Delamination-Free Injection Molding of Ultra-High Molecular Weight Polyethylene

Abstract

When ultra-high molecular weight polyethylene (UHMWPE) in powder form is injection molded, delami¬nation occurs near the skin of the parts. This layering defect hampers UHMWPE’s superior wear resistance and surface quality. The delamination layer is caused by a combination of excessive shear stress near the part surface and a high degree of molecular entanglement. A mold insulation method that delays the rapid cooling of UHMWPE, which serves to reduce the shear stress and improve polymer chain “interdiffusion” across the entangled chain bundles, was used to eliminate the dela¬mination layer. When the insulation layer thickness and mold temperature were optimized, the delamination layer was eliminated. The delamination-free parts showed UHMWPE’s superior impact resistance and tensile properties.

About the Speaker

Professor Lih-Sheng (Tom) Turng received his B.S. degree from the National Taiwan University, and his M.S. and Ph.D. degrees from Cornell University. He worked in the industry for 10 years before joining University of Wisconsin–Madison in 2000. His research encompasses injection molding, microcellular injection molding, nanocomposites, multi-functional materials, bio-based polymers, biomanufacturing, and tissue engineering. Professor Turng holds the Kuo K. and Cindy F. Wang Professorship and the Vilas Distinguished Achievement Professorship. He is the Co-Director of the Polymer Engineering Center at University of Wisconsin–Madison, a Fellow member of the Society of Plastics Engineers (SPE) and the American Society of Mechanical Engineers (ASME), and an Honored Service Member of the SPE. Professor Turng has published more than 265 journal papers and over 200 conference paper and presentations.