Flame retardant performance of a carbon source containing DOPO derivative in PET and epoxy

The combination of gas-phase and condensed-phase action will contribute to high quality flame retardant. A novel 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardant (DOPO-DOPC), which contains carbon source was synthesized in favor of conducting the effect of gas-phase as well as promoting the char formation in condensed-phase. The chemical structure of DOPO-DOPC was characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). DOPO-DOPC was used as an additive in poly(ethylene terephthalate) (PET) and epoxy resin (EP). The flame retardancy of PET/DOPO-DOPC and EP/DOPO-DOPC composites were studied by limiting oxygen index (LOI) and UL-94 test. The results showed that the incorporation of DOPO-DOPC into PET or EP could obviously improve their flame retardancy. The LOI values of modified PET or EP, which contained 10 wt % DOPO-DOPC reached 42.8 and 31.7%, respectively. The thermogravimetric analysis (TGA) results revealed that DOPO-DOPC enhanced the formation of char residues. The Laser Raman spectroscopy (LRS) was used to investigate the carbon structure of thermal oxidation residues. Because of the combination of the gas phase flame retardant effect of DOPO moiety and the promoting formation of char residues in condensed phase, the PET and EP composites exhibited significant improvement toward flame retardancy. (C) 2016 Wiley Periodicals, Inc.