Blending Effects In the Polymorphism of Syndiotactic Polystyrene Crystallized From the Quenched Amorphous Phase

The polymorphic behaviour of syndiotactic polystyrene (s-PS) is altered by blending with poly(2,6-dimethyl-1,4-diphenylene oxide) (PPO) when the former is crystallized from the quenched amorphous phase. In particular, while for pure s-PS samples disordered modifications of the alpha form (close to the limiting disordered alpha' modification) are obtained, more perfect modifications of the alpha form (closer to the limiting ordered alpha' modification) and the thermodynamically more stable beta form are obtained, for low and high PPO content of the blend respectively. On the basis of the present results, it is suggested that these substantial changes in the polymorphic behaviour of s-PS can be related to the large increases of the crystallization temperatures which are observed in the presence of PPO.