Microcellular Foaming of Cellulose Acetate Binder-based Combustible Objects by Supercritical CO2

Abstract

Microcellular combustible objects are based on crystalline explosives bonded in polymer binders for good heat resistance performance. The porous structures can be generated using supercritical CO2 as foaming agent. Due to their porous structures, they are distinguished by high burning rate and can be adjusted to manifold applications. In this paper, microcellular combustible objects, based on cellulose acetate (CA) bonded 1,3,5-Trinitrohexahydro-1,3,5-triazine (RDX), were performed by solvent method and then foamed by two-step foaming process. Scanning Electron Microscopy (SEM) was used to investigate the influencing factors on the inner porous structure in foaming process, and the results revealed that micropores generated from microcracks between RDX particles and CA matrix, and then developed into viable bubbles. Higher foaming temperature, higher saturation pressure and lower saturation temperature is conducive to growth of micropores. Closed vessel test was used to test the combustion behaviour of samples with 60%, 65% and 70% RDX. The results of closed vessel test indicated that the foamed structure reduced the burning time and the burning behaviours can be adjusted by varying RDX content and foaming conditions.