Reduced viscosity is a concept used in the study of fluid dynamics and polymer science to describe the viscosity of a solution relative to its concentration. It’s typically applied to dilute solutions, like polymers dissolved in a solvent, to understand how the solute (polymer molecules) affects the solution’s flow behavior.
Key Points about Reduced Viscosity
Reduced viscosity essentially "normalizes" the viscosity contribution of the solute per unit of concentration, giving insight into the solute’s molecular properties, like size or shape, especially for polymers.
It’s often measured experimentally using tools like a viscometer and is a stepping stone to determining the intrinsic viscosity, which is the reduced viscosity extrapolated to zero concentration ( \(c \rightarrow 0\) ). Intrinsic viscosity is a key property for characterizing polymer molecular weight.
In polymer chemistry, it helps scientists understand how polymer chains interact with the solvent and each other.
Reduced Viscosity Formula |
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\( \mu_r \;=\; \dfrac{ \mu_i }{ c }\) (Reduced Viscosity) \( \mu_i \;=\; \mu_r \cdot c \) \( c \;=\; \dfrac{ \mu_i }{ \mu_r }\) |
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| Sumbol | English | Metric |
| \( \mu_r \) (Greek symbol mu) = reduced viscosiy | \(lbf - sec \;/\; ft^2\) | \(Pa-s\) |
| \( \mu_i \) (Greek symbol mu) = relative viscosity increment | \(lbf - sec \;/\; ft^2\) | \(Pa-s\) |
| \( c \) = mass concentration | \( lbm \) | \( kg \) |
