About the Extraordinary Frequency Behaviour of Ultrasonic Attenuation in Polymer Solutions

The abrupt change in the absorption of ultrasound by high polymer solutions with a small variation of frequency in the MHz range reported by Cerf et al. in 1961 is attributed to an effect of resonance. In the solution bigger and, with respect to the strictly separated fractions which were used, very regular aggregates are supposed to be formed. For the displacement of adjoining layers within these aggregates it is possible to explain the order of magnitude of the frequency for the abrupt change in the absorption. The calculation of the combined effect of several layers provides a solution, the structure of which is able to reproduce correctly the experimental results. Below a limiting frequency, a great number of resonant frequencies down to low frequencies are found. Above the critical frequency resonance is impossible, and the value of the absorption of ultrasound suddenly changes to a lower value.