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Intentionally adding water to oil, in the laboratory, provides an indication of the oil's ability to tolerate the presence of water. Various characteristics, such as emulsion, haze or separation, may be observed. Some blends of oil and water have been shown to form structures when left undisturbed. A visual, qualitative, storage test is capable of detecting this phenomenon as the presence or absence of structure. However, the time frame of formation can be on the order of days or weeks and is sensitive to handling and temperature effects. Quantitative methods are required for any evaluation of chemistry, temperature and handling effects on the rate and strength of structure formation. This paper describes rheological and electrical methods which directly and indirectly measure the tendency to form a structure at the molecular level, yielding rate of formation and strength information.

Viscosity Modifiers (VM's) are commonly sold as polymer in oil concentrates. Thus, the handling (pumpability and mixability) characteristics of these systems are important practical considerations. These VM's normally are characterized only by kinematic viscosity, although they are handled at a range of shear rates/stresses which kinematic viscosity does not describe. New polymer types and structures and the desire to make the modifier level as high as possible requires more than a single point kinematic viscosity measurement. The rheological behavior of the concentrate is required to make economical systems that can be handled in a practical manner. This paper represents an initial study of viscosity modifier concentrates by rheological techniques.