Injection molding and injection compression molding of ultra-high molecular weight polyethylene: Minimized thermal degradation and delamination layer formation

Ultra-high molecular weight polyethylene (UHMWPE) in powder form was processed using injection molding (IM) with different cavity thicknesses and injection-compression molding (ICM). Tensile tests and impact tests showed that the ICM samples were superior to those of IM. Increased cavity thickness and ICM were helpful for improving the mechanical properties due to effective packing of the material. A delamination skin layer (around 300 µm thick and independent of cavity thickness) was formed on all IM sample surfaces while it was absent in the ICM samples, suggesting two different flow behaviors between IM and ICM during the packing phase.