Oils, lower viscosity

The first paint formulation corresponds to the initial formulation based only on alkyd resin (Table 3). In the second paint formulation, 20% of the alkyd has been substituted with vernonia oil. Lower viscosity is observed for this formulation. 

A certain minimum effective viscosity is required for complete displacement of mobile oil. Lower viscosity of the polymer bank displaces only part of the available mobile oil. 

Viscosity is measured in poise. If a force of one dyne, acting on one cm, maintains a velocity of 1 cm/s over a distance of 1 cm, then the fluid viscosity is one poise. For practical purposes, the centipoise (cP) is commonly used. The typical range of gas viscosity in the reservoir is 0.01 - 0.05 cP. By comparison, a typical water viscosity is 0.5 -I.OcP. Lower viscosities imply higher velocity for a given pressure drop, meaning that gas in the reservoir moves fast relative to oils and water, and is said to have a high mobility. This is further discussed in Section 7. 

The viscosity of the spray oil, as measured by the Saybolt test, also determines its safety on plants. Other properties being equal, oils of low viscosity ate safer to use on foHage than those of high viscosity. For dormant sprays on deciduous trees, oils with viscosities between 100 and 200 Saybolt universal seconds (SUs) at 37.8°C are considered satisfactory. A lower range is often used in colder and a higher range in warmer areas. 

Density Difference Between Particle and Liquid. Separation cannot take place if A6 = 0. Some mineral oils have the same density as water at room temperature. If it is heated to 80°C, the reduction of the density of water is less than that of the mineral oil, resulting ia the water becoming heavier. Therefore separation is possible. Dilution of a Hquid by a solvent, eg, molasses by water or heavy oil by naphtha, results ia lower density and lower viscosity of the Hquid. Solvent stripping takes place at a later stage. 

However, for the lubricants with lower viscosity, e.g.. Polyglycol oil 1 and 2 with the kinetic viscosity of 47 mm /s to 145 mm /s in Table 1, the transition from EHL to TFL can be seen at the speed of 8 mm/sand23 mm/s, i.e., the relationship between film thickness and speed becomes much weaker than that in EHL. The transition regime can be explained when the film reduces to several times the thickness of the molecular size, the effect of solid surface forces on the action of molecules becomes so strong that the lubricant molecules become more ordered or solid like. The thickness of such a film is related to the lubricant viscosity or molecular size. 

The contact ratios for lubricants with different viscosities are plotted in Fig. 37 as a function of speed. The decreasing rates vary significantly due to the difference in viscosities. For the maximum viscosity of tested oil 13606 (100 mm /s), the decreasing rate of contact ratio with speed is highest, and the contact ratio becomes zero at the speed lower than 2 mm/s. For the lower viscosity of lubricants such as oil... 

When the polar additive nonylic acid was added into hexade-cane liquid, the contact ratio becomes much smaller than that of pure hexadecane, which is shown in Fig. 39. For hexa-decane liquid, the critical speed to reach zero contact ratio is 50 mm/s, which is much higher than that of mineral oil 13604 because of its much lower viscosity. Flowever, when nonylic acid was added into the hexadecane liquid, the critical speed decreased from more than 50 mm/s to 38 mm/s. The same phenomenon can be seen in Fig. 39(h) which shows the comparison of oil 13604 and that added with 1.8 %wt. nonylic acid. The addition of polar additive reduces the contact ratio, too, but its effect is not as strong as that in hexadecane liquid because the oil 13604 has a much larger viscosity. Therefore, it can be concluded that the addition of polar additives will reduce the contact ratio because the polar additives are easy to form a thick boundary layer, which can separate asperities of the two rubbing surfaces. 

The viscosities of water and gasoline increase with decreasing temperature. Gasoline has lower viscosity than water, and fuel and crude oil have a much higher viscosity that increases dramatically when temperature decreases.32 The ease with which a fluid pours is an indication of its viscosity. It is observed that cold oil has a high viscosity and pours very slowly. The viscosity properties of various potential pollutants are discussed in Section 18.9. 

Compositional analysis shows a decrease in the percentage of polar compounds in the oils with increasing residence time (see Table II). The decrease in polar content is substantiated by a lower sulphur content and results in a lower viscosity (see Table II). The oil becomes more aromatic, as shown by n.m.r. spectroscopy (see Table II), with increasing time at temperature, while the molecular weights showed little change. G.l.c. analysis of the saturate hydrocarbon fractions from elution chromatography indicated little change in the saturates with residence time. 

It can be seen from Table I that the oil phase viscosity increases at a much slower rate than the polystyrene phase due to its lower reactivity at 80°C. Also, the volume of the polystyrene-rich phase is increasing at the expense of the oil-rich phase as styrene and polystyrene migrate to the polystyrene-rich phase. 

Pettersson and Sorensen have described a number of different thermoset resin structures based on hyperbranched aliphatic polyesters [123]. Their results can best be exemplified by a study on hyperbranched alkyd coating resins. A comparative study was performed between an alkyd resin based on a hyperbranched aliphatic polyester and a conventional high solid alkyd, which is a less branched structure. The hyperbranched resin had a substantially lower viscosity than the conventional resin of comparable molecular weight, that is, less solvent was needed to obtain a suitable application viscosity. The hyperbranched resin also exhibited much shorter drying times than the conventional resin, although the oil content was similar. These achievements would not have been possible without a change in architecture of the backbone structure of the resins (Figs. 12,13). 

At least one study has compared vemonia oil to partially epoxidized soybean and linseed oils, to investigate claims that vemonia oil is advantaged due to inherently lower viscosity. Authors conclude that partially epoxidized soybean and linseed oils have viscosity and reactivity that are similar to vemonia oil in formulated coating systems, and provide improvements to viscosity, content of volatile organic compounds (VOCs), and curing time in alkyd coatings when compared to conventional formulations and formulations containing fully epoxidized soybean oil [116]. 

The viscosity of residual fuel decreases rapidly with increasing temperature. If preheating is available, residual fuels atomize well. If preheating is not available, it may be necessary to bum lower-viscosity fuels rather than high-viscosity residual oils. 

Crude oil and high-boiling-point, high-viscosity petroleum fractions such as 6 fuel oil, atmospheric tower bottoms, and vacuum gas oil can contain wax which crystallizes at temperatures often above room temperature. It is not unusual for these oils to have base pour points of 100°F (37.8°C) or greater. In order to utilize these heavy oils, the pour point and viscosity of these oils must be reduced. One method which is used to accomplish this is to dilute the heavy oil with lower-viscosity components such as diesel fuel or kerosene. The oil then becomes pumpable at lower temperatures. 

The ease with which wax may be removed from oil-solvent mixtures depends to a large extent upon its crystal structure. The waxes present in the lower viscosity distillates tend to crystallize from oil-solvent solutions in very large crystals, while those in the higher viscosity distillates and residua form relatively small crystals. The size of crystal depends not only upon the nature of the oil fractions (34) but also upon the viscosity of the solution from which it crystallizes (41), and the manner in which the chilling is conducted. The character of the fraction may be controlled to some extent during the distillation process, and the viscosity of the medium from which the wax crystallizes may be regulated by addition of the solvent. Thus, the size of the crystal may be regulated to permit efficient separation of the wax from the oil-solvent solution. 

The viscosity of the external or oil phase plays a dual role. In an oil having a high viscosity (a high resistance to flow), a given amount of agitation will not break up the water phase Into droplets as numerous or fine as would be the case with a lower-viscosity oil. 

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