Synthetic lubricants viscosity

Lubricants, Fuels, and Petroleum. The adipate and azelate diesters of through alcohols, as weU as those of tridecyl alcohol, are used as synthetic lubricants, hydrauHc fluids, and brake fluids. Phosphate esters are utilized as industrial and aviation functional fluids and to a smaH extent as additives in other lubricants. A number of alcohols, particularly the Cg materials, are employed to produce zinc dialkyldithiophosphates as lubricant antiwear additives. A smaH amount is used to make viscosity index improvers for lubricating oils. 2-Ethylhexyl nitrate [24247-96-7] serves as a cetane improver for diesel fuels and hexanol is used as an additive to fuel oil or other fuels (57). Various enhanced oil recovery processes utilize formulations containing hexanol or heptanol to displace oil from underground reservoirs (58) the alcohols and derivatives are also used as defoamers in oil production. 

Synthetic lubricants are made with neopentyl glycol in the base-stock polyester (24). Excellent thermal stabiHty and viscosity control are imparted to special high performance aviation lubricants by the inclusion of polyester thickening agents made from neopentyl glycol (25,26) (see LUBRICATION AND lubricants). Neopentyl glycol is also used to manufacture polymeric plasticizers that exhibit the improved thermal, hydrolytic, and uv stabiHty necessary for use in some exterior appHcations (27). 

Synthetic lubricants are tailored molecules which have a higher viscosity index and a lower volatiUty for a given viscosity than lube oils from... 

Butyl mbber, a copolymer of isobutjiene with 0.5—2.5% isoprene to make vulcanization possible, is the most important commercial polymer made by cationic polymerization (see Elastomers, synthetic-butyl rubber). The polymerization is initiated by water in conjunction with AlCl and carried out at low temperature (—90 to —100° C) to prevent chain transfer that limits the molecular weight (1). Another important commercial appHcation of cationic polymerization is the manufacture of polybutenes, low molecular weight copolymers of isobutylene and a smaller amount of other butenes (1) used in adhesives, sealants, lubricants, viscosity improvers, etc. 

The plasticizer-range alcohols are largely used as feedstock for production of high molecular weight diesters of phthalic, adipic, azelaic, and sulftiric acids. All these are used primarily in plasticizers for polyvinyl chloride (PVC) and other plastics. The plastics industry also uses them as additives for heat stabilization, to control the viscosity of PVC plastisols, ultraviolet absorbers, flame retardants, and antioxidants. They are also found in synthetic, lubricants, agricultural chemicals, and defoamers. 

Polypheny I Ethers. Both alkyl-substituted and iinsubxtiinlcd polypheny ethers are included in this class of synthetic lubricants. General preparation involves the (.llhiian ether synthesis. The unsubstituted polyphenyl ethers have outstanding thermal, oxidative and radiation resistance, however, poor low-temperature characteristics arc a major drawback. Alkyl substitution improves low-temperature viscosity, but detracts from stability. Most lubricant uses are developmental in nature and involve aircrali and aerospace applications. 

The ideal diester for use in a partial synthetic lubricant, i.e. blend of diester, petroleum basestock and additives, should have the lowest viscosity at both high and low temperatures, and also be the least volatile. Of course, it would also need to be resistant to oxidation and corrosion and provide lubrication and wear protection when compounded into a finished lubricant. The low viscosity requirement of the synthetic portion of the partial synthetic lubricant is for economic reasons. The synthetic portion is substantially more expensive than the petroleum portion and the lower the amount required to achieve the low viscosity of the final oil, the better the final economics. As mentioned earlier, the low volatility is desirable to prevent carrying the... 

Plexor [Rohm Haas], TM for synthetic lubricants and additives for petroleum oils. Most grades are diesters of dibasic acids some are polyesters or polyether alcohols. The ester lubricants have very low freezing points, high flash points, little change of viscosity with temperature. 

