A novel phosphazene cyclomatrix network polymer: Design, synthesis and application in flame retardant polylactide

A novel phosphazene cyclomatrix network polymer poly(cyclotriphosphazene-co- pentaerythritol) (PCPP) was synthesized and characterized based on an attempt to look for a high efficient and green intumescent flame retardant. A series of flame retardant polylactide (FR-PLA) composites containing PCPP were prepared by melt blending method. Thermal degradation behavior and combustion properties of FR-PLA composites were evaluated through thermogravimetric analysis, UL-94 experiments, limiting oxygen index and cone calorimeter tests. It is found that the weight of residues for FR-PLA composites improved greatly with the addition of PCPP. Additionally, PCPP show a high flame retardant efficiency for PLA, UL-94 V-0 could be passed only containing 5 wt% PCPP. Fourier transform infrared spectra and scanning electronic microscopy investigations reveal that the residual chars are compact and foaming containing P-O-C structure, which restrains the development of fire and increases the flame retardant properties.