Incorporation of polyethylene fillers in all-polymer high-thermal-conductivity composites

Abstract

This work presents a lightweight electrically insulating composite material for high thermal conductivity: all polymer composites created by mixing ultra-high molecular weight polyethylene flakes into a matrix of low-density polyethylene or ethylene vinyl acetate. The ultra-high molecular weight polyethylene flakes have a reported thermal conductivity of 40 W m−1 K−1, and when 30 volume percent is compounded in an ethylene vinyl acetate matrix, the thermal conductivity is measured to be 2.5 W m−1 K−1 at 52 °C and the notched impact strength is 350 J/m. The temperature stability of the polyethylene flakes is investigated using polarized Raman spectrometry and thermal conductivity measurements, and it is discovered that flakes compounded at temperatures of 115 °C and above show a dramatic drop in thermal conductivity due to melting and reduced polymer chain alignment. This study highlights the possibility of using high-thermal-conductivity polymer fillers in bulk composites for near-room-temperature applications.