Differential scanning calorimetry (DSC) was performed to investigate the cure behavior of epoxy networks of diglycidyl ether of bisphenol A/poly(ethylene oxide) (DGEBA/PEO) cured with 4,4'‐diaminodiphenyl sulfone (DDS). An interesting miscibility has been recently reported for DGEBA/PEO networks of a semi‐interpenetrating structure cured with aromatic amine. This study focused on the cure behavior and effects of miscible polymer diluents on cure kinetics. The physical miscible state between the polymer and epoxy was found to exert no alteration on the cure mechanism, which remained to be autocatalytic for DDS amine‐curing of all DGEBA/PEO mixtures as well as the pure DGEBA. The PEO component, being in a miscible state with the epoxy/DDS throughout the cure, acted as a diluent for the reactive DGEBA epoxy and DDS components. The dilution effect could be partially compensated by raising the DDS/epoxy ratio in proportion to increased PEO fraction in DGEBA/PEO/DDS mixtures.

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