Synthesis and physicochemical properties of novel lauric acid capped estolide esters and amides made from oleic acid and their evaluations for biolubricant basestock

Autor: Mohd Zan Arniza, Shoot Kian Yeong, Nek Mat Din Nik Siti Mariam, Seng Soi Hoong, Abu Hassan Noor Armylisas
Rok vydání: 2019
Předmět:
Zdroj: Industrial Crops and Products. 140:111653
ISSN: 0926-6690
DOI: 10.1016/j.indcrop.2019.111653
Popis: Vegetable oils have been used as environmentally friendly biolubricants because of their inherent biodegradability, good lubricity, higher viscosity index and low evaporative loss. However, their use is limited due to significantly poor cold flow properties and inferior oxidative stability. This paper presents an approach to modify vegetable oil derivatives namely oleic acid to yield biolubricant with good cold flow properties and oxidation stability. Oleic acid was converted to polyhydroxy estolide through reaction with only hydrogen peroxide, which is considered a ‘green’ oxidant. The synthesized polyhydroxy estolide was further reacted with appropriate amount of lauric acid to end-cap its hydroxy groups, which yielded lauric acid capped estolide as the product. Subsequently, the prepared lauric acid capped estolide was reacted with branched and straight chain alcohols as well as secondary amines to afford estolide esters and amides. In general, most of the prepared samples showed improved cold flow properties as compared to vegetable oil-based lubricants, where the best pour point (−41 °C) was achieved by 4-methyl-2-pentyl estolide ester. Meanwhile, estolide amides exhibited the best oxidative stability among samples evaluated with an oxidation onset temperature of 205 °C, which is significantly higher than vegetable oil-based lubricants. Generally, the oxidative stability, viscosity index and anti-wear properties of prepared estolide esters and amides were found to be comparable to the properties of commercial samples used as benchmark.
Databáze: OpenAIRE
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