The dependence of the non-linear creep properties of TATB-based polymer bonded explosives on the molecular structure of the polymer binder: (II) effects of the comonomer ratio in fluoropolymers

Abstract

1,3,5-triamino-2,4,6-trinitrobenzene (TATB) based polymer bonded explosives (PBXs), with three polymer binders containing different molecular structures, were studied by non-linear time dependent creep tests at different temperatures and stresses. Three fluoropolymers, i.e. F2311, F2313, and F2314 with molar ratios of comonomer vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE) of 1 : 1, 1 : 3, and 1 : 4 were chosen as polymer binders. The experimental results suggested that all of the materials showed temperature, stress and molecular structure sensitivity. With the decrease of temperature and stress, the creep resistance of the three TATB-based PBXs was improved with reduced creep strain, decreased steady-state creep strain rate, and prolonged creep failure time. Replacement of F2311 with F2313 in the binder system lead to a creep strain decrease and creep failure time rise. With further increasing of the CTFE content in fluoropolymers from 75% to 80%, the creep resistance performances were enhanced for TATB/F2314 composites under pressures from 1 to 9 MPa, compared with TATB/F2313 composites. The creep strain–time plots for TATB-based PBXs could be accurately fit using the six-element mechanical model. The long-term creep behaviors of TATB-based PBXs were predicted based on the time-temperature superposition (TTS) concept. In addition, the dynamic behaviors and mechanical properties of fluoropolymers and TATB-based PBXs were also studied and analyzed in detail.