Dispersion stability and rheology study of canola oil containing TiO2 nanoadditives for tribological applications: An experimental approach

Recently, the biodegradable lubricants developed from vegetable oils are gaining popularity concerning biodegradability and sustainability. Moreover, the stabilized suspension of nanoparticles in the base lubricant is a crucial requirement of any nanolubricant for the long term. To evaluate the aggregation behaviour of nanoparticles in base lubricant and rheological properties of nanolubricants are important as other properties. Keeping in view of these, the aim of the present study has been categorized into two parts. Firstly, the dispersion stability of nanofluids in terms of the aggregation behaviour of nanoadditives with the standing time has been investigated under three non-ionic surfactants and one anionic surfactant with several TiO2- to-surfactant mass ratios utilizing dynamic light scattering (DLS) technique. The outcomes demonstrated that the TiO2- to-Triton X-100 mass ratio of 1:3 has long term stability. Secondly, the rheological behaviour of canola oil containing a varying range of nanoadditives has been conducted for various temperatures and shear rates. The results indicated that all the nanofluids exhibit Newtonian behaviour and the viscosity of canola oil increases as nanoadditives concentration increases. The experimental results are also compared and validated with the existing viscosity models, and a new regression model has been suggested.