Rubber-modified epoxies: interfacial tension and morphology

The interfacial tension between carbomethoxy‐terminated butadiene–acrylonitrile copolymers and an epoxy resin as a function of temperature and copolymer composition is investigated. Using a digital image processing technique, the shape of a pendant drop of the epoxy in the copolymer is determined. Analysis of the drop shape is performed by profile discrimination and subsequent robust shape analysis. The data are used to examine the relationship between interfacial tension and particle size of the dispersed copolymer‐rich phase in rubber‐modified epoxy resins, that are immiscible in the uncured state.