The behavior of thermoplastics depends on several factors, mainly time and temperature. The present work is the subject of a study of the dependence of these materials on time. The material considered in this study is a polyamide 6. The applied behavior model is represented by the Kelvin-Voigt viscoelastic mechanism with instant elasticity. Following the mathematical formulation of the equations of the model, tensile tests at different strain rates are conducted. The model parameters are then identified. These being sensitive to the strain-rate, the relation which links them with it is established by means of an exponential regression. The experimental results and those obtained by the model are presented, compared and interpreted. Their relevance and coherence validates both the model and the approach adopted.