Ignition temperatures and pyrolysis of a flame-retardant methyl methacrylate copolymer containing diethyl(methacryloyloxymethyl)-phosphonate units

The ignition and pyrolysis of some copolymers of methyl methacrylate (MMA) with diethyl(methacryloyloxymethyl)phosphonate (DEMMP) have been studied by a simple tube furnace and by isothermal and non-isothermal TGA. The results indicate that copolymers containing DEMMP thermally degrade, under both air and nitrogen, by a mechanism which is more complex than that (simple depolymerization) for poly(methyl methacrylate) (PMMA). The copolymers containing 10 mol% or more of DEMMP are inherently flame retardant in that they fail to autoignite at 480 °C and take longer to autoignite at 490 °C than PMMA or MMA–DEMMP copolymers containing only 5 mol% DEMMP. The formation of a carbonaceous residue or char on combustion of the MMA–DEMMP copolymers suggests that flame retardance is due mainly to reactions in the condensed phase.