Concerns about structural composites' long-term durability and reliability have seen them overlooked in aviation and transport applications. Yet they are lighter than the aluminium and other materials that find favour instead, so alleviating these concerns holds the potential for more fuel-efficient vehicles. A particularly innovative answer to this problem is the introduction of self-healing capability. While conventional adhesives have a part to play, it appears likely that specifically-developed high-value systems will be needed for this futuristic technology to come to fruition.
Materials that self-heal either consist of actual polymeric systems that are capable of repolymerising or composites containing components that will heal the overall system when damaged. The pure polymers are composed of relatively complex materials, for example a Diels-Alder polymerisation product of reaction between a multi-furan and multi-maleimide1 that chemically heals when heated. This article, however, will focus on composite materials that may use more common adhesives.