Strengthen flame retardancy of epoxy thermoset by montmorillonite particles adhering phosphorus‐containing fragments

Abstract

ABSTRACTPhosphaphenanthrene derivative tri‐(3‐DOPO‐2‐hydroxypropan‐1‐yl)‐1,3,5‐triazine‐2,4,6‐trione (TGD) and organo‐modified montmorillonite (OMMT) were jointly introduced into the diglycidyl ether of bisphenol A cured by 4,4‐diamino‐diphenylmethane (EP) to investigate their flame retardant behaviors. With only addition of 0.5%OMMT and 2.5%TGD, epoxy thermoset achieved a limiting oxygen index value of 33.7% and passed UL 94 V‐0 rating test. Compared with the combustion behaviors of 3%OMMT/EP and 3%TGD/EP, an obvious synergistic flame retardant effect between OMMT and TGD can be concluded in OMMT/TGD/EP. Meanwhile, the FTIR spectra of gas‐phase and condensed‐phase products further proved this synergistic effect working in a physical way. On one hand, the co‐existence of hydroxyl‐containing TGD enabled montmorillonite (MMT) particles to filtrate and adhere more smoke fragments. On the other hand, the co‐action of MMT help the polar phosphorus‐containing fragments from TGD better strengthened char layer, enhancing the barrier and protective effect of residue. The synergistic flame retardant effect from OMMT/TGD system endowed themselves with higher flame retardant efficiency, and epoxy thermoset with better flame retardant performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 47500.