Deformation Mechanics during Drawing of Ultra-High Molecular Weight Polyethylene Fibers

There has been extensive study of Ultra-high molecular weight polyethylene (UHMWPE) fibers owing to their remarkable tensile modulus and strength. It is understood that these properties are generated during the post drawing process. Questions remain however, regarding how the morphology of the polymer develops during processing, and how this leads to the observed properties. Basic information regarding strain rate, stress at failure, and the role of processing parameters is missing due to the difficulty of measurement with industrial processes. This information is critical to understanding the polymer response during drawing. In this study we use a modified extensional rheometer (VADER 1000) to perform the drawing process on a series of UHMWPE fibers spun at Drexel. We have shown previously that ASF crystalline structure is not limited to the isotropic states typically seen in literature. With the VADER 100, and this broad range of starting materials we can monitor true stress and strain throughout the draw, and discover the mechanical properties prior to, and at, the failure point. Small and wide-angle x-ray scattering is used investigate the crystalline morphology. With this information a fundamental understanding of the post-drawing will be developed.