8 ITMP3 / 8éme conférence internationale de photoacoustique et photothermique
J. Phys. IV France 04 (1994) C7-241-C7-244
Application of photothermal mathods to the measurements of glass transition and viscoelasticity of polymersA. Cournoyer1, D. Lévesque2, L. Piché2 and L. Bertrand1
1 Department of Engineering Physics, Ecole Polytechnique de Montréal, C.P. 6079, Succ. Centre-Ville, Montréal, Québec, Canada, H3C 3A7
2 Industrial Materials Institute, 75 boulevard de Mortagne Boucherville, Québec, Canada, J4B 6Y4
The glass transition temperature Tg can be identified with a sharp increase of the thermal expansion coefficient X. We present photoacoustic and constrained photodeformation measurements of the glass transition in polystyrene in conditions of weak optical absorption. Since the thermoelastic contribution to the signal prevails in those conditions, we show both theoretically and experimentally that the signal amplitudes exhibit a sharp increase near Tg, allowing its clear identification and the observation of a viscoelastic behavior.
© EDP Sciences 1994