聚碳酸酯Fries重排与流变行为的关联研究  

Effects of Fries Rearrangement on Rheology of Polycarbonates

作　　者：徐佳鸿 王新宇 严圣迪 林宇[1] 吴国章[1] XU Jia-hong;WANG Xin-yu;YAN Sheng-di;LIN Yu;WU Guo-zhang(Shanghai Key Laboratory of Advanced Polymeric Material,School of Materials Science and Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[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

出　　处：《高分子通报》2023年第7期861-870,共10页Polymer Bulletin

摘　　要：系统考察了双酚A型聚碳酸酯(PC)的分子量、残留单体、端基种类和含量、Fries重排结构与毛细管流变行为的内在关联。研究发现,270℃下PC分子链没有明显的热氧降解,改变端羟基含量、封端基种类、残留单体含量也不会对降解产生显著影响,流变测试非常稳定。流变行为呈现典型的剪切变稀效应,但是在低剪切区没有看到牛顿流体特征,黏度总是随剪切速率降低而出现不同程度的升高。进一步研究表明,低剪切区的非牛顿流动指数n与PC分子量和测试温度没有关系,但是随Fries重排结构含量的增加而线性下降。酯交换法PC由于在聚合过程中经历了长时间的高温和真空环境,Fries重排结构含量较高,因此n值明显小于光气法PC,但前者具有较高的熔体强度和黏流活化能。The influences of molecular weight,residual monomer,end-group type and content,Fries rearrangement structure on capillary rheology of bisphenol A polycarbonates(PC)were systematically investigated in this study.No obvious thermo-oxidative degradation was observed and changes in the end-hydroxyl content,capping type and residual monomer did not deteriorate the degradation of PC chains,suggesting that rheological tests carried out near to 270℃are stable and repeatable.A typical shear-thinning effect was found in the viscosityshear rate curves without accompanying a Newtonian characteristic in the zero-shear-rate region.At the low shear-rate region,the viscosity increases with decreasing the shearing rate to different extents for different PCs.Further studies revealed that the non-Newtonian flow index n in the low shear-rate region remains constant for PC melts with different molecular weights and different testing temperatures.It decreases linearly with the increase of the content of Fries rearrangement structure involved in the PC chains.As PCs fabricated by the melt transesterification have to experience high temperature and high vacuum environment during the long polymerization process,they involve many Fries rearrangement-derived heterogeneous structure.This should be the reason why the n value is significantly lower than that of the phosgene PC,thus leading to higher melt strength and flow activation energy.

关 键 词：聚碳酸酯 异质结构 FRIES重排 流变 

分 类 号：TQ323.41[化学工程—合成树脂塑料工业]