Organic thermal stabilizers for rigid poly(vinyl chloride).Part X: N-acryloyl- N′- p-substituted phenylthiourea derivatives

Abstract

N-Acryloyl- N′- p-substituted phenylthiourea derivatives have been examined as thermal stabilizers or co-stabilizers for rigid poly(vinyl chloride) in air, at 180 °C. Their high stabilizing efficiency is proved by their higher induction period if compared with dibasic lead carbonate, barium–cadmium–zinc stearate and dibutyl tin maleate reference stabilizers used industrially, but with higher dehydrochlorination rate and higher extent of discoloration. Mixing these derivatives with reference stabilizers in different proportions greatly improves both the induction period and the degradation rate. A probable ionic mechanism for the stabilizing action of N-Acryloyl- N′- p-substituted phenylthiourea derivatives has been proposed. The stabilizing efficiency is attributed to the replacement of the labile chloride ions on the PVC chains by a relatively more stable moiety of the organic stabilizer.