文献类型：期刊文献

中文题名：聚碳酸酯熔体在氮气环境中的增黏效应及其机理研究

英文题名：Studies on Viscosity and Chemical Structure Changes in Polycarbonate Melts under Nitrogen Protection

作者：姜雷[1];严圣迪[1];林宇[1];吴国章[1]

机构：[1]华东理工大学材料科学与工程学院,上海市先进聚合物重点实验室,上海200237

年份：2021

卷号：42

期号：3

起止页码：884

中文期刊名：高等学校化学学报

外文期刊名：Chemical Journal of Chinese Universities

收录：CSTPCD;;EI(收录号：20211410160029);Scopus;WOS:【SCI-EXPANDED(收录号:WOS:000627118700027)】；北大核心:【北大核心2020】；CSCD:【CSCD2021_2022】；

语种：中文

中文关键词：聚碳酸酯;熔体增黏;流变测试;凝胶化

外文关键词：Polycarbonate;Melt viscosity increase;Rheological measurement;Gelation

摘要：双酚A型聚碳酸酯(PC)在高温加工过程中容易降解,表现为黄变和黏度逐渐下降.本文研究结果表明,某些PC在N2气保护下有可能出现熔体增黏效应.借助动态流变实验研究了7种PC的熔体增黏行为,利用高效液相色谱(HPLC)和核磁共振波谱(NMR)分析了分子结构演变规律.结果表明,与光气法PC熔体黏度先下降后缓慢上升不同,酯交换法PC熔体随着检测时间的延长黏度上升,熔体强度增大,出现更严重的剪切变稀现象.分子结构表征证实,在无氧条件下PC分子链发生了支化或交联反应,形成了高分子量凝胶物.酯交换法PC在高温下的凝胶化速度比光气法PC高,导致低频区出现较高的剪切黏度.我们推测,端羟基含量可能是造成不同PC凝胶化差异的主要因素.
Bisphenol A polycarbonate(PC)tends to degrade during high-temperature processing,resultting in yellowing and a gradual decrease in viscosity.Here,we report that some kinds of PC melts have a viscosity increase effect under N2 protection.Seven grades of PCs were used to check the change in melt viscosity under high temperature in N2 by means of dynamic rheological measurements,and their evolutions in molecular structure were analyzed by high performance liquid chromatography(HPLC)and nuclear magnetic resonance spectroscopy(NMR).Results show that,unlike PCs synthetized by phosgene method where the viscosity of PC melts decreases firstly and later increases slowly,PCs synthetized by transesterification method present an increase in melt viscosity and melt strength with annealing time and exhibit serious shear thinning effect.Molecular structure characterization confirms that PC molecular chains are branched and cross-linked under anaerobic conditions,thus forming a high molecular weight gel.The gelation speed of PCs synthetized by transesterification method is higher than that of PCs synthetized by phosgene method,resulting in higher shear viscosity and melt strength in the low frequency region.We propose that the terminal hydroxyl content may be the main factor causing the difference in gelation of different PCs.