改性共聚酯的化学结构及热降解性能

Chemical Strutures and Thermal Degradation Properties of Modified Copolyesters

在5 L聚合装置上,成功合成了一系列用间苯二甲酸乙二醇酯-5-磺酸钠(SIPE)和聚乙二醇(PEG)改性的共聚酯(MECDP)。核磁氢谱(1H-NMR)的测试结果表明:聚合物大分子中的对苯二甲酸(PTA)、PEG、SIPE的摩尔比与其投料比基本相符;共聚酯分子链的化学结构,与设想的分子链结构较好地吻合。热重分析仪(TGA)试验结果表明:在氮气和空气的氛围里,热降解温度(T)d均随着PEG质量分数的增加而下降;在空气氛围里的热降解,比在氮气氛围内的热降解更容易发生;在氮气氛围里的TGA曲线,只有一个热失重平台,而在空气氛围里的TGA曲线,有两个热失重平台。特性黏度变化的测试结果表明:PEG的质量分数越高,干燥温度越高,干燥时间越长,共聚酯的特性黏度值变得越小。

A series of copolyesters based on poly（ethylene terephthalate）（PET） were successfully prepared with sodium-5-sulfo-bis-（hydroxyethyl）-isophthalate（SIPE） and poly（ethylene glycol）（PEG） units as modifiers in 5 L reactors.Their chemical structures were characterized by 1H-NMR,and results showed that the actual molar ratio of PTA ∶PEG ∶SIPE were basically consistent with the relative feed ratio.The chemical structures were better accordant with the expected structures of them.Thermal properties of these copolyesters under different conditions were characterized by TGA.Experimental results indicated that thermal degradation temperature（Td） gradually reduced with the PEG content increasing.The results also indicated that the thermal degradation under oxygen conditions happened easily compared to that under nitrogen conditions.The TGA curves under nitrogen atmosphere had only one weight-loss stage,while the curves under oxygen atmosphere owned two weight-loss stages.Experimental results of the intrinsic viscosity indicated that the intrinsic viscosity decreased when the drying temperature was increased,or the drying time was prolonged,or more PEG units were incorporated into molecular chains.