At this point, we already know that as a base oil for lubricants, the higher the content of linolenic acid in vegetable oil, the worse its oxidation stability. However, linolenic acid is a polyunsaturated fatty acid with three double bonds, which is an essential omega-3 fatty acid for the human body. As the human body cannot synthesize it itself, it needs to be ingested from the outside. In the human body, it can be converted into EPA and DHA, which have great benefits for cardiovascular and cerebrovascular health. It is rich in flaxseed oil and deep-sea fish oil. DHA, also known as docosahexaenoic acid or brain gold, is a very important unsaturated fatty acid for the human body and an important member of the omega-3 unsaturated fatty acid family. EPA， The abbreviation for eicosapentaenoic acid is the main component of fish oil. Due to the presence of three double bonds in alpha linolenic acid molecules, it has strong reducibility and can be oxidized by high temperatures, oxygen in the air, ultraviolet radiation, and some heavy metal ions. Therefore, edible oils rich in alpha linolenic acid should be stored away from light and sealed. When using, high-temperature frying should be avoided as much as possible, and an appropriate amount of vitamin E should be added to the oil for protection.

In foreign countries, modern biotechnology has been used to cultivate plants with high oleic acid content, such as Cano1a oil and high oleic sunflower seed oil (HOS0), whose oleic acid content can reach over 90%, thereby improving antioxidant properties, but at a higher cost than general plant oils. The so-called modern biotechnology here refers to genetic modification - transgenic technology - to increase oleic acid content. So, hearing about genetic modification and turning pale is, in some ways, an undesirable non scientific attitude.

Another method is to combine synthetic esters with vegetable oil. First, the fatty acids separated by hydrolysis of the vegetable oil are purified to remove linoleic acid and linolenic acid, but the fatty acids are not distilled and separated. The mixed fatty acids are then esterified with trimethylolpropane to obtain a product with good low-temperature performance and oxidation stability. In recent years, there have also been 'environmentally friendly lubricating oil products based on vegetable oil' in China. In fact, this is a development direction, but the above expression method is somewhat suspected of changing concepts. Why cover up the direction of technological progress that benefits humanity? If we delve into its rationale, it should also be 'synthetic ester products made from vegetable oil as lubricating base oil'.

Epoxidation is also a method to improve the oxidative stability of vegetable oils, which involves the oxidation of double bonds in unsaturated fatty acids into epoxy rings. For example, the oxidized soybean oil and oxidized soybean oleic acid octyl ester that can be seen in the market are examples, which can be used as oiling agents and multi effect anti-wear agents. Regarding vegetable oil, we can summarize as follows:

advantage:

ⓘ Oily - Strong lubricity, low friction coefficient; ② High oil film bearing capacity and strong anti-wear performance; ③ High viscosity index and good viscosity temperature characteristics; ④ Good biodegradability and minimal environmental pollution; ⑤ Non toxic, non irritating, and extremely low ecological toxicity.

Disadvantages:

① Poor oxidation stability and thermal stability; ② Poor water resistance and hydrolysis stability; ③ Poor solubility for certain additives.

Performance comparison between vegetable oil and mineral oil under the same experimental conditions