The degradation and charring of flame retarded epoxy resin during the combustion

To study flame retardant mechanism of epoxy resin (EP) by octaphenyl silsesquioxane and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, an experimental method is set up to investigate the residue of the EPs, which is extinguished during the cone calorimeter testing at different times. The chemical structures of the residues are investigated by the FTIR and XPS. The breakdown of EPs network and formation of new crosslinking structure are supported by the FTIR analysis. The changes of C and O concentrations in the condensed phase during the combustion are investigated by XPS in detail. Moreover, formation of organic carbon is uncovered by the plasmon loss curves based on XPS that could track the carbon crosslinking. These results exhibited a whole degradation and charring process of EP during the combustion: degradation of EP chain, more crosslinking charring, and thermal oxidation of the char. Furthermore, a program of combustion and degradation process of EPs is described in this research.