Composite Material Heals Itself With Bio Mimic

TECH SPACE

Graphic image manipulated from a scanning electron microscopic image. The ruptured capsule is red; the fracture plane is light blue. The chemical structure appearing to emerge from the capsule is the polymerized healing agent. The other chemical structure with red/green/gold is the structure of Grubb's catalyst.

Champaign - Feb. 19, 2001
Inspired by biological systems in which damage triggers an autonomic healing response, researchers at the University of Illinois have developed a synthetic material that can heal itself when cracked or broken.

The material -- consisting of a microencapsulated healing agent and a special catalyst embedded in a structural composite matrix -- could increase the reliability and service life of thermosetting polymers used in a wide variety of applications ranging from microelectronics to aerospace.

"Once cracks have formed within typical polymeric materials, the integrity of the structure is significantly compromised," said Scott White, a UI professor of aeronautical and astronautical engineering and lead author of a paper published in the Feb. 15 issue of the journal Nature that described the new self-healing material.

"Often these cracks occur deep within the structure where detection is difficult and repair is virtually impossible." In the new material, however, the repair process begins as soon as a crack forms.

"When the material cracks, the microcapsules rupture and release the healing agent into the damaged region through capillary action," White said. "As the healing agent contacts the embedded catalyst, polymerization is initiated which then bonds the crack face closed."

In recent fracture tests, the self-healed composites recovered as much as 75 percent of their original strength. And because microcracks are the precursors to structural failure, the ability to heal them will enable structures that last longer and require less maintenance.

"Filling the microcracks will also mitigate the harmful effects of environmentally assisted degradation such as moisture swelling and corrosion cracking," White said. "This technology could increase the lifetime of structural components, perhaps by as much as two or three times."

The ability to self-repair and restore structural integrity also could extend the lifetimes of polymer composite circuit boards, where microcracks can lead to both mechanical and electrical failure.

One of the many challenges the researchers faced in developing the material was obtaining the proper size of microcapsules. They currently use spheres about 100 microns in diameter. Larger spheres could have weakened the matrix, White said, and work continues on creating ever-smaller capsules.

"We also had to determine the correct shell thickness so the capsules would open under the appropriate stress," White said. "Capsule walls that are too thick will not rupture when the crack approaches, while capsules with walls that are too thin will break during processing."

In addition to White, the research team included theoretical and applied mechanics professor Nancy Sottos, aeronautical and astronautical engineering professor Philippe Geubelle, chemistry professor Jeffrey Moore, and graduate students Eric Brown, Michael Kessler, Suresh Sriram, and Sabarivasan Viswanathan. The work was sponsored by a UI Critical Research Initiatives grant.

TECH SPACE

Cornell Chemists Crack Crystal Bonding Mystery

Ithaca - September 14, 2000
In the 19th century, fundamental discoveries were made by unlocking the chemistry of carbon, but wide exploitation of these major discoveries came slowly. It took some years, for example, before this knowledge led to the development of new drugs and synthetic fibers.

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.