Surface structure of polyethylene crystals as revealed by surface decoration. II. Electron-microscopic detection of mobilizable surfaces

Abstract

The paper is the first step in the application of the gold decoration technique described in Part I to the electron-microscopic study of the nature of the fold surface of polyethylene single crystals. It was observed that different areas of the same crystal layer display different decoration densities. It appears that this is due to residual solvent which is retained to different extents by different crystal portions. This assumption is substantiated by the salient observation that the initially slight decoration differences are much accentuated by deliberate flooding of the decorated crystals with a swelling agent. The inference is that the swelling liquid mobilizes some loose elements along the crystal surface, and, consequently, the differences within the same crystal reveal a variable crystal surface as regards surface looseness. With the new technique we are now able to describe and follow these phenomena as a function of the relevant variables. Within the confines of the present work it has already become apparent by this test that, from the usual commercial polymer, surfaces with least looseness are formed toward the end of the crystallization.