PET-PCT共聚酯的制备及其热性能研究

由直接酯化法制备了不同1,4-环己烷二甲醇(CHDM)含量的聚对苯二甲酸乙二醇酯-聚对苯二甲酸-1,4-环己烷二甲醇酯(PET-PCT)共聚酯;利用核磁共振表征了合成产物的实际组成及序列结构;采用差示扫描量热和热失重分析研究了共聚酯的结晶特性和热稳定性。结果表明:合成的共聚酯为无规嵌段聚合物,PCT的实际组成均高于投料比,各链段的序列长度与其含量成正比。随着CHDM含量的增加,共聚酯的玻璃化转变温度升高,退火后的试样在低温处和高温处出现了两个熔点,且熔点和焓值随PCT含量的增加而降低。合成产物热稳定性优良,起始分解温度均大于400℃,最大分解温度大于435℃。用Friedman法对热分解动力学的分析,进一步证明共聚酯的热稳定性优良。

Preparation and thermal property of PET-PCT copolyester

Polyethylene terephthalatepoly (ethylene-co-1,4-cyclohexylenedimethylene terephthalate) (PET-PCT) copolyester containing different amounts of 1,4-cyclohexyldimethanol (CHDM) was prepared via direct esterification.The chemical composi- tion and sequence structure of the resulted product were characterized by nuclear magnetic resonance spectroscopy.The crystal- linity and thermal stability of the copolyester were studied by differential scanning calorimetry and thermogravimetric analysis.The result showed that the obtained copolyester was an atactic block copolymer,and the actual composition of PCT was higher than the feed ratio.The sequence length of each segment was proportional with the content.The glass transition temperature was increased with the content of CHDM.Two melting points appeared at low temperature and high temperature separately after annealing the sample.The melting point and enthalpy were decreased with the increase of PCT content.The product had excellent thermal sta- bility with the initial decomposition temperature above 400℃and maximum decomposition temperature above 435℃.The analysis of thermal decomposition kinetics by Friedman method furtherly proved that the copolyester had excellent thermal stability.