Hydrostatic Cold Extrusion of High-Density Polyethylene

• Published in: KOBUNSHI RONBUNSHU Vol. 38; no. 5; pp. 315 - 322
• Main Authors: ONOGI, Shigeharu, MATSUMOTO, Kiyoichi, KAWAMURA, Haruo, KUBA, Kazuo, UTSUMI, Nobuo, MATSUSHITA, Tomiharu
• Format: Journal Article
• Language: Japanese
• Published: The Society of Polymer Science, Japan 25.05.1981
• Subjects: Characteristic of Extrusion; Die-Swell; Fine Structure; High-Density Polyethylene; Hydrostatic Cold Extrusion
• ISSN: 0386-2186; 1881-5685
• DOI: 10.1295/koron.38.315

The hydrostatic cold extrusion was carried out on high-density polyethylene (HDPE) with a die having die-angle of 45°, and characteristics of the extrusion as well as the fine structure of extruded HDPE were examined. Main results obtained are summerized as follows. (1) The die-swell appears not only during extrusion but also over a few months after the extrusion. (2) The extrusion proceeds at comparatively high rates at an initial stage, but the rate decreases gradually until the steady-state is reached. (3) An equation derived by Pugh and Low for the hydrostatic extrusion of metals can be applied to HDPE extruded at low or high processing ratio. (4) The crystalline orientation of hydrostatic extrudates is typically uniaxial. (5) The degree of crystallinity and size of crystallites decrease with increasing extrusion ratio, because of break down and disintegration of the folded-chain structure.