Thermal degradation of fire retardant chloroparaffin - metal compound mixtures. Part II: Bismuth compounds

The mechanisms of reactions which occur on heating mixtures of Bi compounds and a chloroparaffin, which are suitable fire retardant additives for polymers, have been studied. BiCl3, which is evolved at a high initial rate by reaction of Bi compounds with HCl eliminated by the chloroparaffin, has a strong catalytic effect on the dehydrochlorination process of the chloroparaffin itself. BiCl3 evolution occurs in a two-stage process: a fast step characterised by a maximum rate at 300°C followed by a slower step which occurs between 300 and 500°C.