Electrorheology as a Support Tool for Understanding the Electrotribological Behavior of Nanocellulose-Based Biolubricants

This research aims to explore the behavior of sustainable electrorheological lubricant fluids. Rheological data allows for the analysis of the strength of a chain-like structuration stimulated by an electric field, as well as the angular orientation of nanocellulose particles’ suspensions. Commercial fibrillated (CNF) and crystalline (CNC) nanocelluloses were dispersed in castor oil at concentrations of 1 and 4 wt.%. Oscillatory flow tests were performed within the linear viscoelastic range, following a pre-shear step, and under the effect of an electric field. The consequent structuration of nanocellulose particles were visualized using a microscope attached to the rheometer. Squeeze flow test and tribological analysis were also performed. Storage and loss moduli were found to increase with increasing values of the electric field, and high pre-shear caused structures to break and form new chains, reducing storage and loss moduli at low values of the electric field. Regarding the squeeze flow tests, dispersions were found to exert an opposite force to compression which grew up with increasing values of electric field and concentration. Finally, friction coefficient values were found to be electro-responsive while wear was found to decrease when applying an electric potential.