Healing Plastic

Everyone has scraped or cut themselves at one point or another. Once a finger has an unfortunate encounter with the edge of a knife or your knee falls against rough pavement, exposed skin is damaged and you start bleeding. It’s all temporary, though. A scar is eventually all that is left from a painful injury.

Machines aren’t so lucky. Tiny cracks that form in all plastic structures widen over time. Fixing these cracks before they become an issue would increase the overall integrity of anything made from plastics. This isn’t an unrealistic concept: In 2001 aeronautics engineers at the University of Illinois developed a self-healing man made material. The idea was to eliminate microscopic cracks that form on a material’s surface.

The whole process works with the help of microcapsules filled with dicyclopentadiene (a liquid) that are dispersed throughout the plastic surface. These microcapsules rupture as soon as a crack reaches them. Once these capsules burst and release the diclopentadiene inside, the liquid comes into contact with a catalyst which turns the liquid into a more solid state while it fills the crack, thereby healing the plastic. The healed plastic is then about 80% as strong as it was before it acquired the (now healed) crack.
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Self-healing plastic hosts a microvascular network containing a healing
agent that automatically oozes in to repair cracks.
(Photo: National Science Foundation)

It may take a while before this technology is perfected but self healing plastics have obvious benefits: We tend to grow less interested in our gadgets as they get scratched up. If our cell phones or ipods stayed scratch free, we would probably hang on to them a lot longer. Not only that, but it would be incredibly practical to incorporate self healing plastics into structures that are difficult (and costly) to get to, such as satellites, wind turbines and the inside of complex machinery.

Self healing plastics have already evolved since 2001: The original researchers in Illinois have eliminated the need for the catalyst (thereby cutting down production costs) while Biswajit Ghosh and Marek W. Urban from the University of Southern Mississippi have also taken things a step further by developing a polymer that uses natural sunlight to repair itself. (Polyurethane networks have been proven to exhibit self-repairing tendencies with exposure to ultra-violet light.)Click for more information.

As a whole, I look forward to when my cell phone looks new for longer than a day.

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