Viscosity cycloparaffins

Low temperature viscosities have an important influence on fuel atomisation and they affect engine starting. Cycloparaffinic and aromatic fuels reach unacceptably high viscosities at low temperatures. A kinematic viscosity of 35 mm /s (=cSt) represents the practical upper limit for pumps on aircraft, whereas much higher limits are acceptable for ground iastaHations. 

The chemistries of commercial oil vehicles vary with respect to the ratio of aromatic, paraffinic and cycloparaffinic carbon (generally about 20, 40, and 40 percent, respectively), degree of oxidation, and amount and character of impurities. The surface energies of the high and low viscosity ink vehicles shown in Figure 8 were 31.3, and 26.0 mN/rn, respectively (as measured by the Du NoUy ring method). 

In 1929 E. W. Dean and G. H. B. Davis,4 of Standard Oil, used this representation for viscosities to develop the VI concept for lubricant feedstocks, intermediates, and base stocks. In modified form, this method for describing the viscosity-temperature relationship for base stocks and lubricants has become one of the bedrocks of the industry. The VI of a base stock now immediately brings to mind, rightly or wrongly, other features of interest to lubricants professionals, for example, oxidation stability and chemical composition (e.g., content of isoparaffins and cycloparaffins), and more recently, volatility. It is, however, best to regard this method as a means to express the rheological properties (the science of flow) of a base stock and use other more specific tests to measure other properties. 

Comparison (Table 7.33) of compositional analyses on Yubase 6 with group I, II, and IV base stocks of similar viscosities shows the expected compositional differences—the Yubase 6 has a much higher isoparaffin content than either groups I or II and less 2+ ring cycloparaffins.44 The other benefits expected for group III stocks, namely higher flash point and decreased volatility as measured by the Noack test, also materialized. 

At the NBS, in addition to his polymer activities, he was also part of a large effort for the preparation and characterization of hydrocarbons within a molecular-weight range of 170 to 351, which comprised normal paraffins, cycloparaffins, aromatics, and fused ring compounds. The characterization included the pressure and temperature variation of density, viscosity, refractive index, and so on [Schliesser et al., 1956]. 

Seconds to 90% Cvap. Relative Rate nBuOAc = 1.0 Neat Viscosity cps 2S C Paraffins Cycloparaffins Tol EB c, Higher (excluding BB) Benzene Total Solubility Parameter... 

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