Mechanical Properties of Polyisoprene-Based Elastomer Composites

Deboleena Dhara, Md Anisur Rahman, Eric Ruzicka, Akshay Karekar, Dimitris Vlassopoulos, Kay Saalwächter, Brian Benicewicz, Sanat K. Kumar

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

We have explored the origins of mechanical reinforcement in elastomers filled with polymer-grafted nanoparticles (NPs). The brush chains are constructed from the same monomers as the polymer melt, although they have different microstructures (i.e., different amounts of trans and cis isomers). The NPs display a variety of morphologies depending on variations in the graft density of the polymers, with these morphologies hardly changing when the matrix (and the grafts) is cross-linked using dicumyl peroxide (DCP). NMR measurements show that the cross-link densities depend only on the DCP content and are independent of NP morphologies. We find that the elastic moduli of these materials are strongly dependent on the NP morphology but that the maximum reinforcement occurs when the NPs percolate, in a manner where the cores are exposed enough to have strong enthalpic interactions; these interactions could either be due to direct core-core van der Waals attractions or due to bridging interactions driven by polymers adsorbed on adjacent NPs. The nonlinear mechanical response of these materials is less sensitive to changes in NP morphology and loading. These results emphasize the important role of the exposed NP surface in determining the moduli of cross-linked elastomers. This last aspect is apparently less relevant for the corresponding uncross-linked melts filled with NPs.

Original languageEnglish
Pages (from-to)1448-1460
Number of pages13
JournalMacromolecules
Volume57
Issue number4
DOIs
StatePublished - Feb 27 2024

Funding

This work was supported by grant NSF (2124814).

FundersFunder number
National Science Foundation2124814

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