Title: viscosity function
Long Title: IUPAC Gold Book - viscosity function
DOI: 10.1351/goldbook.V06628
Status: current
Index: quantity

Definition
A coefficient connecting the intrinsic viscosity, the radius of gyration and the molar mass of a chain macromolecule, according to the equation: \[\rm{[}\eta \rm{]} = \frac{\mathit{\Phi }\ 6^{3/2}\ ( < s^{2} > )^{3/2}}{M}\] where \(\rm{[}\eta \rm{]}\) is the intrinsic viscosity, \(s\) is the radius of gyration and \(M\) is the molar mass. The viscosity function is often referred to as the Flory constant.

Related Terms
- coefficient: https://goldbook.iupac.org//terms/view/C01124
- intrinsic viscosity: https://goldbook.iupac.org//terms/view/I03140
- radius of gyration: https://goldbook.iupac.org//terms/view/R05121
- viscosity: https://goldbook.iupac.org//terms/view/V06627

Source
- Purple Book, 1st ed., p. 64 (http://old.iupac.org/publications/books/author/metanomski.html)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/V06628/html
- json: https://goldbook.iupac.org/terms/view/V06628/json
- xml: https://goldbook.iupac.org/terms/view/V06628/xml

Citation: Citation: 'viscosity function' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.V06628
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Accessed: 2026-07-15T06:27:12+00:00