Epoxy-aromatic diamine formulations are simultaneously modified with two immiscible thermoplastics (TPs), poly(ether imide) (PEI) and polysulfone (PSF), in concentrations ranging from 5 to 15 wt %. The epoxy monomer is based on diglycidyl ether of bisphenol A and the aromatic diamines (ADS) are either 4,4'-diaminodiphenylsulfone (DDS) or 4,4'-methylenebis(3-chloro 2,6-diethylaniline) (MCDEA). Using phase diagrams developed in Part I of this series, thermal cycles are selected to generate different morphologies. It is found that, whatever the AD employed, a particulate morphology is obtained when curing blends that are initially homogeneous. In the case of DDS-cured blends, a unimodal particle size distribution of PSF and PEI dispersed in a continuous epoxy-rich phase is observed. By contrast, the MCDEA-cured blends show a bimodal particle size distribution for all PSF/PEI relations that are analyzed. A completely different morphology, characterized by a distribution of irregular TP-rich domains dispersed in an epoxy-rich phase (double phase morphology), is obtained when curing blends that are initially immiscible. An X-ray analysis of the different phases makes it possible to determine their qualitative composition. The dynamic mechanical behavior of fully cured blends is also discussed. (C) 2004 Wiley Periodicals, Inc.