Revealing the respective effect of aging and cyclic deformation through the memory effect in glassy polymers

It has been known for 40 years that the state of a glass cannot be characterized by a single parameter such as its density and depends on its whole thermal history in a complex way. This phenomenon, known as the memory effect, reveals that the spatial distribution of the dynamics in a glass is deeply heterogeneous. Among the various memory effects, we will focus on the following one. After an annealing at a temperature T, a glassy system will exhibit a specific signature of susceptibility - around the temperature T of annealing. This effect shows that relaxations during annealing occur only in some domains of specific dynamics. This has been observed in a variety of glasses, with different techniques. The memory effect, here, is observed for the first time through the dynamical elastic modulus. We show that the dynamical elastic modulus can be described by the simple phenomenological so-called Tool-Narayanaswamy-Moynhian (TNM) model. We evidence the competition between plastic deformation and annealing by applying cyclic strain during the annealing. As a result, we establish that deformation exhibits an effect that is opposite to thermal annealing and less selective in temperature.