Abstract
Self-healing composites are able to restore their properties automatically. Impressive healing efficiencies can be achieved when conditions are favourable. On the other hand, healing might not be possible under adverse circumstances such as very low ambient temperature. Here, we report a structural composite able to maintain its temperature to provide a sustainable self-healing capability—similar to that in the natural world where some animals keep a constant body temperature to allow enzymes to stay active. The composite embeds three-dimensional hollow vessels with the purpose of delivering and releasing healing agents, and a porous conductive element to provide heat internally to defrost and promote healing reactions. A healing efficiency over 100% at around −60°C was obtained. The effects of the sheets on the interlaminar and tensile properties have been investigated experimentally. The proposed technique can be implemented in a majority of extrinsic self-healing composites to enable automatic recovery at ultra-low temperatures.
Highlights
Self-healing composite materials are artificial materials that can heal after damage like living creatures do
A vessel-based design works in a similar way, but the capsules are replaced by a vascular network in one, two or three dimensions
The results indicate that the composite materials with either copper foam sheet (CFS) or carbon nanotube sheet (CNS) are able to self-heal at ultralow temperatures
Summary
Self-healing composite materials are artificial materials that can heal after damage like living creatures do. To enable a composite material to self-heal, capsule-based [2] and vessel-based designs [3] have been proposed. A vessel-based design works in a similar way, but the capsules are replaced by a vascular network in one, two or three dimensions By adopting these designs, FRCs endowed with the ability to self-heal have been created. Composites used on an aircraft may endure temperatures as low as −60°C, at which almost all healing liquids would be frozen and cannot be activated This has become one of the main barriers to the wider adoption of self-healing composites, prompting efforts to develop systems that can selfheal regardless of environmental and damage conditions. Experimental results indicate that the sheets reduced interlaminar strength but increased tensile properties
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