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, shear thinning becomes more pronounced when shearing from low to high rates than in the opposite direction. We attribute this to a greater degree of filler orientation during up-shear. 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 behaviour is controlled by frictional and adhesive contacts, with the model suggesting that the adhesive stress is temperature dependent.
|Status||Udgivet - 6 jul. 2022|