EFFECT OF ALIGNMENT ON THERMAL CONDUCTIVITY OF POLYETHYLENE-GRAPHENE COMPOSITES AND COMPARISON WITH EFFECTIVE MEDIUM THEORY

Abstract

Polymers show low thermal conductivity (<0.5 W/mK) in comparison to metals (>20 W/mK). Increased thermal conductivity of polymers can lead to useful applications in industry. The main objective of this research is to analyze the effect of alignment of polymer lamellae and graphene nanoplatelets on thermal conductivity enhancement of polymer-graphene nanocomposites. Role of increase of graphene content in polyethylene-graphene nanoplatelet (PE-GNP) composite materials is also studied. A twin conical screw micro compounder is used to prepare PE-GNP composites with 9 weight% and 13 weight% graphene nanoplatelet. Linear mechanical stretching is used to achieve alignment of polymer and graphene. Thermal conductivity of nanocomposite samples is measured using Angstrom Method. To analyze the alignment of GNP flakes, Laser Scanning Confocal Microscopy (LSCM) is used. Effective medium theory (EMT) is used to compare predicted and measured thermal conductivity values. Thermal conductivity, k values obtained from EMT model indicate an agreement with experimentally measured values for 9 weight% and 13 weight% GNP content in the composite.