Synergistic effect of organic-Zn(H2PO2)2 and lithium containing polyhedral oligomeric phenyl silse-squioxane on flame-retardant, thermal and mechanical properties of poly(ethylene terephthalate)

A novel synergy flame retardant system of poly(ethylene terephthalate) (PET)/organic-Zn(H 2 PO 2 ) 2 /lithium containing polyhedral oligoheptyl silse-squioxane (Li-Ph-POSS) composites was prepared by the melt-blending method to improve the flame retardancy of PET. The synergistic effect of organic-Zn(H 2 PO 2 ) 2 and Li-Ph-POSS on the flame retardancy, thermal, and mechanical properties of the PET composites was investigated by the limiting oxygen index, vertical burning test, cone calorimeter, thermogravimetric analysis, differential scanning calorimeter, tensile tester, and dynamic mechanical analysis, respectively. The results show that the synergistic flame retardant effect between organic-Zn(H 2 PO 2 ) 2 and Li-Ph-POSS improves both the flame retardancy and the crystallization of PET. Moreover, the Li-Ph-POSS has a positive effect on the mechanical property of PET. This work provides a promising strategy for mitigating the fire hazard of PET using this synergy flame retardant system.