Dynamically Asymmetric Phase Separation and Morphological Structure Formation in the Epoxy/Polysulfone Blends

A thermoplastic polysulfone was used to blend with epoxy resin, and both the curing reaction and phase separation of the epoxy/polysulfone blend were investigated. Polysulfone did not alter the mechanism of curing reaction; however, it did depress the reaction rate. The details of the dynamically asymmetric phase separation, which was caused by the large differences in viscoelastic properties between epoxy and polysulfone component, were observed and studied. During the structure evolution, volume-shrinking behavior of the dynamically slow polysulfone component always existed even at fairly low (but still above the entanglement concentration) concentrations. More interestingly, when the curing temperature was higher than the glass transition temperature of polysulfone, volume shrinking with the consequence of layered structure formation was also observed as long as the viscoelastic asymmetry was maintained. These results indicated the generality of the mechanism of the dynamically asymmetric phase separation in this type of reactive system. Also, the influence of curing temperature was studied, and it was found that phase separation was promoted more than the curing reaction as the temperature was increased.