Thermal degradation of polymer - fire retardant mixtures. Part VII: Products of degradation and mechanism of fire retardance in polystirene - chloroparaffin mixtures

The composition of the products formed by the thermal degradation of PS is modified by the presence of a fire retardant chloroparaffin. In particular, chain fragments with more than one phenyl group are evolved in larger yield from polystyrene in the mixtures than from the pure polymer, whereas the yield of monomer is decreased. A mechanism of degradation of polystyrene in the mixtures is proposed which accounts for the volatile products evolved. The mechanism of fire retardance by the chloroparaffin is discussed and shown to derive from its action on the thermal degradation reactions which occur in the condensed phase in burning polystyrene.