Comparison of recovery behaviors of thermally aged SBR composite from compressed and circular deformations

Recovery behaviors of the SBR composite from the compressed and circular deformations after thermal aging were compared. Instantaneous recovery and target recovery time to describe the sealing properties of a sealant were obtained from the recovery variation with the measuring time. For the compressed deformation, the recovery decreased at the initial measurement time and then increased. Since the recovery from the compressed deformation showed a local minimum and the minimum point varied in accordance to the thermal aging conditions, the linearity of the recovery variation was very low. For the circular deformation, the recovery continuously increased as the measurement time elapsed, the linearity was very high, and the instantaneous recovery of less than 0.1 s could be obtained from the extrapolation method. The circular deformation method was found to be suitable for study of recovery behaviors of a rubber article. The recovery behaviors varied with the thermal aging conditions and the difference was explained with the crosslink density change by the thermal aging.