Ultrasonic absorption in solutions of homo‐ and copolymers of vinyl chloride and vinyl acetate

Abstract

The ultrasonic attenuation in solutions of poly(vinyl chloride), poly(vinyl acetate) and different vinyl chloride/vinyl acetate copolymers dissolved in cyclohexanone was investigated. The results indicate that the relaxation spectra can be resolved by curves with two relaxation times. These processes can be explained by the presence of conformational changes of different degree of cooperativity. Comparison of the thermodynamic parameters with conformational energy calculations supports the assumption that the elementary process is a localized single‐bond process. The ultrasonic spectra of the homopolymers solutions are compared with those for statistical and graft copolymers.

Drag reduction and solvation in polymer solutions

“…DR takes place in highly dilute polymer solutions, and even there the existence of the connection is clearly visible in Brownian dynamics computer simulations, both static 8) and in flow 9) . Second, the importance of polymer + solvent interactions is demonstrated by ultrasonic absorption and shear viscosity studies of solutions of a number of homo-and copolymers by Alig, Wartewig and coworkers 10,11) . The role of the solvent shows up clearly also in the already classical work of Zakin, Hunston and coworkers (ZH) on DR [12][13][14] .…”

Ultraschalluntersuchungen zum Einfluß des Lösungsmittels auf die molekulare Beweglichkeit in Polymerlösungen

“…Ausgehend von Untersuchungen an Polyvinylchlorid (PVC) und Polyvinylacetat (PVAC) in Cyclohexanon [8,91 ist es das Ziel dieser Arbeit, den EinfluB verschiedener Losungsmittel auf die genannten Polymere rnit Hilfe der Ultraschallspektroskopie zu untersuchen. Dabei sol1 besonders der EinfluD der Losungsmittel auf die verschiedenen Bereiche des Ultraschallabsorptionsspektrums diskutiert werden.…”