Miscible binary blends of poly(ethylene oxide) and poly(ether sulfone). 2.Real-time small-angle X-ray scattering investigation of the semicrystalline morphology

Miscible blends of the crystallizable component poly(ethylene oxide) (PEO) and an amorphous component poly(ether sulfone) (PES) display a double melti ng behavior. The lower melting endotherm has been attributed to secondary c rystallization starting directly after the primary crystallization. The sem icrystalline morphology of these PEO/PES blends was studied in detail using synchrotron radiation. Real time small-angle X-ray scattering experiments performed during isothermal crystallization of the PEO/PES blends reveal th at secondary crystalline lamellae are formed between the primary lamellae a ccording to the lamellar insertion model. During melting of the secondary l amellae drastic changes occur in the SAXS patterns. On the basis of these o bservations, a model describing the semicrystalline morphology of PEO/PES b lends is proposed. The scattered intensity of PEO/PES blends after the melt ing of the secondary lamellae is interpreted in terms of a structure factor and a form factor. Model calculations on the form factor of the proposed s emicrystalline structure are in agreement with the observed scattering beha vior.