Self-sealing of mechanical damage in a fully cured structural composite

A two part healing chemistry, stable to 150 °C, is incorporated in a woven glass/epoxy fiber-reinforced composite with a glass transition temperature (Tg) of 127 °C. The healing system is comprised of one type of microcapsules containing silanol end-functionalized polydimethylsiloxane, and a crosslinking agent, polydiethoxysilane, and a second type containing dibutyltin dilaurate catalyst in the solvent hexylacetate. The effects of microcapsule size and concentration on self-healing and mechanical properties including short beam strength, storage modulus and Tg were investigated. Self-healing of mechanical damage is assessed through the use of a pressure cell apparatus to detect nitrogen flow through a damaged composite. Complete self-healing was achieved when 42 μm diameter microcapsules at a loading of 9 vol.% or 25 μm microcapsules at a loading of 11 vol.% were added to the matrix.