2012 Volume 8 Pages 9-14
Change and restoration in carbon black filler network in SBR through reversing double-step large shear deformations were studied by the use of differential dynamic modulus. Unfilled rubber showed drop and complete recovery in G′ after elimination of step shear strain γ=0.5, showing drop in G′ is not due to chain scission but due to filler network rupture. Filled rubber also shows similar change and recovery in G′, but rises over the initial value at long time region. This long time behavior may be due to physical aging. Elimination of the effect of physical aging allowed us to estimate relaxation time in restoration process. It was concluded that (a) differential dynamic modulus measured in recovery process is useful for the characterization of filler network, (b) carbon black filler network ruptured by strain recovers to the original structure by particle diffusion process, and (c) recovery rate of carbon black filler network is independent of amount of filler loading and deformation history.
