EFFECT OF PAN-MILLING STRESS ON CRYSTAL STRUCTURES OF HIGH DENSITY POLYETHYLENE

A detailed study was performed on the crystal structures of pan-milled high-density polyethylene (HDPE) usingdifferential scanning calorimetry (DSC) and X-ray diffraction. The crystallinity of HDPE first decreased slightly, followed bya gradual increase with increasing milling times. Monoclinic crystals appeared after 4 cycles of milling. With increasingtimes of milling, the proportion of monoclinic crystals increased significantly while the proportion of orthorhombic crystalsdecreased gradually. With increasing times of milling, the crystallite size of orthorhombic form decreased greatly, while thesize of monoclinic crystallites kept almost constant during milling.