THERMAL DEHYDROCHLORINATION AND STABILIZATION OF POLY(VINYLCHLORIDE) IN SOLUTION .11. SYNERGISM BETWEEN DIALKYLTIN THIOGLYCOLATES AND ORGANIC COSTABILIZERS

Secondary organic stabilizers are known to give synergistic effects wi th metal soap stabilizers in the thermal stabilization of poly(vinylch loride) PVC. In this study, it is shown that some of them are also goo d costabilizers with dioctyltin thioglycolate (DOTTG). Epoxidized soya bean oil (ESO), already in practical use, is the best, followed by bet a-diketone derivatives (BDK) and finally dihydropyridine derivatives ( DHP). The order does not change whether the atmosphere is argon or air , although the induction periods of the systems are highly reduced in the latter case. In the melt, under dynamic condition, it appears that the ternary system DOTTG-BDK-ESO shows the best synergistic effect bo th for initial coloration and for long-term stability.