ABSTRACT:The mechanism and kinetics of curing of epoxy resin with poly(m-phenylene methylphosphonate) (PMP) was studied by extraction and swelling experiments, DSC, 31 P NMR, and FTIR. It was shown that at linear heating of 20°C/min PMP cures bisphenol A type epoxy resin at 230 -300°C, whereas in the presence of catalytic amount of 2-methyl imidazole the curing occurs at 200 -230°C. Under isothermal conditions, epoxy resin was cured with PMP after 40 -70 min at 150°C. An unusual mechanism of curing due to opening and insertion of epoxy into the phosphonate bond was suggested.
Two new 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-containing compounds, (6,6′-(1-methylethylidene)-bis(9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide)) (bis-DOPO) and 2,4,6-tris-(9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide)-1,3-diacetoxybenzene (DOPO-RA), were synthesized and characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopy. These new flame retardants were incorporated into epoxy formulations to produce a copper-clad laminate. When fully cured, the DOPO-groups of bis-DOPO become a part of the epoxy chains, whereas the DOPO-groups of DOPO-RA remain pendant to the epoxy polymer network. Despite their higher phosphorus content, bis-DOPO-based laminates showed a poorer flame-retardant performance compared to the DOPO-RA laminates. It is believed that the pendant position of the DOPO group with respect to the polymer chains is essential for a gas-phase flame-retardant action.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.