SMALL-ANGLE SCATTERING INVESTIGATIONS OF POLY(EPSILON-CAPROLACTONE) POLYCARBONATE BLENDS .1. SMALL-ANGLE NEUTRON AND X-RAY-SCATTERING STUDY OF CRYSTALLINE BLEND MORPHOLOGY

Crystalline morphologies of poly(epsilon-caprolactone) (PCL) and deuterated polycarbonate (d-PC) blends were studied by small-angle neutron and X-ray scattering (SANS and SAXS). Measurements were conducted at both room temperature and temperatures above the melting point (60-degrees-C) of PCL. Due to the different contrast between the phases for neutrons and X-rays, SANS exhibited a monotonic drop in intensity with increasing scattering angle while SAXS showed lamellar (peak) scattering. A two-correlation length model provided an excellent fit for the SANS data over the entire composition range. This model reproduced not only the shape but also the absolute magnitude of the scattering curves. The long range correlation length (approximately 10(2) angstrom) and the short range correlation length (approximately 10 angstrom) derived from this model are inferred to be associated with the crystalline PC domain and the local cluster in the amorphous phase (possibly resulting from crystallization-induced phase separation), respectively. Both the long range correlation length obtained from SANS and the long period measured from SAXS showed identical composition dependence. This further supports the applicability of the two-correlation length model and our interpretation.