Mechanical properties and linear infrared dichroism of thin films of polyurethane nanocomposites |
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Authors: | Lahorija Bistri?i? Mirela Leskovac Goran Baranovi? Sanja Lu?i? Blagojevi? |
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Affiliation: | 1. Department of Applied Physics, Faculty of Electrical Engineering and Computing, University of Zagreb, Unska 3, 10000 Zagreb, Croatia;2. Faculty of Chemical Engineering and Technology, University of Zagreb, Maruli?ev trg 19, 10000 Zagreb, Croatia;3. Rugjer Bo?kovi? Institute, P.O. Box 1016, 10001 Zagreb, Croatia |
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Abstract: | Morphological, mechanical, and Fourier transform infrared dichroic investigations were performed on neat polyurethane (PU) polymer matrix and PU+CaCO3 nanocomposite thin films to determine how the nanofiller influenced the mechanical properties. The measurements were performed on strips that were cut from the prepared films in parallel and perpendicular directions with respect to the direction of film preparation. Optical microscopy of PU and the PU+CaCO3 nanocomposite revealed the strain‐induced transition from a continuous spherulitic morphology to a fiberlike structure. The stress–strain behavior of the neat PU and PU+CaCO3 nanocomposite films showed significant differences at large strain regimes. The experimental results suggest that the mechanical properties were strongly related to the orientational behavior of the separated phases. The orientation of the hard and soft segments was analyzed by the orientation function calculated from the IR absorbances. A correlation between the orientations of segments, tensile properties, and hardness of the investigated polymer films was established. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 |
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Keywords: | FT‐IR nanocomposites orientation phase separation polyurethanes |
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