Flame retardancy and thermal degradation behaviors of phosphate in combination with POSS in polylactide composites

Flame retarded polylactide with pentaerythritol phosphate (PEPA), melamine phosphate (MP) and polyhedral oligomeric silsesquioxanes (POSS) were prepared in this study. Effect of trisilanolisbutyl-POSS (TPOSS) on the thermal degradation behaviors of intumescent flame retardant polylactide (IFRPLA) composites under nitrogen or air atmosphere was investigated by thermalgravimetric analysis (TGA), thermogravimetric analysis/infrared spectrometry (TG–IR) and real time Fourier transform infrared spectra (RTFTIR). Under nitrogen atmosphere, incorporation of PEPA, MP and TPOSS could significantly reduce the release of flammable gases. Under air atmosphere, the presence of MP and PEPA can promote the formation of char layer, while TPOSS was oxidized to form silica covered on the char layer, which improved the thermo-oxidation resistance of the char. Thus, the fire retardancy of PLA was notably improved.

► Flame retarded polylactide composites with phosphate and POSS were prepared.
► Phosphate and POSS exhibited a synergistic effect on flame retardancy of polylactide.
► Incorporation of MP and PEPA significantly reduced the release of flammable gases.