Abstract: An extrusion die with two shunt plates was designed to provide high shear effect. The effect of shear on morphology, thermal conductivity, electrical conductivity, and crystallization behavior of polypropylene/graphene nanoplatelet nanocomposite was investigated. It showed that the shear rate of the extrusion die with two shunt plates was eight times that of the extrusion die without two shunt plates. This improved the exfoliation and orientation of graphene nanoplatelets and crystallinity of the nanocomposites, and reduced the electrical percolation threshold from 10 % to 8 %. When the graphene nanoplatelets content reached 12 %, the thermal conductivity of nanocomposites extruded by the die with and without two shunt plates were 1.20 W/(m·K) and 0.90 W/(m·K), respectively.

Key words: graphene nanoplatelets, shear rate, orientation, thermal conductivity, electrical conductivity