https://doi.org/10.1351/goldbook.12220
The equation for viscosity-average molar mass is \[M_{\rm{v}} = \left[\sum\limits_{M} w_{M}M^{a} \right]^{1/a}\]
The equation for viscosity-average molecular weight is \[M_{\rm{r,v}} = \left[\sum\limits_{M_{\rm{r}}} w_{M_{\rm{r}}}M_{\rm{r}}^{a} \right]^{1/a}\] where \(a\) is the exponent in the Mark–Houwink equation, \([\eta] = KM^{a}\)
Notes:
- For definition of the symbols, see molar-mass average.
- Quantities viscosity-average molecular weight, viscosity-average relative molar mass, and viscosity-average relative molecular mass (\(M_{\rm{r,v}}\)) are synonyms. These quantities are dimensionless (pure numbers) and are not associated with any units.
- The exponent \(a\) is different from the adjustable parameter of some of the distribution functions and from the persistence length.