Electron Microscopy of Crystalline Polymers

Abstract

This thesis describes the micro-structu re of crystalline polymers, particularly as revealed by electron microscopy, and also the effect of £he electron beam on the radiation sensitive specimens under various conditions.Polymer single crystals grown from dilute solution were used o for the radiation damage studies, as they are thin (100 A), and a 8 single preparation may contain 10 crystals of uniform properties.Preparations of polyethylene (PE), polyoscymethyl ene (PQM)» poly 4*me thy lpentene-1 (P4MP), nylon 6 and polyethylene oxide were characterized in the transmission electron microscope, confirming previous work for the most part. The scanning electron microscope, operating in its normal mode, showed even the thinnest single crystals clearly, when they were sedimented onto a metal coated substrate.Attempts to observe the 3-D pyramidal structure of PE single crystals j were unsuccessful* The crumpling seen when crystals floating on glycerol, or freely suspended from a En£ mesh, are irradiated in an electron microscope indicates that even if the structure were preserved, by freeze drying or however, it would be difficult to observe. Thicker, complex, crystals seemed more stable in the scanning electron microscope, and cannot be seen well in the transmission microscope.A Chart recorder, picoammeter and special faraday cup were fitted to a Siemens Elmiskop i for accurate beam current measurements , and dynamic recording of the varying intensity of polymer crystal images.