Valorization of bark to natural lubrication additives via fractionation based on chemical product engineering concept

In this work, the natural lubricating components from Cork bark (CB) and Populus bark (PB) were obtained by catalytic reduction fractionation and liquid–liquid extraction. GC–MS, 2D-NMR, and GPC some techniques were used to characterize the chemical composition of the CB and PB extract. The main components of CB and PB are suberin-derived aliphatic and alkaloid, respectively. CB and PB extract have been demonstrated as efficient organic lubricating additives to reduce wear rate and stabilize friction coefficient of paraffin lubricant. Interestingly, the addition of CB or PB extract in paraffin shows better lubrication performance as compared with commercial lubricants. In addition, XPS results show that some compounds such as suberin-derived aliphatic and alkaloid from bark could enhance lubricating oil film to reduce friction and wear. Overall, this work will replace the conventional petroleum based lubricating additives and open a new application venue for bark to improve product value.