Structure of extruded-blown film of high density polyethylene

Structure of the extruded-blown film of high density polyethylene was studied by X-ray diffraction, SEM, and SPM. Lamellar bundles were piled up along the extrusion direction and oriented perpendicular to the extrusion direction. Close observation by SPM revealed that one lamellar bundle which looked like a single lamella by SEM was actually composed of ca. 6 lamellae. We propose that formation of such lamellar bundles may be due to self-vibration by rubbing with a die during the extrusion of melt.