Effects of temperature and wax binder on thermal conductivity of RDX: A molecular dynamics study

In this work, based on the ReaxFF-lg reactive force field, the effects of temperature and wax binder on RDX thermal conductivity were studied by using molecular dynamics simulation (MD). The non-equilibrium molecular dynamics (NEMD) method was used to calculate the heat transfer process of RDX crystals with different sizes and at different temperatures and for RDX/wax mixtures with different ratios. The contribution of acoustic and optical phonons to the thermal conductivity was calculated using a thermal conductivity decomposition procedure. The heat transfer process of the RDX supercell and the RDX/wax mixtures were analyzed via calculation of the vibrational density of states. The thermal conductivity of the RDX increased with increasing temperature while the temperature was below 298 K, and decreased slightly with increasing temperature while the temperature was above 323 K. The interfacial thermal resistance between RDX and wax was the main factor that led to a decrease in the thermal conductivity of the RDX/wax mixed explosives. Acoustic phonons played a major role for heat transfer in RDX and mixed RDX explosives. An increased temperature resulted in more frequent expansion or torsion of the bonds in the optical modes, resulting in a slight reduction in the thermal conductivity.