J. Phys. IV France 10 (2000) Pr7-299-Pr7-303
Dynamics NMR investigations of a glassy crystal confined in porous materialsR. Decressain, E. Cochin and L. Carpentier
Laboratoire de Dynamique et Structures des Matériaux Moléculaires, UPRESA 8024 du CNRS, Université de Lille 1, 59655 Villeneuve-d'Ascq cedex, France
The temperature dependence of the proton relaxation rates has ben studied in molecular glassy crystals cyano-adamantane (C10H15CN) confined in the porous space of a silica glass of 60Å and 150Å nominal pore sizes. In the temperature range corresponding to the bulk plastic phase, the NMR proton lineshape of the confined materials revealed a two phase system consisting of a liquid-like component and a crystalline solid bulk-like component. As for the bulk, the [Math] process, related to the dipolar axis motion, controlled both T1z and T1p in the largest pores. From the NMR results we concluded that the dynamics of this [Math]-relaxation process is slightly enhanced by the confinement giving rise to a negative shift of the glass transition temperature. On the contrary, the confinement has no influence on the relaxation rates in the glassy state.
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