Effects of metal stearates on kinetics of first stage carbonization of PVC were studied on the reaction mechanism of S + gG - g'G’+ rR, that is, one gram of PVC（S） is decomposed to the g’grams of gas(G') and r gram of residue(R).
The reaction rate was obtained by analyzing the thermogravimetric curve measured under a constant heating rate. Pure PVC has the reaction order of 3/2 with respect to residual solid weight, while PVC with a metal stearate has first order reaction. From these results, a new reaction mechanism is suggested to explain the thermal decomposition of PVC with metal stearates.
As the oxygen concentration increases, all samples except for PVC with zinc stearate has lower activation energy and easily decomposes while PVC with zinc-stearate shows higher activation energy in the low oxygen concentration range because the probable formation of zinc oxide suppresses the formation of zinc chloride which accelerates dehydrochlorination.