SHISH-KEBAB CRYSTALS IN POLYETHYLENE INVESTIGATED BY SCANNING FORCE MICROSCOPY

Ultra-thin, highly oriented polyethylene (PE) films drawn from the melt have been investigated using scanning force microscopy (SFM) to study their surface morphology. The results obtained from SFM measurements exhibit the lamellar morphology and evidence for extended chain crystals of the films. Morphological defects, such as structural thickness modulations of lamellae and steps on lamellar crystals of less-than-or-equal-to 1 nm height, were obtained. The fact that the lamellar crystals protrude out of the film surface is explained by a combination of film processing and crystal growth effects. On a molecular scale, high resolution SFM investigations of the crystalline parts of the film show extended PE chains with an intermolecular distance repeat of 0.56 +/- 0.1 nm.