WAXS STUDY ON ORTHORHOMBIC CRYSTALLINE PHASES IN HOT-DRAWN HIGH-DENSITY POLYETHYLENE

The temperature dependence ill the range 23-135 degrees C of hot-drawn HDPE plates maintained free from contraction was investigated by WAXS and DSC. A specially designed cylindrical chamber was used for the WA XS patterns. The results confirm the coexistence of two populations of orthorhombic crystals which have different lattice and thermal behavi our. The crystal lattice parameter a show's expansion, while b exhibit s expansion lip to 90 degrees C, followed by contraction as the temper ature is raised to melting. On the other hand the c parameter is pract ically constant. (C) 1998 Elsevier Science Ltd All rights reserved.