Natural Electrorheological Fluids Based on Cellulose Particles in Olive Oil: The Filler Size Effect

The rheological behavior of 1 wt % suspensions of micro- and nanocellulose in olive oil is studied at various electric field strengths up to 7 kV/mm. The particle morphology is evaluated by optical and electron microscopy. Under an electric field, a contrast transition from a simply viscous behavior of fluids to a visco-elastic one is observed, while the suspensions show yield stress and storage modulus. A higher electrorheological response of suspensions filled with nanocellulose compared to microcellulose has been established. Based on the dependences of the static yield stress on the electric field strength, an analysis of the mechanism of the electrorheological effect has been provided. The use of completely natural components has shown promise of developing novel, environmentally friendly “smart” materials.