Autonomic healing of low-velocity impact damage in fiber-reinforced composites

In this study autonomic self-healing of impact damage in composite materials is shown using a microen-capsulated healing agent. The components for self-healing, urea-formaldehyde microcapsules containing dicyclopentadiene (DCPD) liquid healing agent and paraffin wax microspheres containing 10 wt% Grubbs' catalyst, have been successfully incorporated in a woven S2-glass-reinforced epoxy composite. Low-velocity impact tests reveal that the self-healing composite panels are able to autonomically repair impact damage. Fluorescent labeling of damage combined with image processing shows that total crack length per imaged cross-section is reduced by 51% after self-healing. A testing protocol based on compression after impact reveals significant recovery of residual compressive strength (RCS) in self-healing panels. Self-healing panels show a higher threshold impact energy before RCS reduction, and as impact energy increases. RCS recovery decreases. Qualitative inspection shows that crack separation increases with increasing impact energy, indicating that self-healing performance depends on the ability to adequately fill damage volume. (C) 2009 Elsevier Ltd. All rights reserved.