Rheologica Acta, Vol.40, No.6, 570-581, 2001
A thermodynamic approach to the rheology of highly interactive filler-polymer mixtures: Part I - Theory
The rheological behavior of highly interactive filler-polymer mixtures is simulated utilizing a double network created by the entangled polymer matrix and the adsorbed polymer. Both networks are represented by a nonlinear viscoelastic constitutive equation. The dependence of rheological properties on filler concentration is taken into account through the bridging density resulting from polymer-filler interactions and a hydrodynamic reinforcement. The relative contribution of both networks is computed through the energy balance consistent with the thermodynamics of the polymer-filler chemical interactions and fluid mechanics. This self-consistent approach allows one to calculate the strain dependence of dynamic properties under oscillatory flow and shear rate dependence of stresses under steady simple shear flow and upon start up and cessation of shear flow.
Keywords:filled polymer;rheological model;Giesekus model;adsorption;thermodynamics;oscillatory flow;steady flow;transient flow;Payne effect;filler/matrix interaction