12/3/2023 0 Comments Viscosity chemistry meansOnce the value of K is known, the viscosity can be determined by measuring the amount of time the test liquid flows between the two graduated marks. Where \(K\) is the value of a liquid with known viscosity and density such as water. It's also likely proprietary, or at least the latest iterations probably are.\) Viscosity is defined as the measure of the resistance of a fluid to gradual deformation by shear or tensile stress. Self answering as it has been a number of months I'd still be extremely interested in the chemistry behind these VII's though I'd imagine that is incredibly complex hydrocarbons usually are if I'm not mistaken. in an engine) and lose their effectiveness. This blog also mentions that these VII's break down when sheared (so like. Oil, or 'thickens' it, which to some extent counteracts the decrease The process of mixing liquids to form an emulsion is called emulsification. Common examples of emulsions include egg yolk, butter, and mayonnaise. In an emulsion, one liquid contains a dispersion of the other liquid. Uncurls with the effect that it tends to restrict the motion of the An emulsion is a type of colloid formed by combining two liquids that normally dont mix. As the oil heats up, the viscosity index improver Has very little effect and the oil flows well as the base oil is a low Viscosity quantifies the internal frictional force between adjacent layers of fluid that are in relative motion. For liquids, it corresponds to the informal concept of 'thickness': for example, syrup has a higher viscosity than water. Thus when an oil is cold, the presence of the viscosity index improver The viscosity of a fluid is a measure of its resistance to deformation at a given rate. Of string when cold, but then uncurl as the temperature increases. Index improver is as a long chain molecule which curl up like a ball Light weight monograde oil), but include an additive called a Mineral multigrades use a light weight mineral oil (the same as a This is the method that determines the viscosity index of lubricating oils. So this is a gross oversimplification of this issue, however it is a very high level overview of the mechanism at work. Viscosity index means that it measures the change in viscosity with temperature a high viscosity index indicates a small viscosity change of a petroleum product with changes in temperature. Tiago Cousseau, “Film Thickness and Friction in Grease Lubricated Contacts: Application to Rolling Bearing Toque Loss,” PhD Thesis University of Porto (Universidade do Porto), Porto, Portugal, 2013.It is also nice to know how change of viscosity index by modifiers affect mono-grade oil to better multi-grade oil: The following graph illustrate how viscosity index influence the change of viscosity with temperature (Ref.1): Synthetic oils usually have a higher viscosity index than do mineral oils. The greater the viscosity index, the smaller the change in fluid viscosity for a given change in temperature, and vice versa. I have included some of graphs including SAE 5W-40, but failed to find the most common SAE 5W-30:įinally, for your information, Viscosity Index is a dimensionless number that represents how the viscosity of a hydraulic fluid changes with temperature. The company called Anton Paar has analyzed these SAE coded motor oil for the parameters, Kinematic viscosity and oil density versus elevating temperatures. The longer it takes, the higher the viscosity and thus the higher the SAE code. Viscosity characteristics: Kinematic viscosity is graded by measuring the time it takes for a standard amount of oil to flow through a standard orifice at standard temperatures. In chemistry, volatility is a material quality which describes how readily a substance vaporizes.At a given temperature and pressure, a substance with high volatility is more likely to exist as a vapour, while a substance with low volatility is more likely to be a liquid or solid. My (incorrect) understanding of this SAE nomenclature is that 5W means "Viscosity index of 5 in the winter" (or when really cold - like $\pu$). The motor oil in my 2004 Pontiac Vibe is 5W-30.
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