| Abstract: | 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. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3964–3975, 2004 |
