DRAWING OF ULTRAHIGH MOLECULAR-WEIGHT POLYETHYLENE SINGLE-CRYSTAL MATS - THE CRYSTALLINITY

Single-crystal mats of ultrahigh-molecular-weight polyethylene can be drawn uniformly to high draw ratios after the necking process is completed. The dynamic mechanical modulus of the drawn mats increases markedly during the uniform drawing stage. The structural changes induced by the uniform drawing at 100 degree C have been followed by wide-angle and small-angle x-ray scattering, infrared absorption, differential scanning calorimetry, and birefringence. The results suggest that the uniform drawing after necking destroys the two-phase structure made up of alternately stacked crystalline and amorphous regions and then reorganizes it into a single-phase crystalline structure.