The morphology of a crystallizable polymer (PCL) in its compatible mixture with uncrys-tallizable polymer (SAN) has been investigated. The crystallinity of poly (e-caprolactone) (PCL) with poly (styrene-co-acrylonitrile) (SAN) has been measured with DSC. By means of cross- polarized optical microscopy and Hv light scattering

spherulites could be observed in the some PCL/SAN systems. The results from X-ray diffraction (WAXD) indicated that the unit cell dimentions of PCL are not changed due to the presence of SAN

but small angle X-ray scattering (SAXS) data showed that the long period between interlamellar regions incre-ases within increasing concentration of SAN. It is believed that the SAN molecules are trap-ped with the spherulites and rejected in interlamellar regions.