Seminars

Damage in composite materials spans many length scales, is often difficult to detect, and is costly to repair. The incorporation of self-healing functionality in composite materials has the potential to greatly extend material lifetime and reliability. Although there has been remarkable progress in self-healing polymers over the past decade, self-repair in fiber-reinforced composite materials presents significant technical challenges due to stringent manufacturing and performance requirements. For high performance, fiber-reinforced composites, self-healing functionality needs to survive high temperature processing, reside in matrix interstitial regions to retain a high fiber volume fraction, and leave the mechanical properties of the material unaltered.

Here, solvent-based healing strategies are developed for incorporation in high performance fiber-reinforced composite materials. A method is developed to sequester healing agent-filled microcapsules (ca. 500 nm to 1 μm in diameter) at the fiber/matrix interface using a single fiber microbond specimen. Full recovery of interfacial shear strength after complete fiber/matrix debonding is achieved using a resin-solvent healing chemistry. The effects of capsule coverage, resin-solvent ratio, and capsule size on recovery of IFSS are also determined, providing guidelines for integration of this healing system into high fiber volume fraction structural composites. Ongoing research is aimed at expanding solvent-based healing strategies to thermoplastic-toughened epoxy matrices, which are cured at high temperatures.