Thermal response of encapsulated nanoscale phase change materials with crosslink: A molecular dynamics study

Abstract

Crosslink plays a key role in improving the thermal and mechanical stability of encapsulated phase change materials (EPCM). In this paper, molecular models of EPCM with different crosslinked density (non-crosslinked, 20 %, 40 %, 60 %, and 80 %) were constructed and then the molecular dynamics method was employed to investigate the thermal response characteristics. Specifically, the local structural characteristics, overall morphology, kinetic properties, and thermo-mechanical properties were analyzed. The results indicate that establishing crosslinked structures effectively enhances the structural steadiness of the EPCM under thermal and mechanical effects, and restricts the radial thermal diffusion of the core substance. More precisely, the presence of crosslinked structure (80 % crosslinked density) led to a 26.61 % improvement in tensile strength, a 5.59 % increase in compression resistance, and a 14.4 % improvement in shear strength than non-crosslinked structure. It is worth mentioning that, the results indicate a remarkable turning point in the occupancy volume change and mechanical properties of the system around the crosslinked density of 40 %.