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Title: A multiple length scale description of the mechanism of elastomer stretching

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. We find this may be due to trapped entanglements relaxing to positions close to the covalent crosslinks.
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [6]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division
  2. Technical Univ. of Denmark, Lyngby (Denmark). Danish Polymer Centre, Dept. of Chemical Engineering
  3. Univ. of New South Wales, Sydney, NSW (Australia). School of Materials Science and Engineering; European Synchrotron Radiation Facility (ESRF), Grenoble (France)
  4. European Synchrotron Radiation Facility (ESRF), Grenoble (France)
  5. Roskilde Univ., Roskilde (Denmark). Dept. of Sciences, Glass and Time
  6. Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Physics, Neutrons and X-rays for Materials Physics
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
RSC Advances
Additional Journal Information:
Journal Volume: 6; Journal Issue: 98; Journal ID: ISSN 2046-2069
Royal Society of Chemistry
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Danish National Research Foundation; Danish Natural Science Research Council
Country of Publication:
United States