Integrated GC and tri-GPC methods for purity evaluation and molecular characterization of key organic ingredients in...

This study highlights the critical need to assess the purity of key organic ingredients in composite solid propellants (CSP) for satellite launch vehicles. Components such as Dioctyl Adipate (DOA), Toluene Diisocyanate (TDI), Phenyl-beta-naphthylamine (PBNA), Trimethylolpropane (TMP), Butanediol (BDO) and Hydroxyl-terminated Polybutadiene (HTPB) significantly impact propellant properties, necessitating stringent quality control. A unified Gas Chromatography (GC) method was developed for the rapid and reliable analysis of DOA, TDI, PBNA, TMP and BDO. Key parameters such as temperature programming and carrier gas flow rates were optimized and ensured resolution of peaks and impurity detection. The method demonstrated excellent linearity and repeatability, achieving low Relative Standard Deviation (RSD) values for retention times and peak areas. It was successfully applied across multiple batches and sources, accurately determining TDI isomer ratios and TMP-BDO mixture ratios in Ambi-link. For HTPB, a Triple Detection Gel Permeation Chromatography (GPC) method was established to analyse molecular weights, polydispersity index (PDI), intrinsic viscosity and molecular sizes. This approach enhanced analytical precision while reducing time and labour, offering deeper insights into polymer behaviour and its correlation with propellant properties. By integrating GC and GPC methodologies, this study provides a robust, efficient framework for evaluating CSP ingredients, minimizing hazardous chemical use and improving quality assurance. This advanced characterization approach contributes to optimizing solid rocket propellant formulations and improving their overall performance.