How Phosphorous Flame Retardant Additives Affect Benzoxazine‐Based Monomer and Polymer Properties

The phosphorous-based flame retardant additives poly(m-phenylene methylphosphonate) (PMP) and resorcinol bis(diphenyl phosphate) (RDP) arereacted with bisphenol F and aniline-based benzoxazine (BF-a). DSC, rheological analysis, FT-IR, and soxhlet extraction reveal the covalent incorporation of both FR additives - initiating phenols in PMP structure as well as free phenols generated via transesterification reaction in the case of RDP. In contrast to PMP, RDP elongates the processing window but decreases the thermo-mechanical properties. Both additives increase the resistance in reactions against small flames with solely a phosphorous loadingof 0.3 wt%, resulting in a V-0 rating and an improvement in the OI value by upto 2% for RDP and 4% for PMP. Both FRs reduce the heat release rate but increase the smoke production and the smoke toxicity in the case of RDP.