POLYMORPHISM OF SYNDIOTACTIC POLYSTYRENE - MORPHOLOGY OF THE SOLVENT-INDUCED CRYSTALLINE FORMS

The morphology of the delta and gamma forms of syndiotactic polystyren e (sPS) was investigated using scanning electron microscopy. The cryst alline forms, delta and gamma, characterized by the chains in helical conformation, were obtained by solvent-induced crystallization from th e amorphous glassy polymer. Dichloromethane and acetone were used to o btain the delta and the gamma form, respectively. The last form was ob tained by thermal treatments of the delta form, too. The surface of th e solvent-crystallized samples shows a texture characterized by orient ed elements and cavities, whereas the internal part is microspheruliti c in the case of the delta form and is more complex in the gamma form. At variance, the gamma form obtained by annealing the delta form show s a much more regular microspherulitic texture.