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French chemists have an ingenious new use for rotten, discarded wine grapes

You can trust the French, masters of wine that they are, to find amazing innovations involving grapes. That is what a team of researchers at the University of Clermont Auvergne have done with research which seeks ways to transform the waste grape skins, stems, and seeds left behind during wine production into more durable plastics.

“In France, doctors recommend drinking a glass of wine per day because it is rich in antioxidants,” researcher Audrey Diouf-Lewis told Digital Trends. “The wine industry transform 25 percent of the raw grapes into residue composed by seeds, grape marc, and lees, which are also rich in the same polyphenols. Thus we studied the potential of these molecules as novel biobased stabilizers for polymers.”

In the human body, polyphenols play an important role in preventing or reducing the progression of diabetes, cancer, and neurodegenerative and cardiovascular diseases. In plastics, meanwhile, they can help prevent similar reactions which have the effect of making plastics brittle after they have been exposed to the light and air for long periods of time.

For their research, the University of Clermont Auvergne scientists placed leftover materials from Pinot noir grapes into a microwave, before freeze-drying the resulting liquid to make it into a powder. This powder was then incorporated into the molecular matrix of melted polypropylene, a plastic which is frequently used for packaging and containers.

Tested under accelerated aging conditions, untreated plastics started to crack after just 25 hours. However, plastic which had been made using the grape residue lasted for more than twice as long. While Diouf-Lewis noted that their process is not as effective as some commercial stabilizers, it has the benefit of being more eco-friendly — and there is the potential to improve its performance in later research.

“These new bio-based additives will mainly be used to strengthen plastics and bioplastics intended for outdoor application, as they are exposed to sunlight,” she continued. “This is the case [for] garden furniture, car headlights or plastic packaging.”

In the future, she noted that the team aims to study the effectiveness of biowaste from other industries, such as byproducts from the wheat industry. A paper describing the work was recently published in the Journal of Applied Polymer Science.

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