THE ESTER THIOL TECHNOLOGY FOR THE STABILIZATION OF PVC

摘要

Fully organic carboxylate esters that contain one or more thiol groups are very effective as primary thermal stabilizers and plasticizers for poly(vinyl chloride) (PVC). These additives are easily obtained by short synthetic routes, and their odors are not unpleasant when they are pure. This paper updates the status of the ester thiol technology, which was licensed for commercialization in 2005, and outlines the mechanism through which the stabilization occurs. The mechanism includes the displacement of labile halogen, the addition of the ester thiols to alkene double bonds, and the scavenging of radical intermediates that result from the reaction of HCI with conjugated polyene sequences. Detailed evidence is presented for the involvement of these free radicals in the autoacceleration of the thermal dehydrochlorination of PVC.