Synthesis of Rosin-Derived Surfactants and Their Potential Application in Metalworking Fluids

Despite the widespread use of metralworking fluids to increase productivity and quality of manufacture operations during metal forming processes, they pose significant environmental and performance challenges such as improving the lifetime of the fluids while utilizing more environmentally friendly materials. Metalworking fluids are often destabilized by accumulations of hardness ions and bacterial growth. In order to address these issues, the synthesis of rosin-bases surfactants and their potential use in metalworking fluids is the main focus of this work. Rosin is a natural material with interesting antimicrobial properties. It is obtained from pine trees and consists of a mixture of tricyclic carboxylic acid isomers, mainly abietic, pimaric, levopimaric and dehydroabietic acids (C19H29COOH). The synthesis of the surfactants was performed by reacting rosin with triethanolamine and sodium hidroxide which were further tested for stability in hard water, tolerance towards bacterial growth and tribological performance. The hard-water stability was measured using a turbidimetric method. The bacterial growth resistance was performed using burkholderia cepacias as a model contaminant. The tribological performance was evaluated using a ball-on-disc tribometer in a steel-aluminum contact and the specimens were characterized by SEM/EDS, micro-FTIR and micro-Raman.