Novel Experimental Approach To Evaluate Filler−Elastomer Interactions

• Published in: Macromolecules Vol. 43; no. 1; pp. 334 - 346
• Main Authors: Valentín, J. L, Mora-Barrantes, I, Carretero-González, J, López-Manchado, M. A, Sotta, P, Long, D. R, Saalwächter, K
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12-01-2010
• Subjects: Applied sciences; Composites; Exact sciences and technology; Forms of application and semi-finished materials; Physics; Polymer industry, paints, wood; Technology of polymers; Clay; SBR; Carbon black; Swelling; Coupled method; Natural rubber; Dispersion reinforced material; NMR spectrometry; Experimental study; Silica; Polymer filler interaction; Growth from solid state; Investigation method; Graphene; Nanocomposite
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma901999j

Novel information on filler−elastomer interactions is obtained by combining solid-state 1H low-field NMR spectroscopy and equilibrium swelling experiments. Multiple-quantum (MQ) NMR experiments provide detailed quantitative molecular information on the cross-link density of the elastomer matrix in a variety of filled systems, indicating generally weak filler effects on the overall cross-link density and on the network homogeneity. Swelling experiments, as well as mechanical data, are additionally influenced by the matrix−filler and filler−filler interactions. Our approach is based on comparing cross-link densities from NMR and (Flory−Rehner) swelling experiments, for which a masterline is always found in unfilled elastomers. In filled elastomers two different scenarios are observed. If there are no interactions between the polymer chains and the filler surface, no deviations from the masterline are detected because the swelling capacity of the composite is governed by the bulk polymer. Deviations from the masterline (reduced swelling) are exhibited by those composites that have strong rubber−filler interactions. In these cases, some fraction of the polymer is connected to the filler surface, which thus behaves like a giant cross-link, and the overall degree of swelling is thus reduced as compared to the bulk polymer. The novel experimental approach was used to evaluate filler−elastomer interactions in different composites and nanocomposites.