摘要
监测了对－乙酰氧基苯甲酸与聚对苯二甲酸乙二醇酯（ＰＥＴ）共缩聚反应过程中１ＨＮＭＲ图谱及特性粘度的变化，对乙酰氧基酯交换反应及乙酰脂肪酯的反应活性进行了研究。并研究了以低分子量ＰＥＴ或对苯二甲酸二乙二醇酯为原料时反应中醚键的形成及其进入共聚酯链的规律性。
The transesterification reaction of acetates and etherification reaction during the polycondensation reaction of p-acetoxybenzoic acid (Ac-PHB)and poly(ethylene terephthalate)were studied by analyzing the reaction mixture sampled after different reaction time by ￣1H NMR spectra and [η] determination.Just in the beginning of the polycondensation reaction the PET chains degraded vigorously with the formation of acetoxy ethylene end groups of about 25% (molar ratio)of total ethylene content. Both the acetoxy ethylene and acetoxy phenylene end groups were reactive toward the polycondensation reaction.Using PET of low molecular weight or bis-hydroxyethylene terephthalate as the original material, the copolyester of high molecular weight could be prepared.However, it's T_f and HDT were lower, and the solubility was higher than those as PET of high molecular weight was used. These poor properties of copolyester were explained by the high content of ethylene groups and the formation of ether bonds, among which the semi-aromatic ether content is much higher than the aliphatic one. Both the two ether bonds could react with carboxy end groups to propagate the chains under vacuum reaction condition .
出处
《高等学校化学学报》
CSCD
北大核心
1996年第5期824-828,共5页
Chemical Journal of Chinese Universities
基金
国家自然科学基金
关键词
液晶
共聚酯
羟基苯甲酸
PET
酯交换反应
Liquid crystalline copolyester
Poly(4-oxybenzoate-co-ethylene terephthalate)
Acetate transesterification reaction
