A multiple length scale description of the mechanism of elastomer stretching

J. Neuefeind, Anne Ladegaard Skov, J. E. Daniels, V. Honkimäki, Bo Jakobsen, Jette Oddershede, Henning Friis Poulsen

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Conventionally, the stretching of rubber is modeled exclusively by rotations of segments of the embedded polymer chains; i.e. changes in entropy. However models have not been tested on all relevant length scales due to a lack of appropriate probes. Here we present a universal X-ray based method for providing data on the structure of rubbers in the 2–50 Å range. First results relate to the elongation of a silicone rubber. We identify several non-entropic contributions to the free energy and describe the associated structural changes. By far the largest contribution comes from structural changes within the individual monomers, but among the contributions is also an elastic strain, acting between chains, which is 3–4 orders of magnitude smaller than the macroscopic strain, and of the opposite sign, i.e. extension of polymer chains in the direction perpendicular to the stretch. This may be due to trapped entanglements relaxing to positions close to the covalent crosslinks.
Original languageEnglish
JournalRSC Advances
Issue number98
Pages (from-to)95910-95919
Number of pages10
Publication statusPublished - 2016

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