Simultaneous improvements of the fire safety, mechanical properties and water resistance of vinyl ester resin composites by introducing microencapsulated ammonium polyphosphate by polytriazole

Achieving a good balance between mechanical properties and flame retardancy of vinyl ester resin (VER) remains a challenge for traditional inorganic retardants. Herein, a reactive coating shell was constructed on the surface of ammonium polyphosphate (APP) through click chemical reaction. The microencapsulated APP (MAPP) was introduced into and reacted with VER matrix. The coating and the reaction between the filler and the matrix bring a dual effect on comprehensive properties. 10 wt% addition of MAPP not only endow material with better fire safety including a limiting oxygen index of 27.1%, 44% reduction of total heat release, and 38% reduction of total smoke production, but also enhance the flexural and notched Izod impact strength compared with pure VER. The composite exhibits enhanced water resistance, as evidenced by relatively less reduction of flexural strength after immersing in boiling water for 6 h. The dual function enhancement strategy can provide new ideas to prepare composites with balanced flame retardancy, water resistance and mechanical properties.