Wood plastic composites with improved electrical and thermal conductivity

Abstract

Graphene nanoplatelets (GNP) are used to produce wood plastic composites (WPC) with improved electrical and thermal conductivity. The polypropylene/wood/GNP hybrid composites are produced by melt compounding followed by hot pressing. The effect of GNP loadings (5, 10 and 15 wt%) on electrical conductivity, thermal conductivity, tensile properties, and thermal degradation of hybrid WPC containing 20 wt% of wood flour is studied. The effect of fast and slow cooling rates during hot pressing on the surface resistivity of hybrid WPC is evaluated. Scanning electron microscopy of the tensile fracture surface and polished cross-sections of hybrid WPC is analysed. The hybrid WPC containing 20 wt% wood flour and 15 wt% of GNP (PP-W20-G15) is measured to show surface resistivity of 2.05E + 06 Ω/sq and thermal conductivity of 0.61 W/m.K. There is a significant increase in electrical and thermal conductivity of PP-W20-G15 when compared to WPC containing 20 wt% of wood flour (PP-W20). The wood flour helps with the distribution of GNP in PP-W20-G15 by which the surface resistivity is improved when compared to PP filled with 15 wt% GNP. It was found that the surface resistivity of PP-W20-G15 was dependent on the cooling rate used during the hot pressing. There is a considerable decrease in tensile strength and an increase in the tensile modulus of hybrid WPCs compared to PP-W20 and neat polypropylene.