Eco-Friendly Plastics

Oxidation causes plastics to become brittle when exposed to air and light for extended periods of time, so manufacturers add antioxidant compounds called polyphenols to slow the process. Most of these stabilizers are petroleum derivatives, but a new polyphenol-rich “cocktail” made from grape skins, stems and seeds could provide an eco-friendly alternative.

Scientists took the leftovers from winemaking (called marc) and cooked it for 20 minutes in a microwave. The resulting liquid was then freeze dried and mixed into melted polypropylene – a plastic that is commonly used to make reusable containers. Compared to plastic with no added stabilizers, which cracked after 25 hours of exposure to air and ultraviolet light, the plastic treated with the grape stabilizers lasted twice as long. And when baked in a dark oven at 175 degrees Fahrenheit (80 degrees Celsius), the untreated plastic broke down after only seven hours whereas the grape-treated plastic lasted 94 hours.

The eco-friendly stabilizer still doesn’t work as well as the commercial petroleum-based stabilizers currently in use, and the developers caution that the results may be somewhat variable based on year-to-year changes in climate and growing conditions, which can affect the polyphenol concentrations in the marc. However, the fact that it utilizes biowaste instead of petroleum warrants further research.