Glass transition dynamics and structural relaxation of PLLA studied by DSC: Influence of crystallinity

J. F. Mano, J. L. Gómez Ribelles, N. M. Alves, M. Salmerón Sanchez

研究成果: ジャーナルへの寄稿学術誌査読

140 被引用数 (Scopus)


Poly(l-lactic acid), PLLA, in amorphous and semi-crystalline forms were studied by DSC, in order to investigate both molecular dynamics and structural relaxation features, and to understand the influence of the crystalline confinement on the segmental mobility of the intra-spherulitic amorphous phase. Experimental data were generated after submitting the materials to different thermal histories below Tg and were treated with a model based on the configurational entropy concept, allowing to extract a series of physical-meaningful parameters and to obtain the temperature dependence of the relaxation times. The main features of the relaxation process in the glassy state (activation energy of the glassy state and x) and the fragility index were found to be apparently insensitive to crystallinity. Significant differences between the two materials were detected in both the position of the glass transition temperature and the width of the distribution of relaxation times. In the framework of the Adam and Gibbs theory, it is suggested that for the semi-cristalline PLLA the mobility of the amorphous chains is more or less restricted, depending on their distance to the rigid lamellar walls or on the intra-lamellar thickness; this will imply that their conformational motions will take place at different temperatures, typically above the glass transition temperature of the (unconfined) bulk amorphous phase.

出版ステータス出版済み - 9月 8 2005

!!!All Science Journal Classification (ASJC) codes

  • 有機化学
  • ポリマーおよびプラスチック
  • 材料化学


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