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.