ERJ staff report (DS)
Oberhausen, Germany -- Researchers at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen, Germany have come up with self-healing elastomers that can repair themselves, by stopping the growth of cracks
The source of their inspiration was the hevea Brasiliensis tree. Hevea latex contains capsules filled with the protein hevein. If the bark of the h. Brasieliensis tree is damaged, the latex escapes and the capsules break open to release hevein, which also links the rubber particles in the latex to close and seal the wound.
The scientists have applied this principle to elastomers. Dr. Anke Nellesen, who is a scientist at the Fraunhofer Institute for Environmental, Safety and Energy Technology, provides the explanation: â€œWe loaded microcapsules with a one-component adhesive (polyisobutylene) and put it in elastomers made of synthetic caoutchouc to stimulate a self-healing process in plastics. If pressure is put on the capsules, they break open and separate this viscous material. Then this mixes with the polymer chains of the elastomers and closes the cracks.
Various test bodies from different synthetic caoutchoucs indicated clear self-healing properties, since the restored tension expansion was 40 percent after a healing period of 24 hours.
The experts even achieved better results by supplying elastomers with ions. Here, the caoutchouc tree also acted as the model for this method. The hevein proteins that are released when there is damage link up to each other through ions and stick in this process so that the crack closes. Therefore, if the elastomer material is damaged, the particles with opposite charges are looking for a new bonding partner - in other words, a plus ion attracts a minus ion, which makes it adhere.
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Press release from Fraunhofer Institute