屏障混炼塑化单元加工聚合物塑化混合特征

Polymer Plasticizing and Mixing Characteristics Processed by Barrier Mixing-plasticizing Unit

针对叶片式挤出和注射成型加工设备中的屏障混炼塑化单元,应用流体动力学软件Polyflow对其加工聚合物的塑化混合特征进行模拟并与螺纹单元比较。结果表明:屏障混炼塑化单元熔体黏度沿单元周向转动方向逐渐降低,最大剪切速率曲线在螺纹单元的右方,混合指数以大于0.5的区域为主,分离尺度曲线与螺纹单元的相近,拉伸长度对数、拉伸速率和时均混合效率的曲线均在螺纹单元的上方。因此,屏障混炼塑化单元实现了对聚合物熔体的正位移输送,有利于聚合物塑化能力和混合效果的提高;屏障混炼塑化单元流场内物料以拉伸作用为主,对聚合物的拉伸作用要强于螺纹单元,有利于对物料分散混合效率的提高;屏障混炼塑化单元对聚合物的分布混合能力与螺纹单元相当,对聚合物的分散混合能力大于螺纹杆单元,采用屏障混炼塑化单元加工聚合物具有很好的混合质量和节能效果。

Using barrier mixing-plasticizing unit for vane extrusion and injection molding machines and fluid dynamic software Polyflow,polymer plasticizing and mixing characteristics was simulated,including the comparison with screw unit. The results showed that melt viscosity in barrier mixing-plasticizing unit along circular rotating direction decreased gradually, maximum shear rate curve located in the right side of screw unit,region mixing index with more than 0.5 was predominant, segregation scale curve was similar to screw unit, stretching length logarithm, stretching rate and time average mixing efficiency curves were all above screw unit. Therefore, barrier mixing-plasticizing unit could realize positive displacement transportation to polymer melt, and improve plasticizing ability and mixing effect. Tensile action on polymer in the flow field of barrier mixing- plasticizing unit was dominant and stronger than screw unit, which was beneficial to improve dispersive mixing efficiency. Distributive mixing ability of barrier mixing-plasticizing unit on polymer was equivalent to screw unit, but dispersive mixing ability was higher than screw unit. Better mixing quality and energy consumption effect could be obtained through adopting barrier mixing-plasticizing unit to process polymer.