• Гідрологія і Гідрометрія
• Господарське право
• Економіка будівництва
• Економіка природокористування
• Економічна теорія
• Земельне право
• Історія України
• Кримінально виконавче право
• Медична радіологія
• Методи аналізу
• Міжнародне приватне право
• Міжнародний маркетинг
• Основи екології
• Предмет Політологія
• Соціальне страхування
• Технічні засоби організації дорожнього руху
• Товарознавство продовольчих товарів

A healing balm

Self-healing substances that are capable of repairing themselves when damaged are under development

One of the differences between animals and machines is that animal bodies can repair a lot of the damage that a cruel and hostile world inflicts on them. A machine, by contrast, has to wait for someone to come and fix it. But that may change if researchers in the field of self-repairing materials have their way. Two groups in particular - one in America and one in Britain - are trying to create composite materials that mend themselves if they get cracked, in much the same way that an animal's broken bone heals itself. The difference is that these materials will heal in minutes rather than months.

Such self-healing composites may take a while to enter everyday use. But if they can be made reliably they will be welcome in high-stress applications that are difficult to inspect regularly (the blades of wind turbines, for example) or are critical to safety (such as the doors and window-frames of aircraft).

Jeffrey Moore and his colleagues at the University of Illinois are working on the problem by adding extra components to their composites. Like most such materials, these composites consist of fibres (in this instance, carbon fibres) embedded in a plastic matrix (an epoxy resin). The main extra component added by Dr Moore is a sprinkling of tiny capsules containing a chemical called dicyclopentadiene. If the composite cracks, the capsules near the crack break open and release the dicyclopentadiene molecules, which link together to form another type of plastic that binds the crack together and thus heals the material.

To start with, Dr Moore had to nurse this process along by adding a second extra component—a catalyst based on ruthenium. This worked well in the laboratory, but ruthenium is too expensive for mass deployment. However, when he was playing with solvents that might be added to the system to speed the transfer of the dicyclopentadiene to the cracks it is intended to heal, he found a solvent that encouraged the process to work without the ruthenium catalyst. Alas, the solvent Dr Moore hit on, chlorobenzene, is pretty nasty stuff (it is used, for example, in the manufacture of DDT). However, he has since found a suitable alternative that turns out to be even better. The chlorobenzene process restored only 80% of a material's original toughness. The new solvents restore it completely.

The Economist

Make a presentation on advances in the sphere of self-repairing materials.

Переглядів: 480