A ternary polymer flame retardant and its synergistic flame retardant effect with piperazine pyrophosphate in EP

Combining bio-based functional reagents and biopolymers has become a solution to address the needs of sustainability, health, and safety as society has grown. This study developed a waterproof and intumescent flame retardant system for epoxy resin (EP) by combining hexachlorocyclotriphosphazene and melamine with vanillin, synthesizing a ternary polymer flame retardant (HCPVM), combining carbon and gas sources, and using piperazine pyrophosphate (PAPP) as an acid source. The test results showed that HCPVM could participate in the curing reaction of EP and improve the mechanical properties of EP material. At the same time, the flame retardancy and water resistance of the material have been significantly improved. The peak heat release rate (PHRR) of EP/3.5 PAPP/0.5 HCPVM was 65.43% lower than that of pure EP. Additionally, the system's LOI and UL-94 did not significantly change after five days of boiling. In summary, this study's waterproof bio-based intumescent flame retardant solution broadens the application possibilities for EP. Graphical abstract