Viscosity and low

Heavy oil is another type of petroleum, different from conventional petroleum insofar as the flow properties are reduced. A heavy oil is much more difficult to recover from the subsurface reservoir. These materials have a high viscosity and low API gravity relative to the viscosity and API gravity of conventional petroleum (Fig. 1) (3,4), and recovery of heavy oil usually requires thermal stimulation of the reservoir. 

This low viscosity resin permits cure at low (70°C) temperatures and rapidly develops excellent elevated temperature properties. Used to increase heat resistance and cure speed of bisphenol A epoxy resins, it has utihty in such diverse appHcations as adhesives, tooling compounds, and laminating systems. A moleculady distilled version is used as a binder for soHd propellants (see Explosives and propellants) and for military flares (see Pyrotechnics). Its chief uses depend on properties of low viscosity and low temperature reactivity, particularly with carboxy-terminated mbbers. 

Solvents which are kinetically stable with lithium show either high viscosity and high permittivity, or low viscosity and low permittivity. The diminution of high viscosity of solvents such as PC or EC is accom-... 

The melt index (MI) or melt flow index (MFT) is an inverse measure of viscosity. High MI implies low viscosity and low MI means high viscosity. Plastics are shear thinning, which means that their resistance to flow decreases as the shear rate increases. This is due to molecular alignments in the direction of flow and disentanglements. 

Molecular Rotational Diffusion. Rotational diffusion is the dominant intrinsic cause of depolarization under conditions of low solution viscosity and low fluorophore concentration. Polarization measurements are accurate indicators of molecular size. Two types of measurements are used steady-state depolarization and time-dependent (dynamic) depolarization. 

Comparison of mechanical and processing properties with morphology shows that the formation of a network structure is the desired morphology for high impact strength, low viscosity and low shrinkage as indicated in Figure 6 for the impact behavior.12... 

Polycondensation polymers such as PET are characterized by low melt viscosities and low melt strengths. Furthermore, with PET there is a marked shear liquefaction... 

Hydraulic fluid a fluid supplied for use in hydraulic systems. Low viscosity and low pour point are desirable characteristics. Hydraulic fluids may be of petroleum or nonpetroleum origin. 

Primary and secondary aliphatic polyamines These are low viscosity and low cost materials. In general, linear and branched primary and secondary aliphatic... 

Liquids obtained from different petroleum reservoirs have widely different characteristics. Some are black, heavy, and thick, like tar, while others are brown or nearly clear with low viscosity and low specific gravity. However, nearly all naturally occurring petroleum liquids have elemental analyses within the limits given in Table 1-3. 

Practical considerations call for a liquid of high viscosity and low vapour pressure and a low solubility in water. A solution of a calcium complex with a dialkylphosphoric acid (e.g. ((RO)2POO)2Ca, where R = C8Hi7 to C16H33) in a very polar solvent such as di-n-octylphenyl phosphate can be used in an ion-selective electrode that gives a linear response over 101 [Ca2+]... 

For many applications low-temperature flexibility of the plasticized composition is also important. Plasticizers of low viscosity and low viscosity-temperature gradient are usually effective at low temperature. There is also a close relationship betv/een rate of oil extraction and low-temperature flexibility plasticizers effective at low temperature are usually rather readily extracted from the resin. Plasticizers containing linear alkyl chains are generally more effective at low temperature than those containing rings. Low-temperature performance is evaluated by measuremen t of stiffness in flexure or torsion or by measurement of second-order transition point, brittle point or peak dielectric loss factor. 

Excessive load, reduced fluid viscosity, and low speed can cause a breakdown of the lubrication layer to the point of a metal-metal contact. Direct adhesive contact can lead to molecular interaction strong enough to tear material out of the surface. This process is also known as cold welding . Metal surfaces under ambient conditions are usually covered with oxide layers that prevent cold welding at moderate loads. 

Use a lower viscosity grade oil to reduce fluid friction under high speed driving conditions at low temperatures. Low-viscosity and low-volatility base oils, such as poly-a-olefin PAO or hydrorefined base oils, are necessary for the next generation of fuel-saving engine oils, such as those required to meet specification... 

---