Strain‐induced crystallization and mechanical properties of functionalized graphene sheet‐filled natural rubber |
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Authors: | Bulent Ozbas Shigeyuki Toki Benjamin S. Hsiao Benjamin Chu Richard A. Register Ilhan A. Aksay Robert K. Prud'homme Douglas H. Adamson |
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Affiliation: | 1. Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544;2. Department of Chemistry, State University of New York, Stony Brook, New York 11794;3. Institute of Materials Science, Polymer Program, University of Connecticut, Storrs, Connecticut 06269;4. Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269 |
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Abstract: | The effects of functionalized graphene sheets (FGSs) on the mechanical properties and strain‐induced crystallization of natural rubber (NR) are investigated. FGSs are predominantly single sheets of graphene with a lateral size of several hundreds of nanometers and a thickness of 1.5 nm. The effect of FGS and that of carbon black (CB) on the strain‐induced crystallization of NR is compared by coupled tensile tests and X‐ray diffraction experiments. Synchrotron X‐ray scattering enables simultaneous measurements of stress and crystallization of NR in real time during sample stretching. The onset of crystallization occurs at significantly lower strains for FGS‐filled NR samples compared with CB‐filled NR, even at low loadings. Neat‐NR exhibits strain‐induced crystallization around a strain of 2.25, while incorporation of 1 and 4 wt % FGS shifts the crystallization to strains of 1.25 and 0.75, respectively. In contrast, loadings of 16 wt % CB do not significantly shift the critical strain for crystallization. Two‐dimensional (2D) wide angle X‐ray scattering patterns show minor polymer chain alignment during stretching, in accord with previous results for NR. Small angle X‐ray scattering shows that FGS is aligned in the stretching direction, whereas CB does not show alignment or anisotropy. The mechanical properties of filled NR samples are investigated using cyclic tensile and dynamic mechanical measurements above and below the glass transition of NR. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 |
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Keywords: | composites crystallization graphene rubber WAXS |
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