Homogeneous nucleation temperatures for concentrated polystyrene/benzene solutions

Homogeneous nucleation temperatures for polystyrene/benzene solutions up to 60 wt% polymer have been measured. For polymer molecular weights from 17,500 to 100,000, homogeneous nucleation temperatures increase with increasing concentration from 226°C for pure benzene to 260°C for 60 wt% polymer. The experimental results have been compared to the predictions of homogeneous nucleation theory. It is concluded that for these solutions polymers affect the nucleation process principally through their effect on surface tension and solvent vapor pressure. For polystyrene solutions of molecular weight 600,000 or greater, a significant reduction in nucleation temperature was found. This phenomena appears to be caused by phase-separated domains in these high molecular weight solutions.