Rheology of polydisperse nonspherical graphite particles suspended in mineral oil
Th. Larsen, A. L. Søbye, J Royer, Wilson C. K. Poon, Thomas Larsen, Søren Juhl Andreasen, Aleksey D. Drozdov, Jesper de Claville Christiansen
Abstract
We study the role of filler concentration and microphysics on the rheology of polydisperse flake-graphite particles suspended in Newtonian mineral oil. Under steady shear, our samples exhibit shear thinning, and yielding behavior is observed for volume fractions ϕ>0.18. Time-temperature superposition was observed using an Arrhenius-type horizontal shift factor, giving a flow activation energy that is dependent on the graphite volume fraction, suggesting concentration-dependent contributions to relaxation processes in the suspensions. The flow curves are fitted by a constraint-based model, indicating that the flow behavior is controlled by frictional and adhesive contacts, with the model suggesting that the adhesive stress is temperature dependent.