Sayaka Yamada, Kazuhide Sekiyama, Shiori Watanabe, Kazuo Yamaguchi, Hideo Funahashi
Papers # 2018 Las-Vegas
Performance evaluation method of plastic mixers for high density polyethylene by using flow simulation is presented in this study. First, Mixing experiments were performed to find the mixing performance of mixers. Then, flow simulations using our original software in the mixers were carried out to know the important flow factors. It was found that appropriate residence time and stress is important. Furthermore, new mixer is introduced. The mixer has high performance and the result can be explained by same reason.
Bi-modal high-density polyethylene (HDPE) has become more popular in recent years, because it has both easier processability and higher mechanical strength. However, it is difficult to eliminate clusters derived by high molecular weight component. The cluster is called “gel” in this study. We compared gel elimination mixing performance of two types of our mixers, which are typically applied to high capacity processing of the bi-modal HDPE. One is counter-rotating twin screw continuous mixer LCM-H and the other is corotating twin screw extruder KTX. In mixing experiments, bi-modal HDPE for pipe grade with carbon black was used. From the results, it is found that LCM-H has better gel elimination performance than KTX. Furthermore, we performed partially filled numerical analyses around molten mixing zones to understand the physical meanings of experimental results. From the investigation, it is found that LCM-H has better gel elimination mixing performance than KTX because LCM-H gives gels larger stress and appropriate residence time than KTX. In addition, new generation counter rotating continuous mixer “LCM-IM (Intensive Mixing)” was introduced. From the experimental investigation, it is found that LCM-IM has better mixing performance than LCM-H. The numerical analysis and performance evaluation were also carried out and we realized again that LCM-IM has the best mixing performance because it has the effective residence time.