by Joel Harrison
2. January 2011 20:45
A new technology is being developed by scientists at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen. The researchers are examining how carbon dioxide may be used to impregnate plastics to improve their characteristics.
They utilise the fact the gas goes into a supercritical state at a pressure of 73.8 bar and temperature of 30.1°C and becomes a solvent, which can be used as a carrier for numerous substances. CO2 is pumped into a special container with plastic and, for instance, a dye. When the temperature and pressure in the container are increased, the dye dissolves in CO2 and diffuses into the plastic. Subsequently, the container is opened, and the gas escapes, but the dye stays in the plastic.
The potential of the new technology is enormous. It makes it much easier to give new functions to plastics without harming the environment or increasing the costs of production.
Apart from dying coloured contact lenses, the new technology may be used to enrich contact lenses with medications, which would then be slowly released, making repeated application of eye drops unnecessary.
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