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A rheometer is a laboratory device used to measure the way in which a viscous fluid (a liquid, suspension or slurry) flows in response to applied forces.
Rheometry (from Greek ῥέος (rheos) 'stream') generically refers to the experimental techniques used to determine the rheological properties of materials, [1] that is the qualitative and quantitative relationships between stresses and strains and their derivatives.
Capillary breakup rheometry is an experimental technique used to assess the extensional rheological response of low viscous fluids. Unlike most shear and extensional rheometers, this technique does not involve active stretch or measurement of stress or strain but exploits only surface tension to create a uniaxial extensional flow.
Acoustic rheometer measures sound speed and attenuation of ultrasound for a set of frequencies in the megahertz range. These measurable parameters can be converted into real and imaginary components of longitudinal modulus. Sound speed determines M', which is a measure of system elasticity. It can be converted into fluid compressibility.
A dynamic shear rheometer, commonly known as DSR, is used for research and development as well as for quality control in the manufacture of a wide range of materials.. Dynamic shear rheometers have been used since 1993 when Superpave was used for characterising and understanding high temperature rheological properties of asphalt binders in both the molten and solid state and is fundamental in ...
It is often used for characterizing polymer solutions. Extensional viscosity can be measured using rheometers that apply extensional stress. Acoustic rheometer is one example of such devices. Extensional viscosity is defined as the ratio of the normal stress difference to the rate of strain. For uniaxial extension along direction : [2]
Rheology (/ r iː ˈ ɒ l ə dʒ i /; from Greek ῥέω (rhéō) 'flow' and -λoγία (-logia) 'study of') is the study of the flow of matter, primarily in a fluid (liquid or gas) state but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force.
It is a new way of doing rheology, traditionally done using a rheometer. There are two types of microrheology: passive microrheology and active microrheology . Passive microrheology uses inherent thermal energy to move the tracers, whereas active microrheology uses externally applied forces, such as from a magnetic field or an optical tweezer ...