SiO2 Reinforced EVM/TPU Blends: Bound Rubber and Rheology Behavior

Silica is shown to be a more active filler than carbon black for the reinforcement of EVM/TPU blends. The static rheology of EVM/TPU blends is considerably influenced by a tightly bound rubber structure developing between the TPU and silica that was identified by a tetrahydrofuran extraction test and SEM observations. Dynamic rheology behavior corroborated the development of bound rubber and indicated the existence of the Payne effect because of filler-filler networks in the blends. The silica-TPU interaction is thermally unstable at 190°C and mechanically unstable at a shear frequency of 1 Hz.