Small deformation response in gum and highly-filled elastomers

Small deformation viscoelastic response has been investigated in a series of five elastomeric binders, both with and without nonreinforcing filler. The filled systems were found to be both nonlinear viscoelastic and thermorheologically complex. These behaviors suggest the existence of a secondary relaxation process. The origin of this secondary process was modeled as an interphase of polymer weakly adsorbed on the filler surface. Decomposition of time-temperature shift factors for filled versus unfilled properties showed that the mechanical response of this interphase followed Arrhenius bahaviour. Measured activation energies ranged from 24 to 76 kJ/mole depending on the cohesive-energy density of the elastomeric binder.