Rheological methods for determining molecular weight and molecular weight distribution

Abstract

Developments in rheological methods for determining molecular weight, polydispersity, and molecular weight distribution for linear polymers are described. The storage modulus and loss modulus are the starting points for many of the rheological methods used for determining molecular weight. The relationship between material parameters, molecular weight, and polydispersity is considered. For a linear polymer, the viscosity-molecular weight relation can be used to determine the weight average molecular weight by determining the limiting viscosity at zero shear rate. The relationship between material functions and molecular weight distribution is examined. Mixing rules describe how chains of different lengths influence one another. An example calculation of molecular weight distribution is presented.