Simultaneous memory effects in the stress and in the dielectric susceptibility of a stretched polymer glass
| Quand ? |
Le 21/09/2021, de 11:00 à 12:00 |
|---|---|
| Où ? | Salle des thèses |
| Participants |
Caroline Crauste |
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We report experimental evidence that a polymer stretched at constant strain rate λ̇ presents complex memory effects after λ̇ is set to zero at a specific strain λ_w for a duration t_w , ranging from 100 s to 2.2×10^5 s. When the strain rate is resumed, both the stress and the dielectric constant relax to the unperturbed state nonmonotonically.
The relaxations depend on the observable, on λ_w and on t_w . Relaxation master curves are obtained by scaling the time and the amplitudes by ln(t_w ). The dielectric evolution also captures the distribution of the relaxation times, so the results impose strong constraints on the relaxation models of polymers under stress and they can be useful for a better understanding of memory effects in other disorder materials.