Resumen
Canola oil cannot be directly used as a fuel in diesel engines because its physicochemical properties differ considerably from those of diesel oil. Therefore, the studies were intended to make closer the surface tension, viscosity and density of the canola oil to those of diesel fuel by adding n-hexane and ethanol. The surface tension and its components as well as density and viscosity were determined not only for the canola oil mixtures with n-hexane and ethanol but also for the canola oil components. The surface tension components were determined based on the contact angle measurements on PTFE. To obtain the components and parameters of saturated fatty acids, the contact angles of water, diiodomethane and formamide on their layers were measured. The contact angles of the studied mixtures were also measured on the engine valve. The obtained results and theoretical considerations allowed us to explain why the values of the surface tension, density and viscosity of canola oil are higher than those for its components. They also contributed to the explanation of the mechanism of the reduction in these quantities for canola oil by the addition of n-hexane and ethanol. It appeared, for example, that viscosity of the canola oil mixture with 20% n-hexane contacted with ethanol is close to that of diesel fuel.