THE EVALUATION OF AN INNOVATIVE COSTABILIZER FOR POLY(VINYL CHLORIDE).1. INHIBITION OF DISCOLORATION AND STABILIZATION PERFORMANCE IN THE POLYMER

The stabilisation performance of a recently patented triketone costabi lser for poly(vinyl chloride) (PVC) in the presence and absence of zin c and calcium stearates has been evaluated. By way of comparison two o ther costabilisers, dibenozyl methane and dehydroacetic acid, have als o been investigated. Although all three costabilisers reduce the induc tion time to degradation of PVC (in comparison to when the metal stear ates are used alone), they also reduce discolouration of the polymer d uring degradation. In particular, the triketone exhibits outstanding i nhibition of discolouration. Observations from both infra-red and lumi nescence spectroscopy suggest the costabilisers coordinate with the me tal soaps. The extent of coordination apparently controls the point in the degradation mechanism when the costabilisers are able to interact with those labile structures which otherwise lead to colour formation . (C) 1996 Published by Elsevier Science Limited.