Mark–Houwink equation

https://doi.org/10.1351/goldbook.M03706
The equation describing the dependence of the intrinsic viscosity of a polymer on its relative molecular mass (molecular weight) and having the form: \[[\eta] = K\cdot M_{\text{r}}^{a}\] where [η] is the intrinsic viscosity, K and a are constants the values of which depend on the nature of the polymer and solvent as well as on temperature and M r is usually one of the relative molecular mass averages.
Notes:
  1. The use of this equation with the @R05271@ (@M04000@) is recommended, rather than with molar mass (which has the dimension of mass divided by @A00297@), since in the latter case the constant K assumes awkward and @V06600@ dimensions owing to the fractional and @V06600@ nature of the exponent a.
  2. Kuhn and Sakurada have also made important contributions and their names are sometimes included, as, for example, in the Kuhn–Mark–Houwink–Sakurada equation.
Source:
Purple Book, 1st ed., p. 64 (http://old.iupac.org/publications/books/author/metanomski.html)