Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-571-C8-574
Mechanical Spectroscopy of Side Chain Liquid Crystalline PolymersS. Etienne1, L. David2, P. Sixou3 and C. Laye3
1 Laboratoire de Métallurgie Physique et Science des Matériaux, UA 155 du CNRS, Ecole des Mines, Parc de Saurupt, 54042 Nancy cedex, France
2 Groupe d'Etude de Métallurgie Physique et Physique des Matériaux, Institut National des Sciences Appliquées de Lyon, 20 avenue A. Einstein, 69621 Villeurbanne cedex, France
3 Laboratoire de Physique de la Matière Condensée, UA 190 du CNRS, Université de Nice Sophia-Antipolis, Parc Valrose, 06108 Nice cedex 2, France
we report a low frequency mechanical relaxation study of molecular motions near and below glass transition in side chain liquid crystal polymers (SCLCP) in the cholesteric state. The SCLCP was a blend of crosslinked and uncrosslinked materials. Different compositions were studied. These materials exhibit low temperature relaxation processes and a main relaxation connected to the glass transition. Localised motions are responsible for the low temperature processes while the main relaxation exhibits cooperative features and is sensitive to the amount of crosslinked fraction. The relaxation time in the glass transition range when plotted against normalised reciprocal temperature shows that the molecular motions display a fragile character in agreement with the highly cooperative feature and strong physical aging effects. These observations are discussed in the frame of correlated motions involved in the liquid glass transition.
© EDP Sciences 1996