Solvent-promoted self-healing epoxy materials

A study was conducted to demonstrate that cracks formed in epoxy-based thermoset materials can automatically be healed with organic solvents, recovering original mechanical integrity of materials. The healing mechanism involves wetting of the polymer surface and swelling of the bulk polymer material that leads to interlocking of the chains across the crack plane, which prevents crack propagation. Fracture testing of solvents was performed using tapered double cantilever beams (TDCBs). Solvents were injected onto the crack plane, which were allowed to heal for 24 h at room temperature (22°C). The healed TDCBs were loaded to failure, where the load-displacement curves was recorded. A healing efficiency based on the ratio of the healed peak load to the virgin peak load was also calculated. Results show that the autonomic self-healing system has recovered 82% of the materials' original fracture toughness.