Proprietes viscoelastiques des reseaux a l'etat caoutchoutique

The dynamic properties and the stress relaxation of vulcanisates of natural rubber, cis-polybutadiene and a butadiene (76,5)-styrene (23,5) copolymer are analysed in order to determine the influence of some structural parameters on the shape and position on the time scales of the rheological functions characterizing their viscoelasticity.The persistence of the energy loss at low frequencies and the corresponding high level of the distribution of relaxation times are all the more marked as these polymer networks are less cross-linked or contain a larger amount of carbon black HAF. Undoubtedly closely related to the “viscoelastic plateau” of linear polymers, this anomaly is interpreted in terms of an extension of the Rouse theory derived for bulk polymers or their concentrated solutions.