Lignin is usually considered as byproduct or even waste in pulp and paper industry, and is mainly used as the low value material for energy recovery. Our previous studies indicate that lignin can be served as high performance lubricant additive, which provide a new high value-added application for lignin. However, the poor solubility and the diversity of lignin structures and chemical compositions limit the utilization of lignin in lubricants. The objective of this project is to understand the solubility and the tribological behavior of lignin in different base fluids with the involvement of a new type of molecular interaction called reciprocal hydrogen bonding (rcp-HB) and to provide a sustainable solution to existing petro-lubricants/additives. The hypotheses of the research are: 1) introducing rcp-HB between lignin and base fluids could enhance their interactive bonding and therefore lignin dissolution; 2) rcp-HB promotes the adhesion of lignin contained lubricants to friction surface, toughens lubrication film and improves boundary lubrication. The effect of the molecular structure of base fluids and the surface modification of lignin on the solubility of lignin and the lubricants performance will be systematically investigated. Lignin from different resources and different extraction processes will also be studied to figure out the effect of lignin structures and chemical compositions on lignin solubility and lubricating performance.
Division of Machine Elements, LTU (Assoc. Prof. Yijun Shi)