Effect of a novel P/N/S-containing reactive flame retardant on curing behavior, thermal and flame-retardant properties of epoxy resin

A novel P/N/S-containing flame retardant DHBAZ was synthesized with 9, 10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, p-hydroxybenzaldehyde and 2-aminothiazole, and used as a co-curing agent for epoxy resin (EP). With the aid of DHBAZ, EP/7.5% DHBAZ passed UL-94 V-0 rating, and owned a LOI value of 31.4%. Besides, DHBAZ also played a positive role in inhibiting the release of heat and the production of smoke. Through non-isothermal DSC tests it revealed that in the presence of DHBAZ, epoxy resin was cured at a lower temperature and showed lower curing-reaction activity energy. DMA analyses indicated that EP/7.5% DHBAZ showed an increased storage modulus, and it had a close glass transition temperature with EP. While, DHBAZ presented a decreased effect on the thermal stability of epoxy resin acquired from TG analyses. Finally, the flame-retardant mechanism studied by TG-FTIR and py-GC/MS deduced that DHBAZ worked in the gaseous phase by producing P center dot, PO center dot and incombustible gases.