高分子量聚对苯二甲酸乙二醇酯中低聚物的提取及其表征

为研究高分子量聚对苯二甲酸乙二醇酯（HMW-PET）中低聚物的成分和含量及其对HMW-PET结晶和热学性能的影响，通过萃取法和沉淀法对纤维级PET、液相增黏和固相增黏HMW-PET产品及过程样中的低聚物进行提取，并借助超高效聚合物色谱和差示扫描量热仪对低聚物进行表征。结果表明：沉淀法可快速分离不同工艺产品中的低聚物，得到的低聚物种类较齐全；而萃取法准确性较高，重复提取偏差控制在3% 以内；不同工艺制备的HMW-PET产品低聚物含量存在明显差异；萃取的低聚物在246.6、310.7 ℃附近出现吸热峰，其中环状三聚体含量最高；纤维级PET 及HMW-PET经提取后冷结晶温度均升高，但纤维级PET 熔融焓降低，而HMW-PET熔融焓升高。

Extraction and characterization of oligomers fromhigh molecular weight poly(ethylene terephthalate)

In order tostudy the composition and content of oligomers extracted from high molecular weight poly(ethylene terephthalate) (HMW-PET) and its invluence on the properties of HMW-PET, theextraction and precipitation ofoligomers were performed on fiber-grade PET,solid-state polycondensation (SSP) and liquid-state polycondensation (LSP). The obtained oligomers were characterized byadvanced polymer chromatographyand differential scanning calorimetry. The results show that the precipitation process could separateoligomers quickly and completely. The extraction process canobtain oligomers with a good accuracy and less than 3%. The difference of oligomers content andcomponent is significant between SSP product and LSP products. The oligomers extracted show endothermic peaks at about 246.6 and 310.7 °C, respectively, and cyclic trimer accounts for the highest proportion in oligomers for all products. The cold crystallization temperature of fiber-grade PET and HMW-PET treated by extraction is increased. The melt enthalpy of fiber grade PET decreases by the extraction, while the enthalpy of HMW-PET become higher.