Simple shear plastic deformation behavior of polycarbonate plate II. Mechanical property characterization

It has been demonstrated in Part I of this research that the high degree of plastic deformation caused by the equal channel angular extrusion (ECAE) p rocess leads to a nearly uniform molecular orientation across the extruded polycarbonate (PC) plate. In this paper, the effectiveness of the ECAE proc ess in altering the mechanical property of PC is investigated. Significant improvements in flexural modulus and fracture toughness are observed, and a re found to be closely related to the ECAE-induced molecular orientation. M icroscopy observations of the fracture process show that the crack propagat ion direction is controlled both by the ECAE-induced molecular orientation direction and by the maximum principal stress direction, which results in t he formation of hackles. Potential advantages of ECAE for fabricating polym er parts are addressed. (C) 2000 Elsevier Science Ltd. All rights reserved.