VISCOELASTIC PLASTIC RHEOLOGICAL MODEL FOR PARTICLE FILLED POLYMER MELTS

A viscoelastic plastic model for suspension of small particles in poly mer melts has been developed. In this model, the total stress is assum ed to be the sum of stress in the polymer matrix and the filler networ k. A nonlinear viscoelastic model along with a yield criterion were us ed to represent the stresses in the polymer matrix and the filler netw ork, respectively. The yield function is defined in terms of different ial equations with an internal parameter. The internal parameter model s the evolution of structure changes during floc rupture and restorati on. The theoretical results were obtained for steady and oscillatory s hear flow and compared with experimental data for particle filled ther moplastic melt. The experimental data included the steady state shear stress over a wide range of shear rates, the transient stress in a sta rt up shear flow, stress relaxation after cessation of a steady state shear flow, the step shear and the oscillatory shear flow at various a mplitudes.