Mechanistic Study of the Flame Retardancy of Epoxy Resin With a Novel Phosphorus and Silicon-Containing Flame Retardant

An epoxy resin (EP) composite with a novel phosphorus and silicon-containing flame retardant (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-polyvinylsilicone-polyphenylaminosilicone, DOPO-V-PA) was prepared in this study. From the cone calorimeter measurements, it was confirmed that the EP/DOPO-V-PA (FREP) composite had relatively better flame retardancy than pure EP. The activation energy was calculated with the Kissinger and Ozawa–Flynn–Wall methods. The results showed that the activation energies of pure EP had slightly higher values than the FREP composite in the early and middle degradation stage (conversion ≤ 90% spaces), which indicated that the earlier degradation of the DOPO-V-PA at low temperature accelerated the degradation of the EP matrix. However, the activation energy values of the FREP were higher than those of pure EP in the final stage, which are attributed to the thermal stabilization effect of the DOPO-V-PA through the promoting of EP char formation.