THERMAL-ANALYSIS OF PLASTICIZED PVC CONTAINING FLAME-RETARDANT SMOKE SUPPRESSANT INORGANIC AND ORGANOMETALLIC IRON COMPOUNDS

Iron additives, both inorganic and organometallic, destabilise poly(vinyl chloride) (PVC) formulations as earlier workers have shown for both rigid PVC and, to a more limited extent, plasticised PVC. This destabilisation is correlated with smoke suppressant activity and, with the exception of ferrocene, correlated to flame retardant activity. Ferrocene is unusual in functioning primarily as a gas phase flame retardant, although its smoke suppressant activity is probably a condensed phase process. The other additives function as both flame retardants and smoke suppressants by a condensed phase mechanism, i.e. by char promotion. The correlations between thermogravimetric and differential scanning calorimetric results with limiting oxygen index flammability and National Bureau of Standards smoke data suggest that thermal analysis, requiring only small amounts of sample, could be used to help screen compounds for smoke suppression and flame retardancy.