abstract
- We report on the rejuvenation of thin films of polystyrene (PS) as they are heated from stable glassy states, prepared either through vapor deposition or physical aging. For films with thicknesses h ≳ 200 nm and h ≲ 50 nm, the rejuvenation of vapor-deposited stable PS glass films is quantitatively described with zero free parameters by simulations using parameters previously obtained from isothermal rejuvenation measurements in the same material. For films with thickness h ∼ 140 nm, the behavior of the vapor-deposited films becomes more complicated and exhibits significant deviations from model predictions. After rejuvenation and physical aging, such films are then described by a single free parameter. The results of these studies suggest a new distinct mechanism that can result in rejuvenation of glassy PS, and hence two distinct relaxation processes that can couple to the material density.