Isopropyl-branched Lard and its potential application as a bio-based lubricant

Authors: Yosief, Hailemichael; Sarker, Majher; Bantchev, Grigor; Dunn, Robert

Submitted to: Lubrication Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2023
Publication Date: 9/21/2023
Citation: Yosief, H.O., Sarker, M.I., Bantchev, G.B., Dunn, R.O. 2023. Isopropyl-branched Lard and its potential application as a bio-based lubricant. Lubrication Science. https://doi.org/10.1002/ls.1673.
DOI: https://doi.org/10.1002/ls.1673

Interpretive Summary: Most lubricating fluids are produced from petroleum. Interest is growing developing lubricants from renewable resources to replace fossil-based materials. In this study a low-valued inedible lard collected from a local rendering house was structurally modified through chemical synthesis to use it as a bio-based lubricant. The application-based properties of modified lard were determined using a combination of different analytical techniques. The modified lard showed better oxidation stability, improved properties to be used in cold condition, and higher density and kinetic viscosity than unmodified lard meaning it has better potential to be used as a lubricant in a variety of applications. From this study, it is proven that inedible animal fat like lard can be used as an alternative renewable feed stock for making value-added product such as ingredients for bio-lubricant. This information will be useful to those industries with excess animal fat wastes or those interested in producing biobased lubricants.

Technical Abstract: Regular lard (RL) was chemically modified into isopropyl-branched lard (BL). The isopropyl group was introduced in the triglyceride structure through the reaction of carbon-carbon double and isopropyl bromide in presence of ethylaluminum sesquichloride. The reaction was confirmed with GC-MS, NMR (1H, 13C, 2-D), IR spectroscopy, etc. The physical, chemical and tribological properties of the RL and BL as well as their blends in polyalphaolefin (PAO-6) and high oleic sunflower oil (HOSuO) were investigated. At room temperature, the BL displayed better solubility in both HOSuO and PAO-6 than RL. Compared to RL, BL also displayed higher density, higher viscosity, higher oxidation stability and better (lower) cold flow properties (pour point and cloud point) both as a neat material and blends in HOSuO or PAO-6. However, BL displayed lower viscosity index (197 vs 162) compared to RL. Both RL and BL displayed similar lubricity as HOSuO and showed potential as a good lubricity additive in PAO-6 even in small amounts (~10 wt. %) as demonstrated by low friction coefficient and wear scar diameter values. This study demonstrates that introducing alkyl branching into lard can lead to improved physico-chemical properties and lubrication performance.