Synthesis of decorated graphene with P, N-containing compounds and its flame retardancy and smoke suppression effects on polylactic acid

Functionalized graphene (PNFR@RGO) has been fabricated by decorating chemically reduced graphene oxide (RGO) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and branched polyethylenimine (BPEI) in this work. PNFR@RGO is then used to reduce the flammability of polylactic acid (PLA) via a melt compounding protocol. X-ray photoelectron spectroscopy (XPS) and Infrared spectroscopy (IR) have confirmed the successful fabrication of the target PNFR@RGO. The chemical decoration introduces phosphorus and nitrogen elements to the GO which can combine the formation of compact char barriers from graphene nanosheets and the elimination of free radicals when ignited or heated. The results show that the degradation temperature in air is increased and the heat release rate (HRR) is reduced. With the addition of 4 wt% PNFR@RGO, the average specific extinction area (ASEA) and the total smoke release (TSR) of PLA are noticeably suppressed by 92% and 79%, respectively. This is attributed to the combination of the corridor barrier functions of RGO and the radical-scavenging effects of PNFR.