Synthetic motor oils are made of a synthesized hydrocarbon base oil of hydrogenated polydecene, decanoic acid esters, zinc alkyl dithiophosphate, and synthetic poly alpha olefins. Most synthetic oils also contain additives, detergents, and corrosion inhibitors as well as viscosity modifiers. It is believed that the first synthesized polymeric hydrocarbons were synthesized in 1877, yet it was not until 1929 that the commercial development of synthetic lubricants was undertaken. Because of the availability of commercial petroleum-based lubricants, these synthetic lubricants were ultimately unsuccessful. The advent of commercial jet travel spurred the development of the first commercially successful synthetic lubricant, Mobil 1, in 1975. This lubricant had superior resistance to thermal breakdown and lower friction properties than petroleum-based products. 

ILs viscosity iuCTeased when the chain lengA of the side chain increases, the side chain is composed of fluoride or an imidazole ring in position 2 methylation, or there is increased cation symmetry. Generally, when the cation is composed of the thermally stable imidazolium ion, the anion determines the thermal stability of the entire IL, increasing in the order TfjN >BF >PF ">halogen ions. Minami et al. [18] studied thermo-oxidative stability and volatility of ILs and found that ILs have greater thermal stability than conventional synthetic lubricants. It was also found that the stability of an ILs depends on the structures of both the anion and the cation. For example, the stability of 1, 3-dialkyl-imidazoUum is more stable than quaternary ammonium. 

A further possible use is in the field of synthetic lubricants. The most likely use for the pyromellitate esters are as viscosity improvers(45), as the esters have quite high viscosities. They cannot be used at high temperatures, however, as at elevated temperatures they pyrolyse to form PMDA. There is an alternative use for PM LA in high temperature greases where pyrolysis is prevented by the formation of diimides, e.g. by reacting PMDA with p-aminobenzoic acid(46) and subsequently forming esters. Extreme pressure greases have also been claimed with the use of diimide derivatives(47). 

When the need for improved performance outweighs restrictions on price and desire for availability which ordinarily dominate the procurement of lubricants, then the purview expands to include fluids that can be made by synthetic chemistry. Even if we restrict ourselves to those fluids that promise reasonable potential for usefulness, there are as many as 20 broad generic classes which can come under consideration, and within each class there may be 10 or more subclasses gradated according to some property such as viscosity or molecular weight. A comprehensive survey of all the synthetic fluids with potential for practical use would be a major undertaking. In this chapter, therefore, we shall restrict ourselves to the examination of those types of synthetic lubricants that have been tested well enough to establish their usefulness and their limitations. 

Figure 17-2. Viscosity-temperature behavior of various types of synthetic lubricants. 1 White oil, VI 101. 2 4 -Undecy1-m-terphenyl. 3 Fluoroalkane. 4 -Di (chlorophenyl )pentane. 5 Polyphenyl ether. 6 Polyoxyalkylene glycol. 7 Di(2-ethylhexyl) sebacate. 8 Dimethyl silicone.

Sources Properties of Hydrocarbons of High Molecular Weight, Research Project 42, 1940-1966, American Petroleum Institute, New York J. Denis, The Relationship Between Structure and Rheological Properties of Hydrocarbons and Oxygenated Compounds Uses as Base Stocks, Journal of Synthetic Lubricants, vol. 1(1—3) 201—238 (1984) J. W. Nederbragt and J. W. M. Boelhouwer, Viscosity Data and Relations of Normal and Iso-Paraffins, Physica Xlll(6-7) 305-318 (1947) R. T. Sanderson, Viscosity-Temperature Characteristics of Hydrocarbons, Industrial Engineering Chemistry 41(2) 368-374 (1949). With permission. 

FIGURE 3.9 VI variation of pure compounds as a function of viscosity and structure. Source J. Denis, The Relationship Between Structure and Rheological Properties of Hydrocarbons and Oxygenated Compounds Used as Base Stocks, Journal of Synthetic Lubricants l(l-3) 201-238 (1984). With permission. 

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 improved viscosity index was prepared by oligomerization of the C10-C20 1-alkenes over catalysts containing a large pore zeolite with a high silica/alumina ratio. It was found that the reactivity of a-olefins followed the order of dodecene > tetradecene > hexadecene also, the internal olefins were less reactive than the corresponding a-olefins with similar carbon numbers, as also supported by O Connor. ... 

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