Dielectric Spectroscopy of a Stretched Polymer Glass: Heterogeneous Dynamics and Plasticity
Caroline Crauste-Thibierge  1@  , Roberto Perez-Aparicio  1@  , Denis Cottinet  1@  , Loïc Vanel  2@  , Paul Sotta  3@  , Jean-Yves Delannoy  4@  , Didier Long  5@  , Sergio Ciliberto  1@  
1 : Laboratoire de Physique de l'ENS Lyon  (Phys-ENS)  -  Website
CNRS : UMR5672, École Normale Supérieure (ENS) - Lyon
46 allée d'Italie 69007 Lyon -  France
2 : Institut Lumière Matière  (ILM)  -  Website
CNRS : UMR5306, Université Claude Bernard - Lyon I (UCBL)
UMR5306 CNRS Université Claude Bernard Lyon 1 Domaine Scientifique de La Doua Bâtiment Kastler, 10 rue Ada Byron 69622 Villeurbanne CEDEX, Franc -  France
3 : Laboratoire Polymères et Matériaux Avancés  (LPMA)
CNRS : UMR5268, Solvay (France)
69192 ST FONS CEDEX -  France
4 : Laboratoire Polymères et Matériaux Avancés  (LPMA)  -  Website
CNRS : UMR5268, Solvay (France)
Plateforme Axel'One PMI 87, rue des frères Perret 69190 Saint Fons Cedex -  France
5 : Laboratoire Polymères & Matériaux Avancés, UMR5268, joined CNRS-Solvay Laboratory  (LPMA)
CNRS UMR 5268
85 rue des freres Perret – BP62 69192 Saint Fons Cedex -  France

We study the dielectric relaxation of polycarbonate (PC) at room temperature under imposed strain rate γ̇, above the yield stress, and up to 13% strain. We find that the dielectric response of stretched PC behaves as if it was heated up at a temperature just below its glass transition temperature, Tg around 423 K for PC. Indeed, in the frequency range of our experiment (10^–2 and 10^3 Hz), the dielectric response of the stretched PC at room temperature superimposes to the dielectric response of PC at a temperature T_a (gamma_dot) < Tg, which is a function of strain rate. Specifically we observe that at T_a the dominant relaxation time tau_alpha(T_a) of PC at rest is related to gamma_dot in such a way that tau_alpha(T_a) ∼ 1/gamma_dot at and beyond the yield point. In our experiment, 10^–5 s^–1 < gamma_dot< 10^–3 s^–1, the temperature shifts Tg – T_a are of a few kelvin. The mechanical rejuvenation modifies the dielectric response at frequencies smaller than 10 Hz, whereas for higher frequencies the spectrum is only slightly modified.


Online user: 1