ACS Publications Industry Webinar
The Viscosity of Oil
On-Demand
The viscosity of oils—the temperature dependence and blending behavior of organic liquids spanning a wide viscosity range—is important throughout the energy industry and beyond. While the understanding and prediction of viscosity has remained challenging, this webinar presents a fundamentally-based and simple framework that greatly simplifies the approach to viscosity and could be applied to a wide variety of oils, including those used in food science.
The temperature-dependent viscosity following a modified Arrhenius equation with two free parameters, η∞ and T₀ will be presented, as well as the rise in viscosity with decreasing temperature and the linkage to the glass transition, even at temperatures well above it.
The presented framework provides a unified approach to understanding and predicting the viscosity behavior of asphalt binders, lubricants, and polymer solutions used as viscosity modifiers. It simplifies the interpretation of industry specifications, supports blend design, and offers insights into the effects of pressure and oxidation. Guest speaker Dr. Eric Sirota will review examples of various materials and highlight limitations and open questions that are shaping future research directions.
Register to watch the webinar on demand.
SPEAKER
Eric B. Sirota, PhD
Research Scientist, ExxonMobil
After studying physics and music composition at Brown, Eric B. Sirota went to Harvard where he received his PhD in Physics in 1986, studying with Prof. Peter Pershan. He then joined Exxon(Mobil)’s Corporate Research lab in Clinton, New Jersey, as a postdoc, and never left. Realizing the importance of crystallizing alkyl-chain compounds throughout the industry, he first focused on establishing the fundamentals in that area. Eric became a Fellow of the American Physical Society for his pioneering use of x-ray scattering techniques in soft condensed matter, particularly regarding bulk and surface physics of alkyl chain compounds and of the physical properties of hydrocarbons and related materials. He expanded his interest to other physical properties, studying the fundamentals of asphaltenes and their phase separation and viscosity-related properties, which led him to extensive work on viscosity in general, and the subject of this webinar.
Eric is also an accomplished musical theatre composer/playwright, with his musical, Frankenstein, having played Off-Broadway for 3 years, adapted as an award-winning film.
RESEARCH SPOTLIGHT
Energy & Fuels 2025, 39, 30, 14511–14533
We present a framework for understanding and predicting the temperature-dependent viscosity of oil-based systems, based on the Modified-VTF equation η(T) = η∞exp{D/[(T/T0)-1]}, which relates to the approach to the glass transition, even at temperatures far above it. We present data showing that this applies to oils ranging from bitumen, resid, asphaltenes, and asphalt to highly fluxed, diluted, and less viscous systems such as diesel, as well as lubricants, model compounds, and polymers in solution, which could be viscosity modifiers or additives in lubes and asphalt. The key is to describe the η(T) behavior with two parameters: T0 and η∞, and to fix the fragility (D). These two parameters are shown to vary systematically with composition (i.e., MW and aromaticity) and vary systematically with chemical changes such as oxidation. Most significantly, this parametrization results in simple linear blending rules for those parameters, which can predict the observed highly nonlinear and sometimes nonmonotonic behavior.
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