Cavitation in Block Copolymer Modified Epoxy Revealed by In Situ Small-Angle X-Ray Scattering

Simultaneous small-angle X-ray scattering (SAXS) and tensile experiments were performed on epoxies modified with approximately 30 nm diameter rubbery and glassy core block copolymer micelles. The in situ SAXS data, interpreted using established analytical models, reveals efficient and coherent cavitation of the spherical rubbery cores coincident with yielding and absence of cavitation in the glassy nanodomains. These results are quantitatively anticipated by recent theory that accounts for cavitation in rubber toughened plastics as a function of particle size.