Rheology of Karanja (Pongamia) Oil Based Biolubricant

Abstract

Rheology is the science of flow and deformation of liquids and semi-solid materials under the effect of an applied force. Rheological characterization of lubricating oils is important to predict their flow behaviour in each stage starting from preparation to processing up to application. Vegetable oils with high oleic acid content are considered the best candidate to substitute conventional mineral oil based lubricating oils and synthetic esters. The present article discusses the synthesis of biolubricant from non-edible Karanja oil in a two-stage transesterification process followed by reaction with branched neopentyl polyol to form polyol esters as the desired biolube product. The viscosity of synthesized biolubricant is measured at increasing temperatures using Rheometer model MCR302 by Anton Paar, Austria. The same apparatus was used for measuring shear stress, speed and torque. The study undertaken here intends to reveal relationship between viscosity and temperature, shear stress and shear rate; viscosity and shear rate and torque with shear rate of Karanja oil biolubricant. Variations in coefficient of viscosity with temperature, shear stress (τ) and shear rate (ϒ) are plotted accordingly. The synthesized biolubricant depicts Newtonian behaviour in hydrostatic regime.