Behavior of concentrated polymer solutions under periodic stresses

Experimental methods for measuring the mechanical properties of concentrated polymer solutions and other viscoelastic systems under periodically varying stresses are reviewed. These include direct measurements of stress and strain, measurements of response at resonance frequencies determined by the inertia of the apparatus, propagation of waves in extended media, and measurements of resonance vibrations. The conditions for the suitability of each method are discussed, and equations for the interrelation of the various quantities measured are given. Examples are shown to illustrate the fitting of experimental data to the calculated behavior of mechanical models, in order to obtain frequency‐independent mechanical constants which can be interpreted in terms of molecular behavior.