Temperature-dependent phase behavior in poly(ϵ-caprolactone)–epoxy blends

The cured morphologies of poly(ϵ-caprolactone)/epoxy (PCL/epoxy) blends are examined by SEM micrographs. The phase separation mechanism of the blend can be deduced from cured morphologies influenced by the blend compositions and curing conditions. The LCST phase diagram is proposed for the system and the location of the critical point shifts with the curing temperature, which results in the change of phase separation mechanism. The curing rate promoted by higher curing temperature also influences the morphologies of the blends. The fraction of the epoxy-rich macrophase resulted from the long-distance diffusion decreases with the increase of the curing temperature. In contrast, the domain size of the epoxy microphase increases with the curing temperature, which cannot be dominated by the epoxy curing rate.