A REVIEW OF THE ROLE OF IRON CONTAINING COMPOUNDS IN CHAR FORMING SMOKE SUPPRESSING REACTIONS DURING THE THERMAL-DECOMPOSITION OF SEMIRIGID POLY(VINYL CHLORIDE) FORMULATIONS

The mechanism of how iron compounds affect char forming reactions during the thermal degradation of semi-rigid poly(vinyl chloride) (PVC) containing dioctylphthalate (DOP) plasticizer is discussed. Work from earlier studies with PVC both in rigid and semi-rigid systems is reviewed and chemical reactions involving iron species acting in char forming/smoke suppressing reactions are suggested. The involvement of reactive intermediates derived from a range of inorganic and organometallic iron compounds in the overall reaction pathway are proposed. The key role of plasticizer degradation and hydrogen chloride formation is highlighted as being important in the formation of smoke during the thermal decomposition of PVC formulations.