DMC法聚氧化丙烯二醇的降解特性研究  

Study on Degradation Characteristics of DMC-process Polyoxypropylene Glycol

作　　者：张雪婷 胡激江[1,2] 卜志扬 李伯耿[1,2] ZHANG Xueting;HU Jijiang;BU Zhiyang;LI Bogeng(College of Chemical and Biological Engineering of Zhejiang University,State Key Laboratory of Chemical Engineering,Hangzhou 310027,China;Quzhou Institute of Zhejiang University,Quzhou 324000,China)

机构地区：[1]浙江大学化学工程与生物工程学院化学工程联合国家重点实验室,浙江杭州310027 [2]浙江大学衢州研究院,浙江衢州324000

出　　处：《聚氨酯工业》2023年第4期14-19,共6页Polyurethane Industry

基　　金：化学工程联合国家重点实验室自主探索性重点项目(SKL-ChE-18Z02)。

摘　　要：对使用双金属氰化络合物(DMC)催化聚合制得的聚氧化丙烯二醇(PPG)进行了降解规律研究。研究发现:不同分子量的PPG样品在室温空气环境下放置一段时间后,重均和数均分子量均会变小,分子量分布则变窄;且样品分子量越大,这一降解趋势越明显。即使样品已在自然环境中存放了3个月,在较高温度下仍会出现降解,且温度越高,降解速率越快;空气氛围和氮气氛围中降解反应均为一级反应,氮气氛围中的反应速率常数约为空气氛围中的1/3;纯氧气氛中的PPG的降解较空气氛围中的降解更快,为三级反应;可见氧化反应是PPG降解的主因,同时也存在着非氧化的热降解。机理分析表明,稳定自由基类的抗氧化剂虽可抑制PPG的氧化降解,但仍不能消除它的热降解。拟合80~140℃下空气氛围中的降解速率常数计算得到降解活化能为18.9 kJ/mol。样品中残留的催化剂浓度较高时,PPG的降解速率相对较低,可能是由于更多的PPG分子与催化剂配位形成的位阻,减弱了氧气对PPG主链的进攻。The degradation characteristics of polyoxypropylene glycol(PPG)prepared by catalytic polymerizationthe of double metal complex(DMC)were studied.It was found that both weight-average and number-average molecular weights of PPG samples with different molecular weights decreased and their molecular weight distributions narrowed after placing for a period of time at room temperature and air environment.The larger the molecular weight of the sample,the more obvious the degradation trend was.Even if the sample was stored in the natural environment for three months,the degradation still occurred at relative high temperatures.The higher the temperature,the faster the degradation rate was.The degradation reactions in air and in nitrogen atmospheres were first-order reactions,however,the reaction rate constant in nitrogen atmosphere was about one-third of that in air atmosphere.The degradation of PPG in pure oxygen atmosphere was faster than that in air atmosphere,which was a third order reaction.The results showed that the oxidation reaction was the main cause of PPG degradation,and there was also non-oxidative thermal degradation.Analysis of degradation mechanism indicated that the antioxidants which stabilized free radicals could inhibit the oxidative degradation of PPG,but could not eliminate its thermal degradation.The activation energy obtained by fitting the degradation rate constant in an air atmosphere at 80~140℃was 18.9 kJ/mol.When the concentration of residual DMC in the sample was higher,the degradation rate of PPG was relatively low,which could be due to the steric hindrance formed by the coordination of PPG molecules with the catalyst,weakening the attack of oxygen on the main chain of PPG.

关 键 词：聚氧化丙烯二醇 稳定性 降解 机理 动力学 

分 类 号：TQ323.8[化学工程—合成树脂塑料工业]