the analysis of the influence of temperature on rheological property. And the consistency coefficient of CA at 55 °C was 41.56 % lower than that at 35 °C, and the consistency coefficient of DP at 51 °C was T A B L E 3 The bands assignments of CA and DP [22][23][24][25][26]. 13.03 % lower than that at 39 °C.…”