Zirconium dioxide@phosphazene for enhancing mechanical property, flame retardancy, and thermal property of polythiourethane composites

Introducing high strength inorganic nanoparticles has emerged as an effective strategy to optimize the comprehensive properties of polymers, but good dispersion must be maintained to avoid clustering of inorganic nanoparticles. We report a novel phosphazene-coated ZrO2 nanoparticles (ZrO2@PZS) prepared by a simple ultrasonic method to further enhance thermal, mechanical, optical properties and flame retardancy of polythiourethane (PTU). ZrO2@PZS nanoparticles presented good dispersion in composites, with regular spherical core-shell structures exhibiting significant enhancement effects for overall performance of PTU composites, through strong interfacial interaction. Studies revealed that regular spherical ZrO2@PZS strengthened thermal and tensile properties of PTU, which reached 62.8 degrees C and 79.28 MPa respectively. More importantly, PTU composites showed good flame retardancy through catalytic carbonization, condensed phase shielding and gas phase dilution effect of ZrO2@PZS, where the limiting oxygen index was increased to 25.39% from 20.39%. Moreover, the peak heat release rate, total heat release and smoke production rate could be reduced by 23.5%, 27.7% and 40.0%, respectively. In brief, PTU composites show excellent potential in high strength special fireproof lenses.