Researchers advance solvent-based recycling for flexible plastics
Baku, March 6, AZERTAC
Polypropylene and polyethylene are two durable and affordable plastics commonly used as packaging materials, snack wrappers, microwave containers, and other, usually flexible, plastic films, according to Phys.org.
Their flexibility, however, makes them resilient to recycling processes, and these plastics often end up in landfills or leak into the environment.
University at Buffalo researchers are leading efforts on a new, innovative way to repurpose these plastics through solvent-based recycling, or solvent purification. Their work has the potential to unlock for recycling millions of tons of plastics that are discarded or burned after use.
Polypropylene (PP) and polyethylene (PE) are polyolefins, some of the most common plastics used worldwide. More than 359 million tons of plastic were produced worldwide in 2024 alone, and polyolefins account for more than 50% of that weight, according to research in the journals Polymers and Cleaner Materials. Few solvents can dissolve polyolefins, making them one of the most efficient choices for protecting food, liquids and other materials. According to Paschalis Alexandridis, Ph.D., UB Distinguished Professor in the Department of Chemical and Biological Engineering, there is momentum in discovering ways to dissolve these plastics.
"There is interest in dissolving polyolefins, for example, during their processing and, more recently, for the purpose of plastics recycling," Alexandridis says. "To separate or isolate polyolefins from their mixtures or blends or multimaterial films, and to purify recycled polyolefins from additives, which are typically harmful to health."
Alexandridis and Marina Tsianou, Ph.D., professor, and Ali Ghasemi, Ph.D. student, both in the UB Department of Chemical and Biological Engineering; and Luis Velarde, Ph.D., associate professor in the Department of Chemistry, have co-authored recent papers describing ways to dissolve polyolefins and the potential benefits this method could have on alleviating plastic waste. In each paper, they introduce an experimental and modeling framework to address dissolution of different forms of polyolefins.
Scientists need to understand how PE and PP dissolve at microscopic levels in order to dissolve these plastics efficiently. The research team's work combines experiments with computer models to better understand the plastic behavior throughout the dissolution process. Despite being one of the most widely produced and used polymers, there have been just four articles published on PP dissolution since the 1970s.
Their study, "Polypropylene Dissolution Kinetics: Effects of Solvent, Temperature, and Particle Size," published in Polymers, describes their experimental findings as well as the new model they developed that is validated by the experimental findings. The researchers dissolved PP pellets—spheres of the polymers, also known as nurdles—across multiple solvents. They found that the pellets fully decrystallize before dissolving completely.
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