耐高温聚酰胺PA10T的GPC测试方法

通过N–酰基化反应对聚对苯二甲酰癸二胺(PA10T)耐高温聚酰胺进行前处理,使其在常温下能够良好地溶解于极性溶剂中,进行凝胶渗透色谱(GPC)测试。研究发现,N–酰基化反应条件为:三氟乙酸酐(TFAA)与PA10T的物质的量之比为2.0、反应时间为24h,可稳定得到接枝率为75%的N–酰基化产物(PA10T-TFAA)。由于PA10T-TFAA在GPC流动相四氢呋喃中的流体力学体积远大于聚苯乙烯标样,导致基于聚苯乙烯校正曲线的GPC测试分子量远高于样品的真实分子量。利用一系列不同分子量的PA10T样品,对GPC进行了宽分布校正。基于新的校正曲线,GPC的测试分子量与样品真实分子量误差可小于4%。结合PA10T分子量与特性黏度,拟合得到了PA10T的Mark-Houwink方程。该方程适用的分子量范围涵盖了所有商品化的PA10T产品,对于科学研究与生产实践具有重要的指导意义。

Gel Permeation Chromatography of High Temperature Polyamide PA10T

N-acylation pretreatment was performed on high temperature polyamide poly(decamethylene terephthalamide)(PA10T). The improvement of solubility in polar solvent enabled the gel permeation chromatography (GPC) test at room temperature. It is found that,when the ratio of amount of substance of trifluoroacetic anhydride (TFAA) to PA10T is 2.0 and the reaction time 24 h,the stable grafting ratio of about 75% can be achieved for the product of N-acylation (PA10T-TFAA). The hydrodynamic volume of PA10T-TFAA in tetrahydrofuran (THF) is much larger than that of polystyrene standard sample,causing the relatively large GPC testing molecular weight compared with the real molecular weight. GPC calibration is then conducted via a series of PA10T samples with different molecular weight.According to the calibration result,the error between the GPC testing molecular weight and the real molecular weight is less than 4%. Mark-Houwink equation of PA10T is achieved based on the molecular weight and the inherent viscosity. The application range of this Mark-Houwink equation covers most of the commercial PA10T products,which has important significance on the production practice.