A glycidyl azide (GAP)-based polyurethane-urea (PUU) modifier used in the 1,3,5-trinitrotoluene (TNT)-based composite explosive was investigated by molecular simulation. Inter-molecular interactions were investigated using quantum chemistry calculation on the dimer of TNT and GAP-PUU, and attractive forces were found between the two molecules. The cohesive energy densities and the solubility parameters were obtained through molecular dynamics simulations combined with thermodynamic calculations on the TNT and GAP-PUU amorphous cell models, and the miscibility of the modifier in molten TNT was predicted to be good. The interaction energies and the mechanical properties were then obtained by molecular simulations and mechanical calculations on the solid-phase models of the GAP-PUU with TNT along three crystalline directions, and an improvement in the mechanical properties was predicted.

2,4-Dinitroanisole (DNAN) has excellent properties as a replacement for 1,3,5-trinitrotoluene (TNT) in melt-cast explosives, and the polymeric modifier used is critical to the mechanical modification of the DNAN/RDX energetic composite. In our research, the typical polymeric modifier acrolein-pentaerythritol resin (APER) was successfully added experimentally to the DNAN/RDX system, and the effects of interfacial interactions on the mechanical properties of these polymers in reinforcing the DNAN/RDX energetic composites were investigated by molecular dynamics simulations, scanning electron microscopy (SEM) and mechanical testing. The results showed that strong attractive interactions exist between the polymer and the explosives, wherein van der Waals forces were found to play the main role. The morphological micro-images also showed tight binding between the polymer/explosive interfaces, which supported the calculated strong interfacial interactions. The mechanical tests confirmed that adding the polymers can obviously reinforce the mechanical strength and toughness of DNAN/RDX systems. The above observations revealed that the cooperative effects of the APER polymer can help to reinforce the interfacial interactions and mechanical properties of DNAN/RDX composites, which is of importance in the formulation and mechanical evaluation of advanced energetic composites.