Analysis of viscosity-temperature behaviour of karanja oil trimethylolpropane ester bio-lubricant base stock

Abstract

The work presented deals with the viscous flow characterization of karanja oil based bio-lubricant base stock. Karanja oil trimethylolpropane ester (KOTMPE) bio-lubricant base stock was prepared from karanja oil methyl ester (KOME) and trimethylolpropane (TMP) using acid-catalyzed transesterification synthesis protocol. The viscosities were measured at 10-60 °C and 10-1000 s–1 shear rates using model HR-3 Discovery Hybrid rheometer. The viscosity-temperature interdependences at different shear rates were modeled using the Arrhenius equation. The viscosity values predicted with Arrhenius model were found in good agreement with measured values. The flow behaviour index of KOTMPE bio-lubricant stretched from 1.036 to 1.527, which suggested a gradual shift in fluid behaviour from Newtonian to non-Newtonian with increase in temperature. The study confirmed that Arrhenius equation along with Ostwald-deWaele power law could be used to predict the apparent viscosity and flow behaviour of synthesized KOTMPE bio-lubricant oil.