【作者】 周新慧；

【导师】 马秀清；

【作者基本信息】 北京化工大学 ， 机械设计及理论， 2007， 硕士

【摘要】 在啮合同向双螺杆挤出机对高聚物共混改性的加工过程中，螺杆构型是影响混合效果的一个重要因素。本文采用专业CFD(Computational Fluid Dynamics)软件POLYFLOW，对啮合同向双螺杆挤出过程中，导程为20mm的常规螺纹元件、错列角为60°的捏合盘元件、错列角为90°的捏合盘元件、错列角为120°的捏合盘元件、S型元件、齿形盘元件、六棱柱元件及非啮合多过程元件下的三维等温非牛顿流场进行了模拟计算，通过计算得到了各流场下的剪切应力场、停留时间分布及回流量，由此分析比较了各种螺杆元件的混合性能，结果表明：错列角为120°的捏合盘元件剪切作用最大，分散混合能力最强，而另外两种捏合盘元件和小导程常规螺纹元件也具有较好的分散混合能力。对于分布混合能力，由于物料在流经错列角为120°的捏合盘元件时回流量最大，在流经六棱柱元件时停留时间分布曲线拐点间的距离最大，因此这两种元件的分布混合能力很强。其它新型元件也具有较好的分布混合能力。对于模拟结果的正确性，本文通过实验进行了验证，同时对不同螺杆构型对两相不相容体系共混物混合效果的影响进行了深入研究。实验所研究的螺杆元件除模拟中用到的之外，还增加了错列角为30°、150°的捏合盘元件以及斜齿齿形盘元件。将所研究的这些螺杆元件分别置于双螺杆挤出机中的熔融段和熔体输送段，对实验结果进行了分析比较，结果表明：捏合盘元件具有较强的分散混合能力，更适于放置在双螺杆挤出机中的熔融段。S型元件具有较好的分布混合能力，同时由于其结构特点所引起的拉伸流动，增强了其分散混合能力，亦适于放置在熔融段。六棱柱元件、齿形盘元件、非啮合多过程元件具有较强的分布混合能力，置于熔体输送段将有利于得到分布均匀的制品。更多还原

【Abstract】 In the polymer compounding process, screw configurations are important factor influencing the mixing effect of the polymer blends in co-rotating twin screw extruder.In this paper, applied the professional package of Computational Fluid Dynamics, POLYFLOW, the flow field of different screw configurations for three-dimensional isothermal Non-Newtonian model in intermeshing co-rotating twin screw extruder were simulated. The screw elements included SE20/120, KB60/120, KB90/120, KB120/120, S, TME, FTX, NI-MPE. Shear-stress profile, residence time distribution and backflow rate were obtained. The mixing ability of different screw configurations was compared. KB120/120 had the greatest dispersive mixing ability for its powerful shear stress effect. KB60/120, KB90/120 and SE20/120 also had significant effect on dispersive mixing. For distributive mixing ability, KB120/120 and FTX showed excellent performance on distributive mixing ability, because they had the greatest backflow and the widest distance between inflexions of RTD curve respectively. The other new type screw elements also had good distributive mixing ability.The accuracy of simulation results were verified by experimental studies. In addition, the influence of screw configurations on binary immiscible blend was got further investigation. Besides screw elements employed in simulation, KB30/120, KB150/120, and ZME were added in experiment study. These screw configurations were located at either the melting section or the melt conveying section of co-rotating twin screw extruder. The results showed that: kneading block elements had significant effect on dispersive mixing ability, which was more suitable for being located at melting section than melt conveying section of co-rotating twin screw extruder. S element provided good performance on distributive mixing. In addition, because of its structure feature which resulted in elongational flow enhanced the dispersive mixing ability, so it is suitable for being located at melting section. FTX element, TME or NI-MPE had significant effect on distributive mixing ability. They were located at melt conveying section of co-rotating twin screw extruder would obtain homogenization products.更多还原