quote:
Originally posted by labman:
Oleic acid isn't as bad as the poly unsaturated ones, but it is still is unsaturated and will polymerize when exposed to heat and air without significant amounts of additives. Glycerin is one of the least stable polyols, having tertiary hydrogens. Trimethylol propane or pentaethrythol are more stable. Esters may make good lubes, but unless I can have ones made with a more stable base, I will stick to dino.
http://www.abiluni.org/HTMLpages/News/99_News_SNL.shtml
"Laboratory tests showed it to have excellent lubrication and wear-protection properties, but soybean oil's lack of oxidative stability and a tendency toward polymerization were concerns. Genetic modifications to the soybean itself were used to change the fatty acid content of the oil seed, raising its oleic acid content and increasing the soybean oil's oxidative stability. Partial hydrogenation and various additives also improved the vegetable-oil lubricant's laboratory performance, and it was judged ready for field-testing. "
http://www.hort.purdue.edu/newcrop/proceedings1999/v4-247.html
"The internal combustion engine is an extreme environment for vegetable oil. The combination of extreme pressure and heat frequently cause a polymerization of the oil, changing the oil into a plastic within a short period of time. This polymerization has been observed since the development of the internal combustion engine. Prior attempts after the turn of the 20th century found the lifespan of vegetable oils to be unacceptable for modern engine applications. As engine compression increased with increasing requirements of power and performance, vegetable oils were found to be severely lacking in performance. Vegetable oils frequently would polymerize within hours of engine startup. Attempts to use fatty acid esters derived from vegetable oils were successful but production costs made them unacceptable to consumers."
"The blending of any of several common base oils with hydroxy oils and wax esters, however, provided the initial functional motor oil. Modifications and variations of these oils have been made to adjust for various applications ranging from small, air cooled engine applications to water cooled, gasoline and diesel engines. Using a base oil derived from essentially any vegetable oil, initially being canola, with a relatively high concentration of monounsaturated fatty acids, was key to providing for an oil that met the objectives of the project."
KeepMedia > The Corn and Soybean Digest > February 15, 2004 >
"When research began on soy-based lubricants, one of the initial challenges was improving the oxidative stability of soy-based oils. "
"'Vegetable-based oils tend to oxidize and, if not controlled, form a gel on the top layer of the oil, which can hinder performance,' says Diane Neuzil of the Agriculture-Based Industrial Lubricants (ABIL) Research Program."
"She reports that the oil was chemically modified and chemical additives were used to solve the
stability issue."
"But through research such as the Better Bean Initiative, high-oleic soybeans have now been
developed that produce more stable oil from the seed."
"As a result, little modification is needed to meet the needs of lubricant manufacturers."
http://www.sterlinggrade.com/index.htm
I think you'll find that the polymerization problem has been licked by a combination of
relatively low cost techniques, including genetic modifications to the seeds.