Three different models were used for the description of viscoelastic, yielding, and hardening stages of the mechanical behavior of a network polymer. As a representative response we get unidirectional loading test at a wide range of strain rates with the appearance of a distinct yielding point, strain softening, and strain hardening. The present analysis shows that Rubin's kinematics formulation appears to have some benefits in contrast to the other two approximations. (C) 2005 Wiley Periodicals, Inc.