THERMAL DEHYDROCHLORINATION AND STABILIZATION OF POLYVINYLCHLORIDE INSOLUTION .8. DIALKYLTIN CARBOXYLATES - SUBSTITUTION-REACTION

The behaviour of dialkyltin dilaurates and of various dialkyltin malea tes in the thermal stabilization of polyvinyl chloride (PVC) in soluti on is studied through kinetic measurements of HCI evolution, formation of dialkyltin dichloride, UV analysis of the polyene sequences, FTIR analysis of the carbonyl groups grafted onto the PVC and of the format ion of double bonds, and the changes in molecular weight by size exclu sion chromatography. The substitution of the carboxylate groups is con firmed in all cases and is much more efficient in the case of the male ates than of the dilaurate. However, the substitution reaction occurs only in the earliest stages of the stabilization. On the other hand, a ttempts to trace intermediate monochlorotin derivatives by polarograph y methods or Mossbauer spectroscopy are not conclusive.