Bob Michaels

December 8, 2010

2 Min Read
Self-Healing Shape-Memory Polymers Could Turn Everyone into a Terminator

Thermal image of a metal test specimen undergoing the photothermal heating method. (Image courtesy of American Institute of Physics)

Researchers at Arizona State University (Tempe) have created a material that may be able to sense damage in structural materials, such as cracking in a fiber-reinforced composite. The novel material may also be able to heal such damage. Undertaken by Michael Garcia, Yirong Lin, and Henry Sodano from the schools of mechanical, aerospace, chemical, and materials engineering, the research aims to develop such autonomous adaptive structures to mimic the ability of biological systems such as bone to sense the presence of damage, halt its progression, and regenerate itself.

As explained in the Journal of Applied Physics, the novel autonomous material uses shape-memory polymers with an embedded fiber-optic network that functions as both the damage detection sensor and thermal stimulus delivery system to produce a response that mimics the advanced sensory and healing traits exhibited by biological systems. An infrared laser transmits light through the fiber-optic system to locally heat the material, stimulating the toughening and healing mechanisms.

The material mimics the sensory system as well as toughening and healing mechanisms found in human bones. By incorporating both methods, the resulting autonomous material is 11 times tougher than the original material. In addition to becoming tougher, the material exhibits a shape-memory effect that can be used to close cracks. After a crack has been closed, the material recovers 96% of its original strength. Following crack closure the new material system has 4.9 times more toughness than the untoughened specimen, although it has been strained four times past its virgin failure strain. The material and healing process can be applied while the structure is in operation, which has not been possible with existing healing techniques.

The material could be used to create composites that are self-healing, halting the progression of cracks or damage and regenerating material wherever needed to restrengthen the structure.

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