摘要
以聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丙二醇酯(PTT)、聚对苯二甲酸丁二醇酯(PBT)为研究对象,采用差示扫描量热仪考察了其亚甲基含量对聚酯的玻璃化转变、熔融结晶行为、冷结晶行为等热性能的影响,通过Avrami方程、Arrhenius方程计算了3种聚酯的结晶物理常数;采用热失重分析仪分析了PET,PTT,PBT的热稳定性。结果表明:PET的玻璃化转变温度为77.24℃,而PTT,PBT未见明显的玻璃化转变;随着亚甲基含量增加,聚酯的熔点下降,冷结晶峰温度上升,其中PTT在67.8,192.0℃处存在两个冷结晶峰;3种聚酯的熔融结晶行为均符合Avrami方程;随着亚甲基含量增加,聚酯的熔融结晶热焓、Avrami指数依次增大,半结晶时间依次减小,校正后的非等温结晶动力学常数变化不大;3种聚酯的冷结晶程度均弱于熔融结晶,PET,PTT,PBT的冷结晶程度分别约为熔融结晶的70%,10%,7%,冷结晶速度依次变快;随着聚酯中的亚甲基含量增加,聚酯的热稳定性变差;3种聚酯的热降解过程可分为3个阶段,PTT,PBT初始分解温度低于PET,第一、第二降解活化能高于PET,但第三降解活化能低于PET。
Taking polyethylene terephthalate(PET),polytrimethylene terephthalate(PTT)and polybutylene terephthalate(PBT)as research objects,the influence of methylene content on the glass transition temperature,melting crystallization behavior and cold crystallization behavior of the polyesters was investigated with a differential scanning calorimeter.Their crystallization physical constants were calculated by Avrami equation and Arrhenius equation.The thermal stability of PET,PTT and PBT was analyzed by thermogravimetric analysis.The results showed that the glass transition temperature of PET was 77.24℃while PTT and PBT had no obvious glass transition;their melting points decreased and the cold crystallization peak temperatures increased correspondingly when the methylene content increased in the sequence of PET,PTT and PBT;PTT had two cold crystallization peaks at 67.8 and 192.0℃;the melting crystallization behavior of the three polyesters all accorded with Avrami equation;the melting crystallization enthalpy and Avrami index increased and the semi-crystallization time decreased correspondingly,and the non-isothermal crystallization kinetic constant changed little after correction when the methylene content increased in the sequence of PET,PTT and PBT;PET,PTT and PBT all exhibited the degree of cold crystallization lower than the degree of melting crystallization,i.e.,the degree of cold crystallization was about 70%,10%and 7%of the degree of melting crystallization,and the cold crystallization rate increased in order;the thermal stability of the polyesters became worse corresponding to the sequence of methylene content from high to low;the thermal degradation of these three polyesters can be divided into three stages,and as compared with PET,PTT and PBT had the lower initial decomposition temperature,the higher first and second degradation activation energy and the lower third degradation activation energy.
作者
钱亚杰
曹利敏
QIAN Yajie;CAO Limin(Jiangsu Union Technical Institute at Yixing,Yixing 214206)
出处
《合成纤维工业》
CAS
2020年第1期50-54,共5页
China Synthetic Fiber Industry
