Synthetic lubricants pour point

One hquid in this class intended for aircraft engine use is described in military specification MIL-L-87100 for operation from +15 to 300°C. Limitations of this class of synthetics are pour points of +5°C and higher, relatively poor lubricity, and high cost of 265/L ( 1000 + /gal) (44). Polyphenyl ether greases are available with good radiation resistance for appHcations in the temperature range of +5 to 288°C. 

White, waxy nearly odorless solids used as defoamers and feedstock for emulsifiers, lubricants, pour point depressants, and synthetic waxes and binders. 

More recent developments in this country have included synthesis of relatively stable oils of low volatility, low pour point, and high viscosity index by esterification of octyl alcohols, such as 2-ethylhexanol, with dibasic acids such as adipic acid and sebacic acid (3). Octyl alcohols may be synthesized from petroleum hydrocarbons via the oxo process. Although of relatively high cost, these synthetic oils find general application in making greases for lubrication of antifriction bearings and instruments in aircraft. 

Lubricants are formulated products composed of a base stock, which is either a mineral or synthetic oil, and various specialty additives designed for specific performance needs. Additive levels in lubricants range from 1 to 25% depending on the application. Synthetic base stocks are oligomers of small molecules, synthesized to a defined molecular weight. Important performance indicators include viscosity index which measures the viscosity index behavior over a temperature range, oxidative stability, and pour point. The performance of synthetic and mineral oils (Morse, 1998 Shubkin, 1993) is summarized in Table 2.7. 

Most of the hydrogenation studies deal with hydroxytelechelic polybutadienes (HTPB). This reaction takes place on activated charcoal or Raney nickel at temperatures between 25 to 105 °C. After a few hours, about 50% of double bonds are hydrogenated. These products are interesting in the propellant field, but especially as lubricating oil additives with their use the pour point decreases, as shown in the Table 4.3. They are useful as plasticisers in synthetic (butyl) and natural rubbers when the hydrogenation percentage is below 30% 183). 

Use Plasticizer for cellulose acetate intermediate for antioxidants, special starches, oil-soluble phenolic resins pour-point depressors and emulsion breakers for petroleum oils and some plastics synthetic lubricants insecticides industrial odorants motor-oil additives. 

In some instances synthetic fluids are proposed for lubricating service on the basis of their resistance to degradation in a radioactive environment. These are likely to be unsubstituted or short-chain substituted polyphenyls or polyphenyl ethers. Their radiation stability outweights their disadvantages in other respects, such as high pour point and poor temperature coefficient of viscosity. 

Aromatic fractions can be alkylated with olefins to produce products which are used as synthetic lubricants.An aromatic fraction boiling between 160 and 210°C is generally alkylated with Cm to Cw olefins in a ratio of about 2 1. A higher-boiling aromatic fraction (boiling between 210 and 260°C) is reacted with Cs to Cw olefins in a ratio of 1 3. Aluminum chloride promoted with hydrogen chloride is the catalyst normally used. When the alkylated aromatics are blended with thickeners such as polyisobutylene, the mixture obtained is an excellent lubricant with a good viscosity index, stability, and pour point. 

Still there are efforts to improve the performance of natural mineral oil-based lubricants by the synthesis of oligomeric hydrocarbons, which has been the subject of important research and development in the petroleum industry for many years and has led to commercialization of a number of synthetic lubricants. These materials are based on the oligomerization of a-olefins such as C6-C20 olefins. Industrial research effort on synthetic lubricants has generally focused on improved viscosity index, thermal and oxidative stability, and a pour point equal to or better than that of the corresponding mineral oil lubricants. 

Synthetic lubricant with high viscosity 191 index and low pour point... 

After hydrogenation a synthetic lubricant obtained, with viscosity index of 104, a kinematic viscosity (at 100 °C) of 5 cSt, and a pour point of -3°C... 

Synthetic lubricating oils with low pour points and high viscosity indices are typically synthesised by oligomerisation of a-olefins, like 1-decene or 1-dodecene. hi 1997, BP showed... 

Polyisobutylene (PIB) fluids are produced by the oligomerization of isobutylene in a mixed C4 stream over a BF3 or AICI3 catalyst. PIB are seldom used by themselves. They are typically used as blend stocks or as additives to increase lubricant viscosity. Table 10 summarizes the typical properties of selected PIB fluids . The VI and pour points of PIB are comparable to those of conventional mineral oil. PIB usually have a lower flash point and decompose easily into monomer at 200°C and higher. The advantages of PIB are their high compatibility with most synthetic or mineral base stocks and their relatively low cost compared to other synthetic base stocks. 

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