Green Plastic Althernatives: Self-Healing Plastics and Renewable Polymers
Petroleum-based plastic has spent a long time near the top of green hit lists; however, recent innovations in bioplastics are providing exciting new alternatives. Scientists at Iowa State University are working on a new substitute for petroleum resins that could potentially outshine previous endeavors in the war on plastic. "Multifunctional renewable polymers" (aka self-healing plastics) have the ability to naturally repair themselves to prevent small surface cracks from becoming larger, permanent fractures. Also, a group at the Fronhaufer Institute in Germany is developing similar material inspired by the rubber tree.
In June, Associate Professor Michael Kessler of ISU received a $400,000 National Science Foundation CAREER Award for his research in self-healing plastics. Alonside his collaborator, Distinguished Professor Richard Larock, Kessler has made substantial progress demonstrating how polymers derived from vegetable oils are "excellent alternatives to petroleum-based resins for both environmental and economic reasons," according to Kessler in his NSF proposal. Kessler contends that polymers possess "great potential" for solving issues of micro-cracking and hidden damage. These may sound like minor concerns, but for lightweight composites used in aerospace structures, prevention could be life saving.
Kessler says the idea of self-healing plastic came to him as the result of a passing comment made by a seminar speaker visiting ISU. Later, Kessler mentioned the notion on a white board while brainstorming ideas with graduate students about potential topics for the NSF proposal.
Meanwhile, scientists at the Fraunhofer Institute in Germany are creating their own self-healing "elastomers." These advancements promise to increase the longevity of everyday objects as well as decrease energy consumption by various vehicles and machines. Inspiration for the self-healing elastomers came from the hevea brasiliensis rubber tree, whose sap is responsible for natural rubber and latex. When the bark of the tree is wounded capsules of a special protein break open and the latex works to seal the damaged area.
Fraunhofer scientist Anke Nellesen explains, "We loaded microcapsules with a one-component adhesive 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."
Tests implemented on a variety of synthetic caoutchoucs revealed self-healing properties, restoring tension expansion by 40 percent within 24 hours. When the researchers supplied the elastomers with ions, even more impressive results were achieved.
I couldn't find any information regarding exactly what the new technology will be applied to, but it's exciting news nonetheless. What would you like to see the technology put towards?