Viscosimetric-average molar mass

By using this kind of equation, it is possible to characterize a polymer by its intrinsic viscosity and to obtain its viscosimetric-average molar mass M. It is also possible to obtain the complete distribution of molar mass (DMM) by using Size Exclusion Chromatography and pure HFIP or a chloroform/HFIP 98/2 mixture as a mobile phase (eluent) (10,11). 

The molar mass determined with an [/jJ-M-relationship is the so-called viscosity average molar masses M, rather than mass (M ) or number average (MJ molar mass (see Chap. 2). This seems to be peculiar on first glance, since the molar masses used for the determination of the [ /]-M-relationships were either number or mass average molar masses (depending on the determination method). However, the samples used for the determination of the [/j]-M-relationship should have had a very narrow molar mass distribution. The unknown sample on the other hand has an unknown distribution function of the molar mass. Only in the case that the distribution function of the unknown sample and the sample used for the determination are the same, or M are determined directly from the viscosimetric measurement. 

In general a correction of the [/i]-M-relationship is not necessary for a heterogeneity class of A, since the error in this case is smaller than the general error of a viscosimetric measurement (for number average molar masses even [q]-M-rela-tionships of a heterogeneity class B do not need to be corrected). For all lower heterogeneity classes the correction must be done. 

The molar mass average determined with viscosimetric measurements is called... 

---