The influence of cyclic loading conditions on the viscoelastic properties of filled rubber

This study deals with the effect of cyclic loading on the viscoelastic properties of filled nitrile rubbers. Classic strain amplitude sweeps were first carried out at two different temperatures (ambient and 80 °C) on both filled and unfilled nitrile rubber specimens in order to observe the influence of the fillers, temperature and loading conditions on the Payne effect. Some specimens were then subjected to a high number of cycles to study the variations in the viscoelastic properties and the sensitivity of the Payne effect to cyclic loading tests at several given strain amplitudes. It appears that the viscoelastic properties of rubber significantly evolve during the cyclic tests, which raises the question of the concept of cyclic stabilized behaviour.

► The viscoelastic properties clearly evolve during the cyclic loading tests.
► After the stress softening step, E′E′ is greater than its initial value, apart from the highest DSA.
► At 80 °C, E′E′ slowly increases after a short softening phase, due to vulcanization.