Healing plastic
Scientists at the University of Illinois at Urbana-Champaign, USA, have developed a self- healing plastic that could be useful in repairing cracked plastic items and in recycling plastics. Most composite materials, out of which a variety of things ranging from aircraft wings to circuit boards are made, consist of fibres of glass or carbon embedded in a matrix of polymer. These can develop cracks when subjected to stress and the cracks get bigger with the increase in strain. The scientists embedded tiny capsules of a liquid healing agent in the polymer matrix. When the crack increases it breaks the capsule thereby releasing the healing agent. The healing agent then comes into contact with a catalyst, also embedded in the matrix, and then polymerises. This polymer chain along the crack helps to bond the crack together. The cost of such a treatment might make it too expensive to use in ordinary materials but in certain specialized applications like prosthetics and satellites, it could prove to be invaluable ( Nature , Vol 40, p794).