Greenhouse gas finds new home inside plastics


Carbon dioxide gets as much bad press as plastics do, so it's nice to share a story in which both are the "good guys." Researchers at the Fraunhofer Institute say they have devised a process to impregnate plastics with carbon dioxide. Should it prove successful on a commercial scale, the process could prove a means to decrease the amount of greenhouse gas in the atmosphere while also improving certain properties in the impregnated plastics.

Researchers at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen, Germany are testing how carbon dioxide can be used to impregnate plastics. At a temperature of 30.1°C and a pressure of 73.8 bar, greenhouse gas CO2 goes into a supercritical state that gives the gas solvent-like properties. In this state, it can be introduced into polymers, or act as a carrier in which dyes, additives, medical compounds and other substances can be dissolved. "We pump liquid carbon dioxide into a high-pressure container with the plastic components that are to be impregnated, then steadily increase the temperature and the pressure until the gas reaches the supercritical state. When that state is reached, we increase the pressure further. At 170 bar, pigment in powder form dissolves completely in the CO2 and then diffuses with the gas into the plastic. The whole process only takes a few minutes. When the container is opened, the gas escapes through the surface of the polymer but the pigment stays behind and cannot subsequently be wiped off," explains Manfred Renner, a scientist at Fraunhofer UMSICHT....
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