PET-co-PEG共聚酯的制备及其结晶行为的研究

Preparation and crystallization behavior of PET-co-PEG copolyester

以对苯二甲酸、乙二醇、聚乙二醇(PEG)为原料,通过直接酯化-缩聚法制得不同PEG含量的共聚酯(PET-co-PEG),并用差示扫描量热(DSC)仪、X射线衍射(XRD)仪对PET-co-PEG的结晶性能进行了表征。结果表明:PEG的引入使得PET的玻璃化转变温度、冷结晶温度、熔点降低,且随着PEG添加量的增加,降低幅度增大,结晶过冷度和过热度增加,结晶变难;在118~178℃等温冷结晶过程中,PEG质量分数为15%的PET-co-PEG试样的Avrami指数为1.23~1.59,在等温结晶温度为148℃时,试样结晶速率最高,结晶速率常数达1.7 min^(-1),而在133℃结晶完全时试样的结晶度最高,XRD结果显示在133℃完成等温结晶时,衍射峰强度和结晶度最高,表现出与DSC测试结果类似的变化规律。

Polyethylene terephthalate-eo-polyethylene glycol （PET-co-PEG） copolyester with different PEG content was pre- pared by using terephthalic acid, ethylene glycol and polyethylene glycol via direct esterifieation-polyeondensation. The crystalli- zation behavior of PET-co-PEG was characterized by differential scanning calorimetry （ DSC ） and X-ray diffraction analysis （XRD）. The results showed that the introduction of PEG caused the glass transition point, cool crystallization temperature and melting point of PET to decrease, and the decrease extent was increased, the crystallization undercooling and superheating were also increased, and the crystallization behavior became difficult as the addition of PEG was increased ; the Arrami index of PET- co-PEG with 15% PEG by mass fraction was 1.23 -1.59 during the isothermal cool crystallization over 118 - 178℃, and the crystallization rate of PET-co-PEG was maximized and the crystallization rate constant reached 1.7 min - 1 at the isothermal crystal- lization temperature of 148℃ , and the crystallinity was maximized as the crystallization totally completed at 133℃. The XRD result showed that the diffraction peak intensity and the crystallinity were maximized as the isothermal crystallization completed at 133℃ , which agreed with the change regularity observed by DSC.