Thermal degradation of polymer - fire retardant mixtures. Part V: Polyethylene - chloroparaffin mixtures

Volatilisation of mixtures of high density polyethylene (PE) with a fire retardant chloroparaffin (CP) occurs in two separate steps on programmed heating. CP eliminates HCl at 250-370°C whilst, at 400-530°C, hydrocarbons are formed by quantitative volatilisation of PE. However, chlorine radicals which propagate the thermal dehydro-chlorination of CP induce crosslinking of PE. Furthermore, in the presence of CP, a larger ratio of saturated to unsaturated hydrocarbons is obtained than from PE alone. The fire retardant activity of CP in PE-CP mixtures, although slight, is likely to be of the 'condensed phase' type. This is in agreement with the separate evolution of the flame inhibitor HCl, and flammable hydrocarbons and with the change in the composition of the hydrocarbons evolved by PE degrading in the presence of CP.