Abstract
The crystal structure of drawn samples of high density polyethylene was investigated by using wide-angle X-ray scattering (WAXS) with CoKα and MoKa radiations. HDPE films with fiber-like morphology and constrained to a constant length on heating were studied in the range from room temperature to 158[ddot]C. Orthorhombic-hexagonal phase transition, which was previously reported only for UHMWPE fibers, was also proved to exist in moderate molecular weight HDPE drawn films. Differently from the orthorhombic phase, which melts at 129[ddot]C, the hexagonal phase formed melts at 158[ddot]C. A new hexagonal reflection with interplanar distance 2.139(7) Å, indexed as (101), is reported.