Studies in the utilisation of epoxidised vegetable oils as thermal stabiliser for polyvinyl chloride

Epoxidised Jatropha seed, Khaya seed and rubber seed oils were prepared at 29 degreesC by using peracetic acid generated in situ by reacting glacial acetic acid and hydrogen peroxide. The barium, cadmium and lead soaps of the epoxidised oils are prepared by metathesis in aqueous alcohol solution. The effects of the epoxidised vegetable oils and their metal soap derivatives on the rate of the thermal degradation of polyvinyl chloride and on the viscosity of the polymer samples degraded at 190 degreesC were studied. The effectiveness of the additives (epoxidised oils and their metal soaps) in stabilising polyvinyl chloride against thermal degradation was assessed by comparing the kinetic and viscosity data obtained for the degradation of the polymer in the presence of the additives with corresponding values obtained in the absence of the additives. It was found that the additives retard the rate of degradation and reduce the extent of polymer chain scission associated with the thermal degradation of polyvinyl chloride. The metal soaps of the epoxidised oils were found to be generally more effective than the epoxidised oils in stabilising polyvinyl chloride against thermal degradation. (C) 2002 Elsevier Science B.V. All rights reserved.