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研究了芳香族二醇单体与聚对苯二甲酸丁二酯(PBT)的固态缩聚反应及其反应动力学.采用的二醇单体是对苯二甲酸二羟乙酯(BHET).一定配比的PBT和BHET混合物在185°C下进行固态缩聚(SSP)反应,分别利用凝胶色谱(SEC)、核磁共振氢谱(1H-NMR)和核磁共振碳谱(13C-NMR)对缩聚产物的数均分子量、分子结构进行了表征.SEC表征的结果表明:反应起始阶段聚合物的数均分子量快速下降,这是由于酯交换导致PBT链的断裂,形成了低聚物;0.5 h后,所有自由的BHET单体都已参与了酯交换反应;此后,所得到的低聚物重新缩聚,导致数均分子量上升,最终得到高数均分子量共聚物.1H-NMR表征结果表明,随着固相反应的进行乙二醇基团在体系中趋于无规分布.13C-NMR表征结果表明:在反应起始阶段,体系自由度快速上升;反应4 h后,自由度开始趋于缓和,所得共聚物的化学结构趋于稳定.
The solid state polycondensation reaction of aromatic diol monomer with polybutylene terephthalate (PBT) and its reaction kinetics were studied.The diol monomer used was BHET The mixture of PBT and BHET was subjected to solid state polycondensation (SSP) at 185 ° C. The polycondensation of polycondensation of PBT and BHET was carried out by gel permeation chromatography (SEC), 1H-NMR and 13C-NMR, respectively The number average molecular weight and the molecular structure of the product were characterized.The results of SEC characterization showed that the number average molecular weight of the polymer decreased rapidly at the initial stage of the reaction due to the transesterification of the PBT chain and the formation of oligomers. After all the free BHET monomer has been involved in the transesterification reaction; thereafter, the resulting oligomer re-polycondensation, resulting in a rise in the number average molecular weight, the final high number average molecular weight copolymer.1H-NMR characterization results show that with The solid-phase reaction of ethylene glycol groups tended to be randomly distributed in the system.The results of13C-NMR characterization showed that the degree of freedom of the system increased rapidly at the initial stage of reaction, and the degree of freedom began to relax after 4 hours , The chemical structure of the resulting copolymer tends to be stable.