Phase behaviour and borderline miscibility in blends of syndiotactic polystyrene with poly(vinyl methyl ether)

The state of miscibility and possible molecular aggregation in blends of semicrystalline syndiotactic polystyrene (s-PS) with poly(vinyl methyl ether) (PVME) were investigated by using differential scanning calorimetry (DSC), optical microscopy (OM) and scanning electron microscopy (SEM). The results are then directly compared to the classical amorphous PS/PVME blend prepared using exactly the same solvent and procedures. Similar to the classical amorphous a-PS/PVME, the semicrystalline s-PS/PVME exhibit the same scales of various molecular aggregation depending on composition leading to a so-called borderline miscibility, which is thoroughly discussed using the results of T-g-composition relationship and morphology evidence. The behavior of s-PS/PVME agrees mostly with that of a-PS/PVME, indicating that tacticity or crystallinity in s-PS does not affect the phase behaviour of s-PS/PVME in the amorphous domain. (C) 1999 Elsevier Science Ltd. All rights reserved.