Flame retardancy effect of phosphorus graphite nanoplatelets on ethylene-vinyl acetate copolymer: Physical blending versus chemical modification

A novel modified exfoliated graphite nanoplatelets (GNP-g-APP), resulting from grafting ammonium polyphosphate (APP) on exfoliated graphite nanoplatelets (GNP) was prepared and evaluated as flame retardant for ethylene-vinyl acetate copolymer (EVA). The effect of modification on the thermal stability and flame retardancy of EVA was discussed. Thermogravimetric analysis (TGA), UL-94, pyrolysis combustion flow calorimeter (PCFC), and mass loss calorimeter (MLC) analyses were employed for the evaluation of the thermal stability and flame retardancy of composites. The introduction of 20 wt.% GNP-g-APP into EVA resulted in significant enhancement in flame retardant properties with respect to the system containing physical mixture of GNP and APP. The former blend exhibited 57% decrease in the peak of heat release rate (pHRR), and 35% reduction in the total heat release (THR) than the latter one in MLC test. Thus, pHRR was decreased from 940 kW.m(-2) for neat EVA to 403 kW.m(-2) for EVA containing GNP-g-APP. V0 rating (auto-extinguishable behavior) was also observed in UL 94 chemically modified sample. According to the present study, chemical modification of GNP with APP is more effective than a physical mixing of GNP and APP in improving the flame retardant properties of EVA.

Automated summary

The modification of graphite nanoplatelets with ammonium polyphosphate effectively enhances the flame retardant properties of ethylene-vinyl acetate copolymer (EVA) compared to using a physical mixture of the two components. The modified sample showed significant improvements in flame retardancy, with a 57% decrease in peak heat release rate (pHRR) and a 35% reduction in total heat release (THR) compared to the physical mixture.