接枝率对N-烷基化聚对苯二甲酰对苯二胺性能的影响

Effect of grafting rate on the properties of N-alkylated poly(p-phenylene terephthalamide)

聚对苯二甲酰对苯二胺(PPTA)纤维是一种高性能纤维,因难溶于普通有机溶剂而使其应用受到较大程度限制。针对PPTA溶解性差的的缺陷,本文通过控制溴乙烷的量制备了不同接枝率的N-烷基化PPTA聚合物,并系统地研究了接枝率对PPTA结构和性能的影响。分别用傅立叶红外光谱分析(FT-IR)、核磁共振(NMR)、凝胶色谱仪(GPC)、基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)、X射线衍射仪(XRD)和热重分析(TGA)对PPTA聚合物和N-烷基化PPTA聚合物进行性能测试与分析,结果表明:烷基化反应不会破坏PPTA主链,随着接枝率越高,N-烷基化PPTA聚合物溶解性越好,但结晶度和热稳定性受到一定影响。越高接枝率对N-烷基化PPTA的溶解性的改善效果越好,这有助于工业上准确测试分子量及分子量分布。

Poly（p-phenylene terephthalamide）（PPTA） is a high-performance fiber, however, its application is limited because it is difficult to dissolve in ordinary organic solvents. In this paper, N-alkylated PPTA polymer with different grafting rates were prepared by controlling the amount of bromoethane for the poor solubility of PPTA, and the effect of grafting rate on the structure and properties of PPTA was systematically studied. The original PPTA and N-alkylated PPTA with different grafting rate were characterized by Fourier transform infrared spectroscopy, Nuclear magnetic resonance spectroscopy, Gel permeation chromatography, Matrix-assisted laser desorption/ionization time of flight mass spectrometry, X-ray diffraction and Thermogravimetric analysis. The experimental results show that the alkylation reaction does not destroy the main chain of PPTA.With the increase of grafting rate, the solubility of PPTA is improved, whereas crystallinity and thermal stability are reduced. The higher grafting rate is, the better effect of improvement of the solubility of the N-alkylated PPTA is, which helps to accurately test the molecular weight and molecular weight distribution in the industry.