Synergistic and compatibilizing effect of octavinyl polyhedral oligomeric silsesquioxane nanoparticles in polypropylene/intumescent flame retardant composite system

This paper reported high-efficiency flame retarded polypropylene (FR PP) composites with combination of a novel single-component intumescent flame retardant (IFR) RMAPP and an octavinyl polyhedral oligomeric silsesquioxane (OV-POSS) as the synergist and compatibilizer. The morphology, crystallization behavior, flame retardancy, flame-retarding mechanism and mechanical performance of the obtained FR PP materials were systematically investigated. The results show that incorporation of POSS can obviously improve the dispersion and compatibility of RMAPP in FR PP system through coating of POSS nanoparticles on surface of big RMAPP FR particles. Relative to RMAPP, the obtained POSS/RMAPP composite particles show the enhanced heterogeneous nucleation effect on PP. Incorporation of POSS nanoparticles also significantly enhances flame retardancy and mechanical performance of FR PP materials. The mechanism for POSS synergistic effect in FR PP system is explained by the remarkably reinforced condensed char layers with SiO2 particles from POSS decomposition and PP macromolecular chains participated in char formation.