Structure and properties of the system: poly(2,6-dimethylphenylene oxide) isotactic polystyrene. Small-angle x-ray studies

Abstract

The superstructure of PPO/iPS blends, in which the iPS is partially crystallized from the glassy state by thermal treatment, is studied as a function of composition. A superstructure model, based on Hosemann’s treatment of a linear paracrystalline lattice, is used in order to calculate theoretical SAXS curves and fit them with experimental SAXS data. The model includes such superstructure parameters as lamellae thicknesses, thicknesses of amorphous regions, thickness distribution function, and size and shape of ’’ordered’’ regions. It is found that the lattice thickness distribution functions for both the crystalline lamellae and amorphous layers are best represented by symmetrical Gaussian functions. The thickness of the iPS crystal lamellae decreases with increasing PPO content. This explains, in part, the observed decrease of the melting point of the iPS in these blends.