聚对苯二甲酸乙二醇酯（PET）的相对分子质量及其分布是影响其聚合与加工工艺的关键参数。基于六氟异丙醇（HFIP）可溶解绝大多数聚酯类聚合物的特点，使用HFIP作为凝胶渗透色谱仪的流动相，测试PET的相对分子质量及其分布。通过聚甲基丙烯酸甲酯（PMMA）窄标样建立校正曲线，测试PET在不同溶解温度与时间下相对分子质量及其分布，分析其相对标准偏差（RSD）。结果表明：溶解温度为20 ℃，溶解时间为8 h是PET的最佳溶解方案。干燥对比实验发现，HFIP溶解PET，样品无须干燥处理，溶解条件温和，可避免因干燥不充分和溶解温度过高导致PET降解。常规PET聚合工艺条件下，高真空聚合超过2 h后，PET相对分子质量增长变得缓慢，不同的聚合釜与聚合工艺会导致PET相对分子质量分布存在差异，且PET相对分子质量分布明显影响熔纺工艺的温度设置。

The relative molecular mass and its distribution of polyethylene terephthalate (PET) are key parameters affecting its polymerization and processing technology. Based on the characteristic that hexafluoroisopropanol (HFIP) can dissolve most polyester polymers, the relative molecular mass and its distribution of PET were measured by using HFIP as the mobile phase of gel permeation chromatography. The calibration curves were established by narrow standard samples of poly(methyl methacrylate) (PMMA). The relative molecular mass and its distribution were measured at different dissolution temperatures and time, and the relative standard deviation (RSD) was analyzed. The results show that the optimal dissolution scheme for PET is a dissolution temperature of 20 ℃ and a dissolution time of 8 h. Drying contrast experiment show that HFIP dissolves PET without drying treatment, and the dissolution conditions are mild, which can avoid PET degradation caused by insufficient drying and high dissolution temperature. Under the conventional PET polymerization conditions, the relative molecular mass of PET increases slowly after high vacuum polymerization for more than two hours. Different polymerization kettles and polymerization processes will lead to differences in the relative molecular mass distribution of PET, and the relative molecular mass distribution of PET obviously affects the temperature setting of melt spinning process.