Isothermal guest desorption from crystalline and amorphous phases of syndiotactic polystyrene

Isothermal desorption kinetics at different temperatures of 1,2-dichloroeth ane (DCE) from syndiotactic polystyrene films have been studied by Fourier transform infrared spectroscopy. For beta-form films, where DCE is present only into the amorphous phase, nearly equal populations of trans and gauche conformers, during the whole desorption processes, are observed. On the ot her hand, for clathrate films, where DCE is present in both amorphous and c rystalline phases, its trans conformer becomes largely predominant, as the desorption processes proceed. In agreement with previous FTIR and X-ray dif fraction studies, these results can be rationalized by assuming that essent ially only the DCE trans conformer is present in the clathrate phase. In th is assumption, experimental desorption kinetics from clathrate samples can be separated into faster processes from the amorphous phase and slower proc esses from the crystalline phase. The validity of this separation procedure is confirmed by the close similarity between the desorption kinetics obser ved for the amorphous phase of beta-form films and calculated for the amorp hous phase of clathrate films.