Design and Comparison of Conventional Single Screw and Barrier Flight Screws for Metallocene and Ziegler-Natta Polyethylene

• Main Authors: Lee Pi-Chun, 李璧君
• Other Authors: Jiann-Shing Wu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/21009265916181442698

碩士 === 國立交通大學 === 應用化學系 === 89 === Making film is an important m-PE application. The film has good physical properties. But it’s difficult to be processed because that the molecular weight distribution of m-PE is narrow. The narrow molecular weight will be caused a low melt strength and high viscousity. Due to the poor melt strength of m-PE, the screw must be designed properly to avoid the overheat of melt. Computer simulation combined with Taguchi method is the most efficient method for finding the optimal geometry of the barrier screws. It’ll economize the developed time and improve the steady process. The optimal screw geometry of Single Screw ,Maillefer, Barr, Double channel Barr, Dray & Lawrence, Kim and Ingen Housz , with m-PE and ZN-PE as the processing material, can be determined, base on the length of melting zone , temperature difference of last channel section and screw pressure. Subsequently, the effect of processing conditions on the screw performance, such as solid bed velocity, melt film thickness, barrier clearance thickness, melting efficiency, melting rate per unit length, the length of melting zone, pressure build-up, and bulk temperature were discussed. Finally, the simulation results were compared with the experimental results to identify the accuracy of the simulation models.