Remendable Interface in Glass Fiber-Reinforced Composites

Materials that can recover mechanical properties following failure offer increased safety and service life. The reversible Diels-Alder reaction of a furan with a maleimide was used to impart remendability at the polymer-glass interface for application in glass fiber-reinforced composite. Adhesion of the reinforcement to the polymer matrix is essential for load transfer from the polymer matrix to the reinforcement material in fiber-reinforced composites. An epoxy-amine network was furan-functionalized by the addition of furfuryl glycidyl ether as a comonomer and glass fibers were given malelimide functionality. At room temperature the Diels-Alder adduct is formed spontaneously and above 90°C the adduct breaks apart to reform the original furan and maleimide moieties. Healing of the interface was investigated with single fiber microdroplet pull-out testing. Following complete failure of this interface, significant healing was observed, with some specimens recovering over 100% of the initial properties. Healing efficiency was not affected by the distance of displacement, with an overall average of 46% healing efficiency. Up to five healing cycles were successfully investigated. It is expected that a glass fiber-reinforced composite of maleimide-sized glass within a furan-functionalized network will demonstrate extension of fatigue life.