Tailoring the linear viscoelastic response of industrial double dynamics networks through the interplay of associations

Abstract

We investigate the linear viscoelastic properties of industrial pressure sensitive adhesives comprising double networks with an entangled acrylate-based polymer and two types of intermolecular associations (crosslinking), permanent (epoxide) and reversible (metal-chelate), having different compositions. A combination of shear rheometry and an appropriately modified version of the Time Marching Algorithm (TMA) allows to probe and analyze the behavior of the different double dynamic networks, in particular, the effects of the type and amount of crosslinks on their linear viscoelastic spectra. To this end, the dynamics of the double networks are compared with the respective individual responses of the polymeric component without crosslinks and the single networks (possessing only physical or only chemical crosslinks), in order to quantify their contributions to the relaxation mechanisms, particularly the interplay between disentanglement and bond association/dissociation processes. With the help of the TMA model, we also examine the respective roles of the lifetime of stickers, polydispersity, and molar mass. Triggered by the good comparison between predictions and experimental data, we propose a framework to tune material parameters in order to obtain a desired viscoelastic behavior.