Ultrasonic relaxation of poly(N-vinylpyrrolidone) and dextran in aqueous solution

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Abstract
The ultrasonic relaxation spectra of the polymers dextran and poly(N-vinylpyrrolidone) have been studied in aqueous solution over the frequency range 1–100 MHz. A range of molecular weights and concentrations were used to span dilute and semi-dilute solution conditions (0.44 < c[η] < 11). The results indicate that the relaxation spectra can be resolved into two components, one associated with the viscoelastic normal mode of the polymer chain and the other a significant contribution associated with more local conformational changes within chain segments.