Thermal dehydrochlorination of pure PVC polymer: Part I—thermal degradation kinetics by thermogravimetric analysis,Journal of Applied Polymer Science

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Thermal dehydrochlorination of pure PVC polymer: Part I—thermal degradation kinetics by thermogravimetric analysis
Journal of Applied Polymer Science ( IF 2.7 ) Pub Date : 2021-02-13 , DOI: 10.1002/app.50598
Patrick Pimenta R. Cruz ₁ , Leonardo Cerqueira Silva ₁ , Raildo A. Fiuza‐Jr ₂ , Humberto Polli ₁

Affiliation

Thermal degradation of PVC occurs in two stages, with each stage subdivided into two substages. The first refers to the dehydrochlorination, where hydrochloric acid is formed, and giving polyene structures. Hitherto, the degradation mechanism and action of hydrochloric acid as a catalyst during the dehydrochlorination stage are poorly known. Recently, the importance of the tacticity has gained attention for its influence on the dehydrochlorination mechanism. The present work focused on the dehydrochlorination stage, studying the molecular structure by FTIR analysis and the kinetic parameters by TGA analysis in Nitrogen atmosphere, based on three mathematical methods: Friedman, Kissinger, and Flynn‐Wall‐Ozawa. The sample was a pure homopolymer obtained by suspension polymerization. The dehydrochlorination kinetics follows a first order reaction model and occurs by nucleation and growth. The dehydrochlorination begins with the loss of very labile chlorine atoms present in defective and isotactic molecular segments. The formed HCl acts as a catalyst in the degradation. Following 40% conversion, a drop in Ea is observed. After that, chlorine atoms present in syndiotactic and atactic sequences, are released and, added to the large number of polyene chain sequences, and an increase in Ea is observed up to 60% conversion, where the dehydrochlorination stage is concluded.

中文翻译：

纯PVC聚合物的热脱氯化氢：第I部分-通过热重分析的热降解动力学

PVC的热降解分为两个阶段，每个阶段又分为两个子阶段。第一种是指脱氯化氢作用，即在其中形成盐酸，并得到多烯结构。迄今为止，在脱氯化氢阶段中盐酸作为催化剂的降解机理和作用尚不为人所知。近来，该策略的重要性因其对脱氯化氢机理的影响而受到关注。目前的工作集中在脱氯化氢阶段，基于三种数学方法：Friedman，Kissinger和Flynn-Wall-Ozawa，研究了氮气氛中FTIR分析的分子结构和TGA分析的动力学参数。样品是通过悬浮聚合获得的纯均聚物。脱氯化氢动力学遵循一级反应模型，并通过成核和生长而发生。脱氯化氢反应开始于有缺陷和等规分子链段中存在的非常不稳定的氯原子的损失。形成的HCl在降解过程中起催化剂的作用。转化率达到40％后，观察到Ea下降。之后，间规和无规序列中存在的氯原子被释放，并被添加到大量的多烯链序列中，并且观察到Ea的增加高达60％的转化率，从而结束了脱氯化氢阶段。观察到Ea下降。之后，间规和无规序列中存在的氯原子被释放，并被添加到大量的多烯链序列中，并且观察到Ea的增加高达60％的转化率，从而结束了脱氯化氢阶段。观察到Ea下降。之后，间规和无规序列中存在的氯原子被释放，并被添加到大量的多烯链序列中，并且观察到Ea的增加高达60％的转化率，从而结束了脱氯化氢阶段。

更新日期：2021-03-22

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