MECHANISM OF ACTION OF ESTER THIOLS AS STABILIZERS FOR PVC

摘要

Organic thiols containing at least one carboxylate ester group (ester thiols) are excellent heat stabilizers for both rigid and plasticized PVC. Their mechanism of action is now shown to involve the deactivation of unstable structural defects by nucleophilic chloride displacement, the retardation and removal of coloration through thiol additions to polyene double bonds, and the prevention of autoacceleration during thermal dehydro-chlorination through polyene shortening reactions and the scavenging of free radicals formed from polyenes and HC1.