Synthesis of Estolide Ester and Amide from Acetylated Polyhydroxy Estolide for Lubricant Base Oil

• Published in: European journal of lipid science and technology Vol. 122; no. 10
• Main Authors: Hoong, Seng Soi, Arniza, Mohd Zan, Mariam, Nek Mat Din Nik Siti, Armylisas, Abu Hassan Noor, Ishak, Siti Afida, Ismail, Tuan Noor Maznee Tuan, Yeong, Shoot Kian
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-10-2020
• Subjects: Acetic acid; Acids; antiwear; Biodegradability; biodegradable; Biodegradation; estolide; Hydrogen peroxide; Lauric acid; lubricant; Lubricants; Lubricants & lubrication; Oil; Oleic acid; Oxidation; Physicochemical properties; Properties (attributes); Stability
• ISSN: 1438-7697; 1438-9312
• DOI: 10.1002/ejlt.202000098

Plant oil‐based lubricants are used as alternative for mainstream petroleum‐based lubricants mainly because they are known to be environmentally friendly. However, their market acceptance is limited by their high pour point and poor oxidation stability. This study presents an approach to make biodegradable lubricant from oleic acid that shows low pour point and satisfactory oxidation stability. A mixture of estolides with acetyl and hydroxy functionalities is prepared from reaction between oleic acid, acetic acid, and hydrogen peroxide. Subsequently, the hydroxy groups of estolide are end‐capped with lauric acid to improve oxidation stability. Further reaction with alcohol and amine yielded estolide ester and amide, respectively. Physicochemical properties evaluation of prepared estolide ester and amide reveal that they have properties comparable to commercial samples in terms of pour point, oxidation stability, viscosity index, and antiwear. Furthermore, both estolide ester and amide are found to be readily biodegradable, which support their use as environmental friendly lubricant. Therefore, the inferior properties of plant oil‐based lubricants can be resolved by chemical modifications that yield specific estolide ester and amide with excellent properties suitable for lubricants.
Practical Applications: The prepared estolide ester and amide have good potential to be used as lubricant base oil for environmentally acceptable lubricants due to their inherent readily biodegradability nature and excellent lubricant properties.
Oleic acid can be chemically modified to yield a mixture of estolides with acetyl and hydroxy functionalities. Subsequent chemical modifications generated estolide ester and amide that exhibit physicochemical properties comparable to commercial lubricant samples. Furthermore, both estolide ester and amide are found to be readily biodegradable, which support their use as environmentally friendly lubricant.