ENTANGLEMENT BEHAVIOR IN DYNAMIC BULK AND SHEAR PROPERTIES AS STUDIED BY ACOUSTIC METHODS

The effect of entanglements has been shown to contribute to dynamic bulk properties as well as to dynamic shear properties. The dynamic volume viscosity η′v has been estimated from measurements of longitudinal and shear waves by acoustic methods. The measurements have been performed in a frequency range from 103 to 108 Hz in solutions of polybutadiene and poly(ethylene glycols) of different molecular masses. The shape of the relaxation spectrum of the volume viscoelasticity conforms to that found by Doi and Edwards for shear properties. The relaxational bulk modulus has been calculated in the framework of Doi-Edwards theory. The ratio η′v η′s does not coincide with the theoretical value but appears to remain constant over a wide frequency range including that of entanglements. © 1990.