茂金属线性低密度聚乙烯结构-流变性能-加工行为关系的研究

Relationships between Polymer Structure and Rheological Properties of Metallocene LLDPE and Their Influences on Film Blowing Processing

考察了几种茂金属线性低密度聚乙烯和传统线性低密度聚乙烯结构（诸如相对分子质量、分布短支链和长支链）和熔体流变性能间的关系（包括动态粘度、储能与耗能模量、松驰谱与松驰谱分布宽度指数、零切粘度、粘流活化能、以及表观剪切粘度、临界剪切速率、熔体强度等）。研究了这些性能对吹塑薄膜加工行为的影响。聚合物主链上存在长支链改变流变特性。在加工性能差的茂金属线性低密度聚乙烯中加入１０％的线性低密度聚乙烯能显著改善其加工性能，而薄膜物理机械性能降低不多。

Various mLLDPE and traditional LLDPE with about the same molecular weight were tested to evaluate the effect of polymer structure(MW,MWD,short and long chain branches etc )on melt rheological properties,including dynamic viscosity,storage and loss moduli,relaxation spectrum and relaxation spectrum index(RSI),zero shear viscosity,activation energy of viscous flow,apparent shear viscosity,critical shear rate for melt fracture,and melt strength Influences of these properties on the processing behavior during film blowing were also studied The presence of long chain branches on polymer backbone changes its rheological properties.Processing properties can be improved by blending 10% LDPE with mLLDPE without much influence on physical properties of the film