Adapted creep test for the study of non equilibrated thin polymer films Abstract: In a wide variety of applications preparation of thin polymer films involves a rapid transition from a solution into a dry glass. The limited time of this transition is insufficient for the polymer chains to reach an equilibrium state. Thus polymer chains are locked in out of equilibrium conformations accompanied by residual stresses in the film. These preparation induced non equilibrium conformations and the corresponding residual stresses in thin polymer films have two important consequences. First since the non equilibrium conformations tend to relax towards equilibrium the fabricated polymer film shows time dependent properties that can affect the performance reliability and durability of material components and devices. Second the polymer film shows properties deviating from the bulk equilibrium properties. However the origin of such deviations is not still satisfactorily unveiled. Deviations from the bulk behavior observed in thin polymer films have been also attributed to an increased molecular mobility at the polymer air interface which has a major contribution in thin films in comparison to the bulk due to the large surface to volume ratio. Therefore preparation induced residual stresses represent a persistent unsolved problem in polymers science and technology that has generated a lot of activities aiming at a better understanding on how to deal with how to tailor and how to manage such stresses in thin polymer films.<br><br>According to Albert Einstein: “Scientists investigate that which already is; engineers create that which has never been”. In order to “create that which has never been” we managed to clearly demonstrate the macroscopic consequence of residual stresses introduced into thin polymer films during spin coating process within this thesis. To this end we adapted the conventional creep test to filaments resulting from automatically crumpling thin films of polystyrene as a model polymer. We analyzed the changes in the length of filaments at temperatures above the glass transition temperature where both the residual stresses and the external applied stresses are expected to be comparable to the rubbery modulus of the polymer. The first key observation was found for an as cast film where a surprisingly rapid and large contraction of the filament in the creep experiment was observed. However a filament obtained from an annealed film showed an elongation in time the expected typical response of equilibrat ...