The influence of the semtex matrix on the thermal behavior and decomposition kinetics of cyclic nitramines

The thermal behavior and decomposition kinetics of Semtex 10 polymeric matrix (Semtex) bonded PBXs containing RDX (1,3,5-trinitro 1,3,5-triazinane), HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX (cis-1,3,4,6- tetranitrooctahydroimidazo [4,5-d] imidazole), HNIW (2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane) have been investigated by means of nonisothermal TG and DSC techniques. It is shown that only a single decomposition process occurs for RDX-SE and HMX-SE whilst an obvious two-step process occurs for CL-20-SE and BCHMX-SE. The onset of the exotherms were observed at 210.6, 239.7, 279.2 and 229.4 °C with the peak maxima at 232.2, 249.4, 280.4 and 240.2 °C, and energy changes of 1808, 2140, 612 and 1757 J·g^-1 for RDX-SE, BCHMX-SE, HMX-SE and CL-20-SE, respectively. It has been found that the Semtex matrix has little influence on the activation energy distribution for RDX, BCHMX and e-CL-20. The activation energies for BCHMX-SE and CL-20-SE decomposition are almost independent of the degree of conversion, with mean values of 159.6 ±1.9 and 187.3 ±1.8 kJ·mol^-1. It has been proved that Semtex and Viton A are better binders than C4 and Formex for ε-CL-20 and RDX based PBXs in terms of their greater thermal stability, and Formex is a poor binder for BCHMX.