Extensional flow‐induced crystallization in polyethylene melt spinning

Polyethylene was spun into a heated chamber, with the spin‐line temperature controlled in the range of 90–120°C. Within narrow limits, the stretch rate of the fiber was also controlled. Spin‐line and crystallization onset conditions were characterized. Characteristics of fibers as‐spun were measured via wide‐angle x‐ray scattering (WAXS), density, scanning electron microscopy, and differential scanning calorimetry. Spin‐line data indicate that elongational flow enhances crystallization rate and that time under spin‐line conditions is an important parameter. Analysis of WAXS data shows a typical “ b ‐axis radial” orientation, the details of which change with spin‐line parameters. This orientation is consistent with growth of lamellar crystals on extended‐chain fibrils (shishkebab model). Other physical data are also consistent with this microstructure. Microcamera x‐ray patterns show a similarity of microstructure generation in spinning and drawing.