Sedimentation measurements on polystyrene solutions in cyclohexane below the Flory theta temperature

Abstract

AbstractSedimentation measurements have been performed, at different temperatures below the Flory Θ temperature (a) on a series of monodisperse polystyrene samples in cyclohexane solution ranging in molecular weights from 8,5·104 to 1,1·106 and (b) on mixtures of the above samples. For the monodisperse polystyrene solutions it is found that the chain dimensions at the critical temperature are smaller than the unperturbed dimensions. For the solutions of the mixtures, the qualitative properties of the Johnston‐Ogston effect were studied. Furthermore, the measurement of the concentrations of each sample in the mixtures (neglecting the effect of the Johnston‐Ogston effect on the area of the peaks) has shown that the slow species is driven by the fast species, as the latter precipitates.