Effects of ECAE on Plastic Deformation Behavior of Glassy Polymers
Shin'ya YOSHIOKA and Kinji TSUKAMOTO
Abstract:We examined applicability of equal channel angular extrusion (ECAE) to improvement of plastic deformability of glassy polymers. Polycarbonate (PC) and poly(methyl methacrylate) (PMMA) were extruded at various temperatures ranging from 50°C to just below the glass transition temperature through one of three equal channel angular dies (ECA-dies) having a pass angle 2φ of 90°, 120° and 150°. Both PC and PMMA could successfully be extruded at most of all conditions examined in this study, although PMMA could not be extrudable at temperatures below about 60°C. After processed through ECAE, extruded PC and PMMA were subjected to tensile test. It was found that ECAE lessened the tensile yield stress of the glassy polymers when extrusion was performed at a lower temperature and through an ECA-die with a larger pass angle 2φ. Plastic flow stress did not so much increase in polymers extruded through an ECA-die with a larger 2φ. Thus, ECAE at a lower temperature through a die with a larger pass angle 2φ was found to be effective to improve plastic deformability of glassy polymers. Key Words:ECAE, Glassy polymer, Polycarbonate, Poly(methyl methacrylate), Plastic deformation, Yield stress