PEG/PET嵌段共聚酯的流动行为研究

Study on flow behavior of PEG/PET block copolyesters

为研究聚乙二醇(PEG)与聚对苯二甲酸乙二醇酯(PET)嵌段共聚酯(PEG/PET)的高分子稀溶液和熔体流动行为,从而为改性共聚酯的配方设计、加工应用提供参考,采用毛细管流变仪、高温凝胶色谱仪(GPC)研究PEG/PET稀溶液及熔体的流动行为,分析嵌段共聚酯的分子链长度、柔顺性以及分子链的形态。通过对比不同PEG含量嵌段共聚酯的流变性能,计算了共聚酯的非牛顿指数、黏流活化能、结构黏度指数。结果表明,嵌段共聚酯中PEG含量增加,共聚酯稀溶液的流经时间、嵌段共聚酯特性黏度呈现线性上升的趋势,嵌段共聚酯的相对体积呈现降低的趋势,PEG的引入会使嵌段共聚酯分子量增加,柔顺性提高。各样品均属于典型的假塑性流体特性。当加工温度超过288℃后,温度对于改善嵌段共聚酯熔体流动性的作用有限。相比常规聚酯,嵌段共聚酯的非牛顿指数n值提高0.05以上,黏流活化能增加,结构黏度指数降低。

In order to study the polymer dilute solution and melt flow behavior of PEG/PET block copolyesters,and provide reference for the formulation design,processing and application of modified copolyesters,the flow behavior of dilute solution and melt of PEG/PET was studied by capillary rheometer and high temperature gel chromatograph(GPC),and the molecular chain length,compliance and morphology of block copolyester were analyzed.By comparing the rheological properties of block copolymers with different PEG contents,the non-Newtonian index,viscosity activation energy and structural viscosity index of copolymers were calculated.The results show that with the increase of PEG content in block copolyester,the flow time of dilute solution and the intrinsic viscosity of block copolyester increase linearly,while the relative volume of block copolyester decreases.The introduction of PEG can increase the molecular weight of block copolyester and improve its flexibility.All samples have typical pseudoplastic fluid characteristics.When the processing temperature exceeds 288℃,temperature has limited effect on improving the fluidity of block copolyester melt.Compared with conventional polyester,the non-Newtonian index n value of block copolyses increases by more than 0.05,the viscosity activation energy increases,and the structural viscosity index decreases.