High elastic modulus polyethylene – A two-stage multi-axial rolling and orientation process

Abstract

In this study, we propose a novel two-stage solid-state processing technique to fabricate thin-oriented high-density polyethylene (HDPE) rods with enhanced mechanical properties. This unique solvent-free technology involves biaxial rolling (Stage 1) followed by a uniaxial orientation procedure (Stage 2). The oriented thin HDPE rods exhibit an impressive modulus of 37 GPa. This is a result of a complex, oriented composite structure containing crazes with a network of interlocking fibers. Surprisingly, the high-modulus thin rods were created under relative low uniaxial tensile orientation conditions having draw ratio of eleven. Gel-spun ultra-high-molecular-weight fiber processing requires orientations greater than thirty. A corresponding scaled hierarchical model was proposed to summarize the process-structure-property relationships. This study demonstrates a strategy for creating high-modulus polymeric materials via controlled solid-state processing.