Influence of tacticity on the thermal degradation of PVC. VI. New advances in the degradation process through the behavior of modified PVC samples

摘要: Three PVC samples having different tacticities, as well the products resulting from their reaction with sodium thiophenate, which was previously found to occur selectively by some definite isotactic conformations, were degraded at 180°C in solid state up 0.3%. In agreement prior works, stability of substituted polymers shown be higher substitution extent increased a value, depends on overall content starting materials. On other hand, changes polyene distribution for extent, followed UV-visible spectroscopy, demonstrate that specific bands 393, 416, and 437 nm, are known characteristic most unstable PVCs, arise lability chlorine atoms located GTTG′ (or TTTG) results suggested. basis so-obtained correlation between triads (especially GTTG′) both thermal instability formation above-indicated polyenes, new advances degradation mechanism proposed.