Authors Basu, D. ; Das, A. ; Stöckelhuber, K.W. ; Jehnichen, D. ; Formanek, P. ; Sarlin, E. ; Vuorinen, J. ; Heinrich, G.
Title Evidence for an in situ developed polymer Phase in ionic elastomers
Date 22.05.2014
Number 42905
Abstract The overall mechanical performance of ionic elastomers, such as carboxylated nitrile rubber (XNBR), is largely governed by ionic clusters formed during the cross-linking of the elastomers with zinc oxide. These ionic aggregates promote microphase separation and show additional high-temperature relaxation behavior in dynamic mechanical analysis. In this study, the nature of these ionic aggregates is explored for the first time. We find that some zinc-containing compounds, such as zinc–aluminum-layered double hydroxide and zinc chloride, do not exhibit any extra high-temperature dynamic mechanical relaxation processes, although ionic cross-linking reactions with XNBR occur with all of these zinc compounds. Detailed analysis by Fourier-transform infrared spectroscopy and dynamic mechanical analysis revealed that this high-temperature relaxation behavior does not originate from ionic cross-linking but is associated with the formation of an additional zinc-enriched polymer phase that arises due to reactions between carboxylic groups and zinc oxide. Infrared spectroscopic investigation indicates further that a tetrahedrally coordinated complex facilitates the formation of a zinc–carboxylic polymeric network. Clear microphase separation of the ionic polymer in the elastomer could be directly visualized by transmission electron microscopy for the first time.
Publisher Macromolecules
Citation Macromolecules 47 (2014) 3436-3450
Tags carboxylated nitrile rubber sulfonated polystyrene ionomers butadiene-acrylonitrile rubber dynamic-mechanical properties zinc peroxide cross-linking viscoelastic behavior filler xnbr vulcanization

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