Polyamide composites containing graphene nanoplatelets produced via thermomechanical exfoliation

Abstract

Composites are prepared via melt blending polyamide (PA) with flake graphite and graphene nanoplatelets (GNPs); the latter are produced via thermomechanical exfoliation (TME) processing of graphite. The electrical percolation threshold of the GNP composites is around 30 wt%, with a peak conductivity of 10−1 S/m at 40 wt% loading, whereas the graphite composites do not show typical percolation behaviour. In the presence of the GNPs and graphite the thermal conductivity of the composites increases, with the graphite composites exhibiting a conductivity of 2.74 W/mK at 40 wt% loading. Both graphite and GNP containing composites exhibit an increase in flexural modulus of up to 140% with respect to the neat matrix, at 40 wt% filler loading; the impact strength of the PA/GNP composites increased by up to 200% at 20 wt% loading, compared to the neat PA. Ternary composite blends containing PA with a maleated ethylene-octene copolymer (EOC), and 30 wt% GNPs result in further improvements of the toughness of the composite, with a peak impact strength of 150 J/m (650% increase over the neat PA).