ABSTRACT
Measurements of the frictional properties of dilute polymer solutions were amongst the earliest methods developed for determination of polymer molar mass and continue to be important today. Solution viscosity is by far the most extensively used frictional property, in part because it is very simple to measure accurately. Thus dilute solution viscometry, which is the principal focus for this chapter, remains a very widely practiced method for evaluation of molar mass and for specification of commercial grades of polymers. Historically, classical measurements of diffusion have been important, but nowadays diffusion mostly is observed using modern techniques, such as dynamic light scattering (Section 12.3) and specialized methods of nuclear magnetic resonance spectroscopy (Section 15.6). Sedimentation methods also have been used throughout the history of polymer science and, although mainly used to characterize biological macromolecules, they are having a renaissance for characterisation of synthetic polymers with the availability of modern analytical ultracentrifuges. Hence, in addition to a more complete description of dilute solution viscometry, a brief introduction will be given to polymer characterisation by ultracentrifugation.
