The superstructure of melt‐crystallized polyethylene. I. Screwlike orientation of unit cell in polyethylene spherulites with periodic extinction rings

Abstract

Abstract The ringed structure in polyethylene spherulites was investigated by an x‐ray microdiffraction method. A spherulite with extinction rings whose interval is about 50 μ was observed when viewed under the polarization microscope. An asymmetric x‐ray diffraction fibrous pattern about the b axis was obtained for this specimen. This indicates that in the area of spherulite (several microns in diameter) the unit cells are never randomly oriented around a common b axis but have nearly similar orientations. A series of micro‐diffraction patterns was obtained at intervals of 13 μ (about 1/4 the extinction fringe interval), and it was shown that the unit cells have screwlike orientations with their common b axis along the spherulite radius. The distance corresponding to one‐half the pitch of the screw is just in accordance with the extinction ring interval.