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Morphology of polylactic acid crystallized during annealing after uniaxial deformation

Authors

  • Jean-Sébastien Hébert,

    1. Centre de recherche en matériaux avancés (CERMA) and Centre de recherche sur les matériaux fonctionnels (CQMF), Department of Chemistry, Faculté des sciences et de génie, Université Laval, 1045 Avenue de la Médecine, Québec, Québec, Canada G1V 0A6
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  • Paula Wood-Adams,

    1. Center for Applied Research on Polymers and Composites (CREPEC), Department of Mechanical and Industrial Engineering, Concordia University,1455 de Maisonneuve Blvd West, EV004.251, Montreal, Québec, Canada H3G 1M8
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  • Marie-Claude Heuzey,

    1. Center for Applied Research on Polymers and Composites (CREPEC), Department of Chemical Engineering, École Polytechnique de Montréal, P.O. Box 6079, Station. Centre-Ville, Montréal, Québec, Canada H3C 3A7
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  • Charles Dubois,

    1. Center for Applied Research on Polymers and Composites (CREPEC), Department of Chemical Engineering, École Polytechnique de Montréal, P.O. Box 6079, Station. Centre-Ville, Montréal, Québec, Canada H3C 3A7
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  • Josée Brisson

    Corresponding author
    1. Centre de recherche en matériaux avancés (CERMA) and Centre de recherche sur les matériaux fonctionnels (CQMF), Department of Chemistry, Faculté des sciences et de génie, Université Laval, 1045 Avenue de la Médecine, Québec, Québec, Canada G1V 0A6
    • Centre de recherche en matériaux avancés (CERMA) and Centre de recherche sur les matériaux fonctionnels (CQMF), Department of Chemistry, Faculté des sciences et de génie, Université Laval, 1045 Avenue de la Médecine, Québec, Québec, Canada G1V 0A6
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Abstract

Uniaxial deformation of amorphous L-polylactic acid films was performed at two different temperatures at which thermal degradation was minimal, 70 °C or Tg + 10 and 90 °C or Tg + 30. Samples were annealed postdeformation for long times (either 15 or 45 min) to approach equilibrium conditions. Samples deformed and annealed at 70 °C showed low crystallinity and poor crystalline order or crystal size, as determined by wide-angle X-ray diffraction. At 90 °C, high crystallinity and order parameters were observed. In addition, once the oriented chains had crystallized at this temperature, nonoriented chains also underwent crystallization, and a small fraction of nonordered crystal phase was therefore observed after long annealing times. These observations are explained on the basis of different morphologies in samples drawn at the two temperatures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013

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