ABSTRACT
This chapter focuses on the measurement of liquid molecular weights only. Some of the instruments used in the measurement of the molecular weights of larger molecules, such as viscometers or gel-permeation chromatographs, are treated in separate sections. However, an average molecular weight or a molecular weight distribution can be determined, and these are useful in predicting the physical properties of the polymer. The resultant temperature difference, due to the latent heat of the solvent, can be related to the molecular weight of the solute. The instrument is limited to low-molecular-weight polymers because of the small difference in temperature involved. If molecular size approaches the wavelength of light used, the light is scattered by portions of the molecule which are widely separated. Viscosity measurements are made of a well-fractionated or monodisperse polymer whose molecular weight is known or has been measured by some other method.
