Although biobased and biodegradable lubricants have been around since 1980s, there is still a need to clarify the difference between natural vegetable oils, chemically modified vegetable oils, esters made from vegetable oils and the resulting biodegradable products. There are also new terminologies beyond biodegradability that refer to environmentally friendly lubricants. Terms such as Biobased, Bio-Preferred, Environmentally Aware Lubricants (EAL); and Vessel General Permit (VGP) are relatively new and also need to be explained.

Vegetable Oils Vegetable oils refer to oils that are extracted from plants, seeds, kernels, nuts, or grains. Based on their economic impact in their respective regions they are divided into Major Oils, Minor Oils, and Non-Edible Oils1


No.127 page 1

Biobased-Biodegradable, Vegetable Oils, Biobased Esters: How to choose?

Dr. Lou A. Honary, Environmental Lubricants Manufacturing, Inc.

. Major oils include oils like soybean, palm, rapeseed (canola), sunflower, cottonseed. Coconut, peanut, olive, palm kernel, corn, linseed, and sesame. Minor oils are known for their uses but do not match the larger production levels of Major Oils. They include oils like niger, mango kernel, poppy, cocoa bean, shea, grape seed, and the like. Non-Edible Oils include castor, tung, and tall that are commercially grown for their chemical properties.

Vegetable oils are made of triglycerides. A triglyceride or triacyl glyceride is a lipid molecule or a fatty ester derived from glycerol and three (tri) fatty acids. When considering materials for grease manufacture,


not all vegetable oils are the same. Their fatty acid profiles vary considerably; and fatty acid profiles are indicators of stability of the oil when considering use. Because oxidation stability is fundamentally important in the longevity of industrial lubricants, it is important to review their fatty acid profiles and the percentage of some key fatty acid contents. Of the fatty acid constituents of vegetable oils those with more stability are desirable, but they negatively impact cold temperature flowability. For example, stearic acid is a fatty acid with no double bonds which makes it oxidatively stable, but it is solid at room temperature and cannot flow. Oleic acid on the other hand has one double bond that makes it less stable than stearic acid, but it is liquid at room temperature and can provide flowability for use in industrial lubricants, but it still impacts the pour point of the oil negatively. Similarly, Linoleic acid with two double bonds, and much worse Linolenic acid content with three double bonds, provide better fluidity at cold temperatures but impact oxidation stability negatively and exponentially.

Some seed oils have been modified through genetic selection, breeding, or genetic and transgenic modifications. For example, canola oil is a genetic variation of rapeseed with low or zero percent erucic acid content. High oleic soybeans produce oils with high oleic acid content with better oxidation stability. But varieties that have higher percentage of linolenic acid could show a relatively poor oxidation stability even if they have high oleic acid content.

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