Thermal conductivity and mechanical properties of high density polyethylene composites filled with silicon carbide whiskers modified by cross-linked poly (vinyl alcohol)

A thin layer of poly (vinyl alcohol) (PVA) was coated on the surface of silicon carbide whiskers (SCWs) and crosslinked by glutaraldehyde, and then these modified whiskers (mSCWs) were incorporated into high density polyethylene (HDPE) to prepare HDPE/mSCW composites with a high thermal conductivity. The thermal conductivity, mechanical properties, heat resistance, thermal stability and morphology of HDPE/mSCW and HDPE/SCW composites were characterized and compared. The results reveal that the thermal conductivity of both HDPE/SCW and HDPE/mSCW composites increases with the increase of filler loading, and reaches a maximum of 1.48 and 1.69 W/(m K) at 40 wt% filler loading, which is 251.2% and 300.75% higher than that of HDPE, respectively. Significantly, HDPE/mSCW composites have a higher thermal conductivity than their HDPE/SCW counterparts with the same filler loading. In addition, the heat resistance, Young's modulus and yield strength of both HDPE/SCW and HDPE/mSCW composites are also improved compared with that of HDPE. mSCW can be homogenously dispersed in the HDPE matrix, which contributes to the formation of thermally conductive networks by the inter-connection of mSCWs.