Effects of Branching and Molecular Weight Distribution

The influence of branching and molecular weight distribution on i)q, J°, and relaxation times in the terminal zone for concentrated solutions is qualitatively similar to that observed in undiluted polymers as described in Sections C4 and C5 of Chapter 13 but with some additional complications. 

In concentrated solution blends of two polymer components of different molecular weight at a constant total polymer concentration, i/o is determined by M of the polymer blend, while y is in general higher than that of either of the components. The dependence of y on blend proportions, and to some extent the time or frequency dependence of viscoelastic functions, can be described by a cubic blending law cf. Section C5 of Chapter 13). At considerably lower concentrations, however, a linear blending law is fairly satisfactory.  

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