Melt crystallization and thermal properties of graphene platelets (GNPs) modified recycled polyethylene terephthalate (RPET) composites: The filler network analysis

Solution blending was used in this work to prepare graphene platelets (GNPs) modified recycled polyethylene terephthalate (RPET) composites in an attempt to disclose the presence of a filler network structure in the composites. The incorporation of GNP decreased the activation energy and produced nucleating effect on the crystallization of PET without altering the crystal form. The existence of GNP was found to cause an obvious enhancement in complex viscosity and storage modulus of composites via dynamic rheological testing as well as dynamic mechanical thermal analysis (DMTA). The Agari model presented the most reasonable prediction of the thermal conductivity as a function of GNP loading among the thermal conduction models. A four-parameter model (FPM) of melt solidification kinetics coupled with an in-situ temperature measurement agreed fairly with the variation of thermal conductivity versus GNP content, suggesting the formation of a GNP network structure which was also documented by SEM observations on the microstructures of the composites.