Vegetable oils can offer important environmental advantages with respect to biodegradability and renewability, as well as good performances in different applications. In this work, the rheological and tribological properties of an industrial canola oil-based bio-lubricant were investigated. They were compared with the properties of a mineral hydraulic lubricant used for similar applications. The tribological performance of the lubricants was investigated using a four-ball test and a pin-on-disk setup, and the rheological behavior was studied using oscillatory rheometry. The tested bio-hydraulic oil exhibited excellent lubricity. Liquid crystal additives affected the viscoelasticity differently. Moreover, the added ionic liquid crystal improved the wear resistance of the bio-hydraulic oil, but the original lubricant preserved the lowest coefficient of friction.

The use of vegetable oils can offer important environmental advantages with respect to biodegradability and renewability, along with good performance in a range of different applications. Unlike petroleum-based lubricants, which have been studied and developed over a century, knowledge related to vegetable-oil-based lubricants is limited. In this work, the rheological properties of industrial canola-oil-based bio-lubricants were investigated using a rotary rheometer. The bio-hydraulic oil exhibited constant viscosity at both moderate and high shear rates, as well as shear thinning at low shear rates and temperatures less than 30 ℃. Frequency sweep tests revealed significant viscoelasticity in the bio-hydraulic oil, which developed over time. Time dependence and structure recovery effects were also investigated. These experiments reveal some characteristic liquid crystal fingerprints. To the best of our knowledge, this study is the most extended rheological characterization of low-viscosity vegetable-oil-based lubricants.

The rheological behavior of a canola oil-based bio-lubricant was correlated with its surface activities using a rotary rheometer. The experiments on the gap size, substrate, and surface conditions led to a consistent and conceivable assumption that the self-assembled monolayer was extended to a degree that was sufficient to make a significant change in the bulk properties. In parallel, the thermal behavior was also connected to the surface activities. Differential scanning calorimetry was used to measure what is thought to be the monolayer melting point without using a graphite substrate. Crystallization points were measured at relatively high temperatures. Tribological tests were conducted and explained based on the rheological and thermal findings. A scenario describing both the boundary and bulk regimes was hypothesized. Rheometry and thermal analysis techniques are promising because of the variety of variables that could be controlled, such as temperature, shear, time, gap and substrate. To the best of our knowledge, this is the first study using macroscopic rheology to study the surfactant activities of vegetable oil. The influence of substrate and gap size on rheological behavior could change the current standards for using rotary rheometers.