Rolling and roll‐drawing of ultrahigh molecular weight polyethylene reactor powders

Abstract

SYNOPSISUltrahigh molecular weight polyethylene (UHMWPE) reactor powders have been found to be processable in the solid state by the techniques of rolling and roll-drawing. Plates of compacted UHMWPE reactor powder were prepared below their melting points. These plates were then rolled at 124°C. The maximum uniaxial draw ratio (DR) obtained by multiple rolling was about 10. In additional experiments, rolled plates of a DR of 6 were further drawn by tensile stretching at a temperature of 135°C. The specimens prepared by rolling and by the two-stage draw were characterized by tensile measurements, differential scanning calorimetry (DSC) , and X-ray diffraction. Results show that, on rolling alone, the tensile modulus and tensile strength achieved were 3 GPa and 42 MPa, respectively, a t a DR of 9.6. The rolled plates were effectively drawn further to a total DR of 86. Such highly drawn films exhibited tensile moduli and tensile strength up to 81 and 1.3 GPa, respectively. A high crystallinity and high crystal orientation were also obtained by the two-stage draw.

Solid‐state compaction and drawing of nascent reactor powders of ultra‐high‐molecular‐weight polyethylene

“…The appearance of the double peaks has been observed in the thermal analysis of gel-spun UHM-WPE fibers, 22 whereas the sharp single endothermic peak has typically been observed in many conventional solid-state drawings of UHMWPE reactor powders. 8,9,23 The changes with increasing draw ratio in the SAXS patterns of the UHMWPE filaments made from the UHMWPE powder 30C_15P are illustrated in Figure 12. The first-order maxima in the SAXS reflections linearly decreased with increasing draw ratio and eventually disappeared at high draw ratios.…”

High-Performance Fibers

“…Other than films, precursors to high temperature draw were also evaluated. Powder rolling was studied in [102] resulting in fiber properties of 1.3 and 81 GPa for tenacity and modulus, respectively. Solid-state coextrusion of mats of polymeric powder from solution crystallization was studied in [103].…”