Mechanical Testing and Structural Characterization of Hydrostatically Extruded Polymers. I. Effects of Hydrostatic Extrusion on Subsequent Mechanical Behavior

抄録

Crystalline and amorphous polymers were hydrostatically extruded at room temperature with pressures up to 4 kilobars. Polymers studied include polyethylene, polypropylene, nylon, polyacetal, polyvinylchloride, ABS-co-polymer, polymethylmethacrylate and polycarbonate. Within the range of reduction percentages studied, 20-85%, the extention showed higher flow stress and lower elongation than the starting materials except PMMA: Fourfold increase in elongation with essentially unchanged flow stress was observed with the amorphous polymers. Dimensional stability of the crystalline extrusion at room temperature and also at 100°C decreased with an increasing reduction percentage and reached a minimum at 60% reduction, followed by an increase with higher reduction. On the other hand, with the amorphous polymers, the higher the reduction percentage, the poorer the dimensional stability. A linear relation was established between the extrusion pressure and the extrusion ratio. The polymers were also tested for compression, bending, specific gravity and hardnees, and correlation among the test results was discussed under assumption of a possible structural change due to hydrostatc extrusion.