Feb 2024
Theo A. Tervoort, André Brem and Fotis Christakopoulos
Abstract
Cutting-edge high-performance polyethylene (HPPE) fibers boast a density nearly identical to that of water, while combining a remarkable stiffness of approximately 110 GPa (which is half that of steel) with an impressive strength of about 4 GPa (more than twice that of steel). These extraordinary attributes make HPPE fibers indispensable in a wide range of applications, spanning from advanced bulletproof clothing to the delicate operation of raising a sunken ferry off the coast of Italy, protecting a fragile ecosystem.
To achieve these exceptional properties, a near-perfect macromolecular alignment is essential, which is accomplished through a large-scale uniaxial solid-state plastic deformation process at elevated temperatures, applied to solution-spun ultra-high molecular weight polyethylene (UHMWPE) precursor fibers. This process is commonly referred to as the "ultra-drawing process."
In this presentation, the large-strain nonlinear elasto-viscoplastic modeling of the ultra-drawing process will be discussed in detail. This will include an in-depth examination of the role of viscous strain hardening versus entropic hardening. Particular focus will be on the analysis of the maximum attainable plastic draw ratio in relation to variables such as strain rate, temperature and precursor concentration.
Bio
Theo Tervoort received his engineering degrees in Chemical Engineering (MsC, 1987) and Mechanical Engineering (PhD, 1996) at the Eindhoven University of Technology in the Netherlands, and became a Lecturer at the same university in 1987. In 1996 he started as senior research associate in the Polymer Technology Group at the Materials Department of the ETH Zürich, where he was appointed Ad Hominem Professor in 2010. His fields of research include mechanical and optical properties of polymers and polymer processing. Theo Tervoort is co-author of 94 peer-reviewed papers, and co-inventor on more than 20 patents (7 patent families) in the areas of processing and properties of polymeric materials, most of which have led to commercial applications.