Mechanisms of action of phosphorus based flame retardants in acrylic polymers

The fire-induced degradation chemistry of a random copolymer of methyl meth acrylate with a flame retardant phosphate-methacrylate comonomer has been s tudied to gain an insight into the mechanisms of fire retardancy in the mod el system and thus help to provide a fundamental basis for the further deve lopment of fire resistant poly(methyl methacrylate)s. To obtain information about the fire-induced condensed phase degradation ch emistry of the model system, surface analytical techniques have been exploi ted to assemble a picture of the chemical nature of the surface char presen t on fire-tested samples. A number of analytical techniques were utilized i n these studies, including X-ray photoelectron spectroscopy (XPS), time-of- flight secondary ionization mass spectroscopy (TOF-SIMS), nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (IR) spectrosco py. In addition, the model flame retardant copolymer was subjected to combi ned thermogravimetric and evolved gas analysis (TGA-EVA) to identify the ch emical nature of the volatile species evolved upon thermal degradation. Using the analytical data accumulated, a mechanism is proposed for the cond ensed phase mode of action of the phosphate-based flame retardant in the mo del methacrylate copolymer. (C) 2000 Society of Chemical Industry.