الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The development of lubricants is traditionally based on mineral oil which is a fossil raw material. Therefore, lubricants produced from mineral oil have well-established, good technical performance and are lower cost compared with others, so commonly used. They consist mainly of hydrocarbons but also contain some sulfur and nitrogen compounds with very small amounts of a number of metals.
Due to the increasing of environmental issues like waste disposal problems, non-biodegradable resources, green house effect, etc. and also the reduction of petroleum oil resources, renewable oils from vegetable origin have become an important issue since many evidences prove that the substitution of renewable resources for mineral oil feedstocks can be a sustainable development. Now a days, the lubricants from renewable harvestable resources are a successful reality in many parts in the world.
In general, vegetable oils have many advantages such as high flash point, high viscosity index, high lubricity and low evaporative loss besides eco-compatible, renewability and non-toxicity. But there are still some limitations that industries have not been able to overcome, such as low resistance to oxidative degradation at high temperature and poor low temperature properties. The reasons for the instability of vegetable oils are the structural unsaturation in the fatty acid part and the “β-CH group” of the alcoholic components.
A lot of technical solutions such as chemical modification and additivation have been suggested to overcome these limitations. For the chemical modification on the industrial level, reactions on the unsaturation are in the second place (less than 10 %) after the reactions on carboxylic/ester groups (more than 90%). However, industrial and academic research in oleochemistry concentrate more on the former, on the hydrocarbon chain of fatty acids, especially on the carbon-carbon double bonds of the unsaturated fatty acids and the major reactions on the unsaturation applied in industry are hydrogenation and epoxidation.
This investigation deals with the preparation of environmentally friendly bio-lubricants. To achieve this goal, the following points were studied:
1. Seven different alkyl oleates were prepared via reaction of oleic acid with different alcohols, (decanol, oleyl alcohol, isoamyl alcohol, 2-ethyl-1-hexanol, neopentyl glycol, trimethylolpropane and pentaerythritol). Then seven different epoxidized products were obtained by reaction of the prepared alkyl oleates with mixed catalyst. Subsequently hydroxylation of the epoxidized products using 2-ethyl-1-hexanol to give seven different products. Thereafter acetylation of the latter products using acetic anhydride.
2. Chemical modification of vegetable oils (Soybean oil, Castor oil and Jojoba oil) using the following procedures: epoxidation of these oils by mixed catalyst followed by transesterification of soybean oil and castor oil. Subsequently hydroxylation of the products using 2-ethyl-1-hexanol to give three different products. Finally acetylation of the latter products using acetic anhydride.
The prepared compounds were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), and Proton Nuclear Magnetic Resonance (1H-NMR). Determining of the molecular weights using Gel Permeation chromatography (GPC) was also performed.
The prepared compounds were evaluated as bio-lubricants. It was found that the viscosity index increases with increasing the alkyl chain length, and decreases with increasing branching. Product (B3) has the highest value of (VI) than the other prepared compounds and the product of (CAS4) showed the highest (VI) compared with the other modified oils.
Moreover, pour point decreased with increasing degree of branching to prevent wax crystal aggregation. All the prepared products have cold flow properties better than commercial lubricants. Product (G3) has the lowest value of (PP) than the other prepared compounds and the product of (CAS4) has the lowest (PP) compared with the other modified oils.
All the prepared products have suitable flash points and measuring (TAN) indicated that all the reactions took placed completely. Thermogravimetric analysis showed that the prepared products attained thermal stability which allows their use within the temperature limits illustrated in the thermo diagram.
Furthermore, rheological studies revealed that all the prepared products achieved a Newtonian behavior with constant dynamic viscosity against shear rate. Finally, tribological studies showed that all the prepared products have good lubricity and frictional properties compared with commercial lubricants.