Thermal properties, structure and morphology of graphene reinforced polyethylene terephthalate/polypropylene nanocomposites

Abstract

In this work the thermal properties, structure and morphology of a blend of polyethylene terephthalate (PET) and polypropylene (PP) reinforced with graphene nanoplatelets (GNP) were investigated. A blend of PET/PP (70/30 weight percent) compatibilized with styrene-ethylene-butylene-styrene grafted maleic anhydride triblock copolymer (10 phr) were fabricated by melt extrusion process in a twin screw extruder. The effective thermal conductivity of the nanocomposites increased as a function of the GNP concentration. More than 80% increase in effective thermal conductivity was observed for the 7 phr reinforced sample compared to the neat blend. This observation was attributed to the development interconnected GNP sheets which formed heat conductive bridges that are suitable for maximum heat transfer. However, in the case of thermal stability which is a function of dispersibility of GNP in polymer matrix, the maximum increase was observed at 3 phr GNP loading which could be attributed to the uniform dispersion of GNPs in the matrix. It is explained that the GNP nanofillers migrated to the surface of matrix forming an effective oxygen barrier due to char formation. Morphological studies revealed uniform dispersion graphene in the polymer matrix at 3 phr GNP loading along with isolated instances of exfoliation of the graphene layers.