Thermal, electrical, and mechanical properties of Si₃N₄ filled LLDPE composite

Abstract Silicon nitride (Si₃N₄) filled linear low‐density polyethylene (LLDPE) composite was prepared. The effects of Si₃N₄ filler content, dispersion, and LLDPE particle size on the thermal conductivity, and Si₃N₄ filled content on the mechanical and electrical properties of Si₃N₄ reinforced LLDPE composites prepared using powder mixing were investigated. The results indicate that there existed a unique dispersion state of Si₃N₄ particles in LLDPE, shell‐kernel structure, in which Si₃N₄ particles surrounded LLDPE matrix particles. With increasing filler content and LLDPE particles size, thermal conductivity increased, and reached 1.42 W/m K at 30 vol% of filler, seven times as that of unfilled LLDPE. Furthermore, the examinations of Agari model demonstrate that larger size LLDPE particles form thermal conductive networks easily compared with smaller ones. The values predicted by theoretical model underestimate the thermal conductivity of Si₃N₄/LLDPE composites. In addition, the composites still possessed rather higher electrical resistivity and dielectric properties, but the mechanical properties decreased. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers