Chain Degradation under Low-Intensity Sonication of Polymer Solutions in the Presence of Filler: Mechanism of Ultrasonic Degradation of Flexible Chain Macromolecules

Destructive changes of polymer matrices during preparation, storage, and mechanical testing of neat and C60‐filled polystyrene films

“…, to obtain good dispersion of nanotubes in polymer matrix without their destruction, shear stirring can be solely carried out in polymer melts with high viscosity. This recommendation contradicts our data obtained during low intensity sonication (in usual laboratory cleaning ultrasonic bath) of concentrated PS solutions containing either C 60 or carbon black . We have shown that even such gentle treatment resulted in decreasing polymer MW, but only in the presence of filler.…”

“…These ruptures occurred during swelling of samples and were accompanied by the following chemical reactions. We have also revealed that chain ruptures followed by postradical reactions took place after dispersing of both crystalline fullerene C 60 and carbon black in PS solutions by sonication in usual ultrasonic cleaning bath . The results obtained fitted well into universal mechanism of shear degradation formulated previously in our articles, where the necessary condition of chain degradation under the influence of stretching was the presence of entangled matrix interacting with surface.…”

“…Chain ruptures accompanied by the formation of macroradicals lead to irreversible changes in polymer matrix structure due to postradical reactions related to nature of the polymer. Products of destruction of PS chains forming in the presence of C 60 have been analyzed in our previous works . In short, during degradation of PS macromolecules, there is a probability of both numerous ruptures of the longest chains and recombination of some portion of macroradicals.…”

“…The commonly used method for dispersing of nanofillers in polymer matrices during preparation of composites is mixing them with polymer solutions or melts by ultrasound (U.S.). Additionally, for comparative tests, composite film PS‐2 + 8%C 60 was prepared by the “rapid evaporation” technique from concentrated PS‐2 solution that was mixed with crystalline C 60 by U.S. treatment for 35 h in laboratory ultrasonic cleaning bath …”

Dispersion and Localization Behavior of Modified MWCNTs in Immiscible Polymer Blends of Polystyrene and Polybutadiene and in Corresponding Nanostructured Block Copolymers

“…As discussed in literature, sonication can lead to significant polymer chain degradation already after only few minutes [28]. The degradation rate increases with higher polymer molecular weight [28][29][30] and with the presence of fillers [30]. Therefore, for the preparation of the BCP/CNT dispersions and films the procedure for the CNT dispersion was optimized in a way that varying MWCNT contents of 0.1-1.5 wt % (concentration related to the polymer) were pre-dispersed in the pure solvent for 10 min with the aid of ultrasonic treatment and were subsequently mixed with the BCP solution.…”