叶片挤出机中聚丙烯熔融过程的可视化研究

Visualization Research on Polypropylene Melting Process in Vane Extruder

通过自主研发的组装式叶片挤出机,采用动态可视化技术在线观察不同尺寸的结晶型聚丙烯的熔融过程,分析结晶型聚合物在叶片挤出机中的熔融规律和机理.研究表明:聚丙烯在叶片挤出机中的熔融过程分为全固体、富固体和富熔体3个阶段;在全固体和富固体熔融阶段,固体颗粒产生很大的塑性变形,固体颗粒在热传导和塑性耗散热的共同作用下熔融;而在富熔体熔融阶段,可以明显观察到固体颗粒的熔融,熔融过程主要受熔体黏性耗散热的影响;熔融所需VPCU组数受最难融固体颗粒(最大固体颗粒)控制,小颗粒物料比大颗粒物所需VPCU组数少.

The melting process of crystalline polypropylene with different sizes was observed on line by means of dynamic visualization technique through a self-developed assembled vane extruder, and the melting law and mechanism of the polymer were also analyzed. The results show that （ 1 ） the melting process in the vane extruder includes three stages, namely the full-solid melting stage, the solid-rich melting stage and the meh-rieh meting stage; （2） in the full-solid and the solid-rich melting stages, solid pellets may generate large plastic deformation, and the melting process is dominated by heat conduction and plastic dissipation heat, while in the melt-rich meting stage, the melting process of solid pellets can be obviously observed, and the melting process is dominated by viscous dissipation heat of the melt; and （3） the number of VPCU groups in the melt-rich meting stage is controlled by the hardest melting pellets （namely the largest pellets）, and more VPCU groups are required for the melting of small pellets.