Interactions between poly-(phthalazinone ether sulfone ketone) (PPESK) and TNT or TATB in polymer bonded explosives: a molecular dynamic simulation study

The glass transition temperature (T_g) and density of poly-(phthalazinone ether sulfone ketone) (PPESK A) were estimated by molecular dynamic (MD) simulation. A novel poly-(phthalazinone ether sulfone ketone) (PPESK B) was constructed by introducing nitrol and amini energetic groups into PPESK A, and T_g and density were also simulated for PPESK B. The estimated T_g values of PPESK A were very close to experimental results, while for PPESK B three estimated values differed by < 5 K. The interactions between explosives and polymer binders of polymer bonded explosives (PBXs) were simulated by MD. Comparison of the cohesive energy densities (CED) and solubility parameter (δ) values of PBXs, polymer binders, and mono-explosives indicate that, upon introducing polymer binders, the CED and δ values of PBXs decreased compared with those of corresponding mono-explosives. The binding energies (E_bind) imply that 2,4,6-trinitrotoluene-based PBXs are more stable than 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based PBXs. The mechanical properties, Young’s modulus E, shear modulus G, bulk modulus K, Poisson’s ratio γ and Cauchy pressure (C₁₂–C₄₄) of the PBXs were assessed. The rigidity of the PBXs was found to be lower than that of mono-explosives. All K/G values were positive, indicating that PBXs are flexible. Based on these mechanical properties results, PBXs using PPESK B as a binder are superior to those using PPESK A as a binder. Due to the low C₁₂–C₄₄ values of the PBXs, the ductility of the materials of the fracture surface is poorer, especially for TATB-based PBXs.