Enhancement of fire retardancy performance of glass-fibre reinforced poly(ethylene terephthalate) composites with the incorporation of aluminum hypophosphite and melamine cyanurate

This work aims to develop glass-fibre reinforced poly(ethylene terephthalate) (PET/GF) composites with significantly improved flame retardancy using aluminum hypophosphite (AHP) and melamine cyanurate (MC). Microscale combustion calorimetry (MCC) and thermal gravimetric analysis/infrared spectrometry (TG-IR) technique were used to investigate the potential fire hazards of various PET/GF composites. For the PET/GF composites with a low loading of the flame retardant mixture, the heat release capacity (HRC) which is an indicator of a material fire hazard reduced by 47%, meanwhile, the intensities of a variety of combustible or toxic gases detected by TG-IR technique were remarkably decreased. A loading of 10 wt.% AHP alone or its combination with MC could give the PET/GF composites high limited oxygen index and V-0 classification in UL-94 test. Thermal decomposition and residue analysis revealed that the flame retardancy of PET/GF composites is enhanced by the condensed-phase action of AHP and the gas-phase dilution effect of MC.