Organic thermal stabilizers for rigid poly(vinyl chloride) VIII. Phenylurea and phenylthiourea derivatives

摘要

Phenylurea and phenylthiourea. derivatives have been investigated as thermal stabilizers or co-stabilizers for rigid PVC in air, at 180 degreesC. The results reveal the higher stabilizing potency of the investigated organic stabilizers as compared with commercial reference stabilizers, which is proved by their greater induction period values, but with higher dehydrochlorination rate at the later stages of degradation. Complexation of these materials with the chlorides of Ni2+ and Cd2+ greatly improved the induction period values, however the dehydrochlorination rate is only slightly improved. On the other hand, blending the investigated thermal stabilizers with some of the commercially known reference stabilizers in different proportions leads to a true synergistic effect. The induction period values and the degradation rate were remarkably improved. A probable mechanism for the stabilizing action of phenylurea and phenylthiourea derivatives has been proposed. (C) 2003 Elsevier Science Ltd. All rights reserved. [References: 20]