Self-healing glass fiber/epoxy composites with polypropylene tubes containing self-pressurized epoxy and mercaptan healing agents

To improve flowability of the healing agent released from micropipelines without manual intervention, this work prepared a proof-of-concept self-healing glass fiber/epoxy composite, in which plastic (polypropylene (PP)) tubes were embedded and used as containers of epoxy/mercaptan healing agent and foaming agent. Decomposition of the foaming agent at 70 °C created inflated gas in the sealed PP tubes in advance, which increased the internal pressure. Upon damage of the composite, the pressurized healing fluid burst out covering larger cracked plane and enhanced mixing of the liberated epoxy monomer and hardener. As a result, higher healing efficiency was observed as compared to the case without pressurization. The factors that influence healing performance of the system (e.g., tube spacing, content of the foaming agent, foaming time, etc.) were discussed in detail. The proposed approach is believed to have adequate expansibility and can be applied in other self-healing composites with micropipelines.