Time-resolved rheometry of poly(ethylene terephthalate) during thermal and thermo-oxidative degradation
Time-resolved rheometry of poly(ethylene terephthalate) during thermal and thermo-oxidative degradation
复制标题
DOI：
10.1007/s00397-016-0955-2
复制
发表时间：
2016-10-01
期刊：
影响因子：
2.3
通讯作者：
Wagner, Manfred H.
中科院分区：
文献类型：
--
作者：
Kruse, Matthias;Wagner, Manfred H.
采用时间分辨流变仪研究了聚对苯二甲酸乙二酯（PET）的热降解和热氧降解。降解导致空气气氛中的复数粘度垂直下移。我们得出结论，模量和粘度的降低是由低聚物出现断链和增塑剂。此外，在长时间内观察到导致屈服应力的交联。在氮气气氛中，缩聚增加了摩尔质量和粘度，并延长了剪切稀化制度。随着降解时间的延长，热降解占主导地位，并导致垂直向下移动。三种不同摩尔质量的PET的反应动力学通过时间常数τ假设一级动力学进行分析。低分子量PET在空气气氛中表现出最大的时间常数，因此降解速率最低，而高分子量PET表现出小的τ和快速降解。氮素中的增强率则相反。
Time-resolved rheometry was employed to study thermal and thermo-oxidative degradation of poly(ethylene terephthalate) (PET). Degradation results in a vertical downward shift of the complex viscosity in air atmosphere. We conclude that reduction of moduli and viscosity is governed by oligomers emerging from chain scission and acting as plasticizer. Additionally, cross-linking leading to a yield stress is observed at long times. In nitrogen atmosphere, polycondensation increases the molar mass and viscosity and extends the shear thinning regime. With longer degradation times, thermal degradation prevails and leads to a vertical downward shift. The reaction kinetics of three PETs with different molar mass was analyzed by a time constant tau assuming first-order kinetics. The low molecular weight PET exhibits the largest time constant in air atmosphere, and hence the lowest degradation rate, while high molecular weight PET exhibits a small tau and rapid degradation. The enhancement rate in nitrogen is vice versa.