Intrinsic Polydispersity, effect

In FFF, with a well-designed experimental setup, it can be demonstrated that the intrinsic sample polydispersity and nonequilibrium effect are the principal sources of peak dispersion [5]. The contribution to band broadening due to sample polydispersity is given by... 

The term in brackets on the left-hand side of Eq. (3-37) is called the intrinsic viscosity or limiting viscosity number. It reflects the contribution of the polymeric solute to the difference between the viscosity of the mixture and that of the solvent. The effects of solvent viscosity and polymer concentration have been removed, as outlined earlier. It now remains to be seen how the term on the right-hand side of Eq. (3-37) can be related to an average molecular weight of a real polymer molecule. To do this we first have to express the volume V of the equivalent hydro-dynamic sphere as a function of the molecular weight A/ of a monodisperse solute. Later we substitute an average molecular weight of a polydisperse polymer for M in the monodisperse case. 

If the drag reduction is small, we can argue, based upon the separation results of Berman and Yuen [3], that a very high molecular weight sample can be used to test for intrinsic drag reduction even if polydisperse. Then most of the molecules are effective throughout the Reynolds number range of the test. 

The branchii ratio g may be affected to some extent by the polydispersity of the sample The h%her the latter, the lower [ij], even if [ij] is related to M. This effect is rather weak, but might become strongly operative, if [p] were related to the number-average molecular weights. If the wei t-average molecular weights and intrinsic viscosities in a thermodynamically good solvent are used, the poly-... 

EFFECT OF POLYMER INTRINSIC VISCOSITY, MOLECUCULAR WEIGHT AND POLYDISPERSITY ON THE PROPERTIES OF THE MEMBRANES... 

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