Synthetic lubricants volatility

Diesters. Many of the diester derivatives are commercially important. The diesters are important plasticizers, polymer intermediates, and synthetic lubricants. The diesters of azelaic and sebacic acids are useflil as monomeric plasticizing agents these perform weU at low temperatures and are less water-soluble and less volatile than are diesters of adipic acid. Azelate diesters, eg, di- -hexyl, di(2-ethylhexyl), and dibutyl, are useflil plasticizing agents for poly(vinyl chloride), synthetic mbbers, nitroceUulose, and other derivatized ceUuloses (104). The di-hexyl azelates and dibutyl sebacate are sanctioned by the U.S. Food and Dmg Administration for use in poly(vinyl chloride) films and in other plastics with direct contact to food. The di(2-ethylhexyl) and dibenzyl sebacates are also valuable plasticizers. Monomeric plasticizers have also been prepared from other diacids, notably dodecanedioic, brassyflc, and 8-eth5lhexadecanedioic (88), but these have not enjoyed the commercialization of the sebacic and azelaic diesters. 

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... 

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. 

PAO blended with mineral oil are also used in many partial synthetic lubricant formulations. In this case, PAO is used as a blending stock to improve the volatility, high or low-temperature viscosity, oxidative stability, etc. of the mineral oil blend. 

Graphite lubricants include the dry powder, admixtures with liquid lubricants or greases, volatile liquids compounded with film-forming substances to produce bonded dry films, synthetic resins and powder metal compositions containing graphite for bearings, and finely divided suspensions in liquids (colloidal graphite). 

Pressing is carried out within a cemented carbide die between two steel or cemented carbide punches. In order to impart enough mechanical strength to the blank to permit further manipulation without risk, removable organic binders (camphor, natural or synthetic waxes, latex or synthetic rubber, methyl polymethacrylate, polyvinyl alcohol, carboxymethylcellulose, ammonium alginate) are mixed into the powder, dissolved in a convenient volatile solvent. Some of these also act as lubricants thus minimizing the wear on the die. 

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. 

Table 2.7. Performance of synthetic and mineral lubricant oils. Relative evaluation of viscosity, stability (thermal, oxidation, hydrolytic, volatility), lubricity (wear protection and fatigue) and environmental impact...

The extrusion aid must easily coat the resin yet be readily removable from the extrudate. It should also not leave a residue which could alter the color of the product. The volatilization temperature of the lubricant should be lower than the sintering temperature of the polymer. The other requirements of lubricants include high purity, low odor, low polar components, high auto-ignition temperature, low surface tension, and low skin irritation. Common lubricants are synthetic isoparaffmic hydrocarbons available in a wide boiling range. Some of the commercial lubricants include Isopar solvents (available from Exxon Corp.), mineral spirits, and VM P Naphtha (available from Shell Corp.). 

Before the filament or staple is used in yam spinning, spin finishes are added to give lubricity and antistatic characteristics to the fibers and to provide a greater degree of fiber cohesiveness. Such finishes are usually mixtures including such materials as fatty acid esters, mineral oils, synthetic esters, silicones, cationic amines, phosphate esters, emulsifiers, and/or nonionic surfactants. Spin finishes are formulated to be oxidation resistant, to be easily removed by scouring, to give a controlled viscosity, to be stable to corrosion, to resist odor and color formation, and to be non-volatile and readily emulsifiable. 

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