The relative molecular mass and relative molecular mass distribution of polytrimethylene terephthalate ( PTT) were determined at different polymerization time by multi-detector molecular exclusion chromatography ( SEC ) with hexafluoroisopro-panol as the solvent and 20 mmol/L sodium trifluoroacetate/hexafluoroisopropanol solution as the mobile phase at a column flow rate of 1 mL/min at 25℃.The number average relative molecular mass ( Mn ) of PTT was measured and compared by SEC , Ub-belohde viscometry and 1 H nuclear magnetic resonance ( 1 H-NMR) .The results showed that the relative moleulcar mass distribu-tion index of PTT was determined as 1.922, 1.980 and 1.950 and the Mn of PTT was determined as 29570, 57790 and 76240 by SEC method, 30790, 61270 and 82000 by Ubbelohde viscometry , and 31450, 60580 and 68870 by 1 H-NMR when the polymerization time was 0.5, 2.5 and 3.5 h, respectively; the correlation coefficient of Mn of PTT determined by these three methods was close to 1;SEC method was proved to be an efficient and convenient way to accurately determine the relative molec -ular mass and relative molecular mass distribution of PTT .%采用分子排阻色谱(SEC)法,利用SEC多检测联用仪,以六氟异丙醇为溶剂,以20 mmol/L的三氟乙酸钠的六氟异丙醇溶液为流动相,在柱流量为1 mL/min,温度为25℃条件下,测定了不同聚合时间制得的聚对苯二甲酸丙二醇酯(PTT)的相对分子质量及其分布,并与乌氏黏度计法及核磁共振氢谱(1H-NMR)法测定的PTT的数均相对分子质量(Mn)进行比较.结果表明:聚合时间分别为0.5,2.5,3.5 h的PTT,SEC法测得的Mn分别为29570,57790,76240,相对分子质量分布指数分别为1.922,1.980,1.950,乌氏黏度法测得的Mn分别为30790,61270,82000,1H-NMR法测得的Mn分别为31450,60580,68870;3种测试方法测得的PTT的Mn其相关系数接近1;SEC法可以准确地测定PTT的相对分子质量及其分布,方法高效、便捷.
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