聚对苯二甲酸甲二酯的热分解行为及其动力学研究

研究了惰性气氛下聚对苯二甲酸甲二酯(PMT)的非等温热分解行为及其动力学,并与聚对苯二甲酸丁二酯 (PBT)进行了对比。研究发现,PMT的热降解过程包括两个主要失重阶段,其热分解反应不是一级反应。第一阶段的起始分解温度较低是由于产物的分子链末端基中含有Br或Cl能催化聚合物的降解反应;第二阶段为分子链主体的热分解过程,由于分子链中苯环的密度较大,分子链的热稳定性比具有较低苯环密度的PBT要高。而PBT的降解失重过程仅为一个阶段,为一级反应。

Thermal Degradation and Its Kinetics of Poly(methylene terephthalate)

The non-isothermal degradation behavior of poly(methylene terephthalate)(PMT) and poly (butylene terephthalate) (PBT) were studied by using thermogravimetry (TG) analysis in nitrogen. The non-isothermal degradation of PMT was not a first order reaction and two degradation stages were identified. At the lower temperature stage, the decomposition was catalyzed by the Cl- or Br- at the molecule ends. The high temperature stage involved the decomposition of benzene rings. The apparent activation energies (E) of both degradation stage of PMT were calculated using Ozawa method. In contrast, PBT gave only one stage of degradation as a first order reaction.