Freiburg, Germany - A team of researchers from the Institute of Macromolecular Chemistry of the University of Freiburg, Germany, is developing ways to produce polyurethane from citrus fruits.
Dr Rolf Mülhaupt and Moritz Bähr from the University of Freiburg, have developed a process to derive polyurethane from a naturally occurring substance called limonene, by reacting it with oxygen and carbon dioxide. Limonene is the main component of orange oil and is a by-product of orange juice production.
The researchers are the first to successfully react limonene oxide with carbon dioxide without use of solvents, according to a news release from the university. The resulting limonendicarbonat is pourable and can be cured with so-called amines, the researchers said.
The scientists also used the citric acid amidoamine as an amine hardener for the first time. The curing reaction produces polyurethane materials. Unlike conventional polyurethanes, no toxic intermediates are required, according to the research.
The Freiburg method is based on green chemistry. The team claim that it is neither toxic nor harmful for the environment and there are no by-products. Moreover, it does not compete with food production, as orange peel is a waste product in orange juice production and can be easily separated by extraction.
The polyurethane materials can be used in mouldings for interior and exterior trim of cars, as well as in thermal insulation and for new bio-based coating systems and adhesives.
This research was conducted in conjunction with Volkswagen.