Takashi Tagawa

Application of the high resolution SEM to the fine structure study of polyethylene

Abstract To examine the applicability of high resolution scanning electron microscopy to the field of fine structure study of polymers, a fine lamellar structure on the melt extruded polyethylene films has been observed using four types of commercially available SEM; (a) usual surface SEM with a tungsten hairpin cathode gun, (b) TEMSCAN type SEM with a tungsten hairpin cathode gun, (c) FESEM with a cold type field emission gun, and (d) TEMSCAN with a LaB6 cathode gun. A fine lamellar crystal of 10nm in thickness, which is composed of folded molecular chains and exists on polymer block surfaces, has been hitherto observable only by the replication technique. SEMs of type (a) and (b) can resolve the lamellar stacks but not a single lamella. The single sheet of lamella is observable with the SEMs of type (c) and (d) as a step on the crystal surface. These high resolution SEM images are compared with that of replicas and their merits are discussed.

Changes in the fold content due to drawing and annealing of polyethylene

Abstract The fold content of polyethylene, which varies with drawing and/or annealing, was evaluated by an IR method. Solution-grown n-paraffin single crystals are assumed as a standard material containing no folds, while solution-grown single crystals of polyethylene are assumed to contain one unit of fold content. In preparing mixtures of these two standard materials, the following equation is obtained: A1304—0.49A1350 = 0.14Cf A1304 and 0.49A1350 are the absorbances of the IR band at 1304 and 1350 cm-1, respectively. The fold contents (Cf of polyethylene specimens prepared under various conditions are estimated in terms of this equation. In the drawing process of polyethylene films, Cf decreases abruptly in the region of draw ratio of 2 ∼ 3 and gradually decreases with further drawing when drawn along the machine direction. The content of remaining folds are quite different between specimens drawn along the machine direction and those drawn transversely to this direction. This fact reflects the differe...

Histological and scanning electron microscopic study of tissue invasion of Bangerter nylon implant after enucleation.

An incidentally extirpated Bangerter-type nylon implant was examined by light microscopy and scanning electron microscopy. Three months after implantation, the implant was densely filled with tissues, which were shown by light microscopy to be muscle cells in the margin of the implant; the muscle cells were fixed there at the time of implantation, and fibrocytic cells were inside the implant.Scanning electron microscopy showed interlacing fibrous cells with erythrocytes and leukocytes among the nylon fibers, lamellar accumulation of fibrous cells around nylon fibers, and a smooth surface of the margin of the nylon implant. This invasion of fibrous cells into the nylon implant is one reason why the Bangerter type of nylon implant rarely falls out of the orbital socket.