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

The behaviour of dialkyltin dilaurates and of various dialkyltin maleates in the thermal stabilization of polyvinyl chloride (PVC) in solution 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 formation of double bonds, and the changes in molecular weight by size exclusion chromatography. The substitution of the carboxylate groups is confirmed in all cases and is much more efficient in the case of the maleates than of the dilaurate. However, the substitution reaction occurs only in the earliest stages of the stabilization. On the other hand, attempts to trace intermediate monochlorotin derivatives by polarography methods or Mossbauer spectroscopy are not conclusive.