Enhanced fire retardancy of polyethylene/alumina trihydrate composites by graphene nanoplatelets

In this work, well exfoliated graphene nanoplatelets (GNPs) were prepared and applied to enhance the fire retardancy of polyethylene/alumina trihydrate (PE/ATH) composites. GNPs with thickness about 5 nm were obtained from expanded graphite by ball milling and ultrasonic treatment. A homogeneous mixture of GNPs and ATH was prepared and used to prepare PE/ATH/GNP composites by melt-blending. The fire retardancy of PE/ATH was improved with addition of GNPs. The peak heat release rate of the PE/ATH/GNP composite with only 0.2 wt% GNPs decreased by 18% of that of the PE/ATH composite. The fire retardancy of PE/ATH/GNP composites was influenced by the GNP contents. A char layer of GNPs was revealed on the surface of the residues after combustion testing, which contributed to the enhanced fire retardancy by acting as a heat shield and a barrier against mass transport. The well exfoliated structure of GNPs and its good dispersion with ATH played an important role in the char formation at very low loading of GNPs. (C) 2014 Elsevier B.V. All rights reserved.