The MW obtained in this way, Mv, is higher that Mn and lower than Mw; sometimes Mv can reach values very close to Mw. An advantage of obtaining this average MW with capillary viscosimetry is that the equipment used (the viscometer) is very inexpensive in comparison to those used in other sophisticated techniques, and the measurements of flow time are very simple; the only drawback is the time consumed to prepare the samples at different concentrations and to run the samples in the glass viscometer, repeating the measurements a certain number of times.