Correlated and cooperative motions in segmental relaxation: Influence of constitutive unit weight and intermolecular interactions.

Rijal, Bidur; Soto Puente, Jorge Arturo; Atawa, Bienvenu; Delbreilh, Laurent; Fatyeyeva, Kateryna; Saiter, Allisson; Dargent, Eric · Phys Rev E · 2016

basic_science · Level V

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Abstract

This work clarifies the notion of correlated and cooperative motions appearing during the α-relaxation process through the role of the molecular weight of the constitutive units and of the interchain dipolar interactions. By studying amorphous copolymers of poly(ethylene-co-vinyl acetate) with different vinyl acetate contents, we show that the correlated motions are not sensitive to the interchain dipolar interactions, in contrast to the cooperative motions, which increase with a strengthening of the intermolecular interactions for this sample family. Concerning the influence of the molecular weight m_{0}, the notion of "correlated motions" seems to be equivalent to the notion of "cooperative motions" only for low m_{0} systems.