Unique plastic and recovery behavior of nanofilled elastomers and thermoplastic elastomers (Payne and Mullins effects)

We have proposed recently that the mechanical properties of nano-filled elastomers are governed by the kinetics of rupture and re-birth of glassy bridges which link neighboring nanoparticles and allow for building large rigid clusters of finite life-times. The latter depend on parameters such as the temperature, the nanoparticle-matrix interaction, and the distance between neighboring fillers. Most importantly these life-times depend on the history of deformation of the samples. We show that this death and re-birth process allows for predicting unusual non-linear and plastic behavior for these systems. We study in particular the behavior after large deformation amplitude cycles. At some point we put the systems at rest under large deformation, and let the stress relax in this new deformed state. During this relaxation process the life-time of glassy bridges increases progressively, even for large deformation states. The systems thus acquire a new reference state, which corresponds to a plastic deformation. The stretching energy of the polymer strands of the rubbery matrix is larger than in the initial undeformed state, but this effect is compensated by a new configuration of glassy bridges, which are much stiffer. For plastic deformations of less than about 10%, the new system acquires mechanical properties around this new reference state which are very close to those of the initial system. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1495–1508, 2010