Two different thermal treatments were applied to polycarbonate (PC) in terms of slow cooling (annealed samples) after a thermal treatment at a temperature above the glass-transition temperature or abrupt cooling in a liquid-nitrogen environment (quenched samples). Tensile and compression experiments were performed on the two types of samples at three different effective strain rates. A viscoplastic model based on the fundamental assumptions of the Eyring model and on a kinematic formulation, which separated the viscoelastic and plastic strain, developed in previous works, was used to describe the yield and post-yield behavior of thermally treated PC. The different thermal treatments affected the parameters of the material microstructure. A satisfactory agreement between the experimental data and calculated results was found. (c) 2005 Wiley Periodicals, Inc.