EVA装置生产的LDPE结构与加工性能研究

Structure and Processing Properties of LDPE Produced by the EVA Plant

分析了乙烯-醋酸乙烯共聚物(EVA)装置上生产的低密度聚乙烯(LDPE)A与市售同类料LDPE B的差异,指出EVA装置因装置保护带来聚合工艺的差异,长、短支链支化作用降低,链段拓扑结构及立构规整性的差异可能是LDPE A熔体流动速率、密度等宏观物性偏低的主要原因;其短支链多、分子链均方回转半径小可能是LDPE A相对分子质量、结晶度等微观物性偏低的主要原因。EVA装置因三峰运行生产的LDPE A与同类料LDPE B相比,薄膜制品光学性能优,摩擦系数低,拉伸性能、加工流变性能、熔融温度相当,即聚合工艺的调整未对制品性能产生负面影响。

The difference between low density polyethylene(LDPE)A produced on ethylene vinyl acetate copolymer(EVA)plant and LDPE B of the same kind on the market was analyzed.It is pointed out that the difference in polymerization process caused by EVA device protection,the reduction of long and short branched chain branching,the difference in chain segment topological structure and tacticity may be the main reasons for the low macro physical properties of LDPE A such as melt flow rate and density.The main reasons for the low relative molecular mass,crystallinity,and other microscopic properties of LDPE A may be its large number of short branched chains and small mean square radius of rotation of molecular chains.Compared to LDPE B of the same material,the EVA plant produces LDPE A with three peak operation,the optical properties of film products are excellent,the friction coefficient is low,and the tensile properties,processing rheological properties and melting temperature are equivalent.That is to say,the adjustment of the polymerization process has not a negative impact on the product performance.