Mark–Houwink equation

The Mark-Houwink equation (also known as Kuhn- Mark-Houwink - Sakurada equation or Staudinger -Kuhn equation)

Is an empirically found the form of the relationship between two variables of a polymer, namely

• The Molmassenmittel M ( medium viscosity corresponds approximately to a weight average) and
• The intrinsic viscosity [ η ] ( Staudinger Index: limit of the reduced viscosity, extrapolated to a concentration and a shear rate of zero; experimentally determined by viscosity measurements at different polymer concentrations).
• K and α are constants that can not be accurately calculated theoretically and therefore must be determined empirically for each polymer-solvent pair.

In its logarithmic form

Is the equation commonly used to determine the Molmassenmittels a polymer from the Staudinger index.

The values ​​of K and α depend on the geometrical shape of the polymer ( hydrodynamic volume ) and thus of its interaction with the solvent. They are determined with the aid of calibration samples which should have a very narrow molecular weight distribution with a known viscosity agent. For many polymer - solvent pairs, the constants K and α are published in the scientific literature.