par Decerf, Jacqueline
Référence Polymer communications Guildford, 32, 5, page (143-148)
Publication Publié, 1991
Article révisé par les pairs
Résumé : Mechanical damping measurements of small amplitude are superimposed on polycarbonate strained in the non-linear viscoelastic range. The experiments are carried out on specimens aged at room temperature for various lengths of time after quenching from above Tg. A simple rheological model is used to describe the stress and time dependence of the viscosity. It is derived that the increase of viscosity at the first stage of deformation may result from the non-linearity of the stress-strain relationship, without any change of the parameter linked to the structural state, whereas the influence of preliminary ageing that manifests itself by an increase of the viscosity under stress is consistent with free volume relaxation.