Electric Field Responsive Smart Fluids from Olive Pulp Powder

This study aims to evaluate one of the wastes of the olive oil industry, olive pulp powder (OP), due to its consisting of mainly polarizable lignocellulosic biomass, as a dispersed phase in electric field-responsive (ER) fluid whose rheological properties can be tuned by an externally applied electric field (E). The supplied OP was extracted with n-hexane, and structural and thermal analysis revealed the removal of residual oil and soluble small molecules. The OP and n-hexane treated-OP (h-OP) were dispersed in silicon oil (SO), and their rheological and dielectric properties, and dispersion stabilities were investigated. According to the flow test results, the yield stresses (τy) of both dispersions increased with increasing concentration and the E. The τy of the OP/SO and h-OP/SO dispersions (25 wt%) under E=3.5 kV/mm increased 29 and 130 times greater than their τy values under no E, respectively. The dielectric spectrum analysis showed that enhanced interfacial polarization and decreased nonpolarized forces after the n-hexane extraction improved the ER response of the h-OP/SO dispersion. The enhanced dispersion stability (90%) was determined for h-OP/SO dispersion at 25 wt%. As a result, the h-OP could be a sustainable candidate for evaluation as a dispersing phase of ER fluids for vibration-damping systems.