Probing the effect of thickener microstructure on rheological and tribological properties of grease

The thickener microstructure strongly determines the properties of lubricating grease. Here, four types of grease were synthesized through different thickeners (lithium complex soap, polyurea, calcium sulfonate complex soap, bentonite), thickening polyalphaolefin. The influence of the thickener microstructure on the physicochemical, rheological, and tribological properties was evaluated. Results show that the lithium complex soap with a spiral fiber structure shows the best physicochemical properties and the highest yield stress. The four greases show the shear-thinning behavior because of the deformation of the thickener structures. The calcium sulfonate complex soap with a dense porous structure presents optimal tribological properties because of the synergy effect of the thickener deposited film and the tribo-chemical reaction film.