Since the 1970s, the generation of plastic waste has steadily increased. Discarded plastic continues to accumulate in our oceans, harming wildlife and contributing to climate change.
However, there are many hurdles to recycling plastic. The few plastics that are recycled often have to be processed using high temperatures and toxic chemicals. Now scientists are trying to find mild and environmentally friendly ways to recycle plastics. An international team of researchers led by chemistry professor Christophe Thomas at PSL University in France recently discovered a green method to convert nitrile rubber—a common plastic used in hoses, footwear, and adhesives—into new, renewable plastics.
The researchers’ process involves two major steps. First, the particles that make up nitrile rubber need to be broken down. A ruthenium-based catalyst called Zhan-1b chops nitrile rubber polymer chains into smaller pieces. This degradation step is fairly quick; in under an hour, all of the original rubber breaks down. Then, the researchers add environmentally friendly carboxylic acids to the reaction mixture. The fragments from the first step merge with the carboxylic acids to produce unsaturated polyesters. Unsaturated polyesters are found in glass fiber-based composites and coatings, making them important in the construction industry. Thus, nitrile rubber can take on new life as a bike frame or paint.
The researchers’ reaction pathway has great promise for recycling nitrile rubber. “The advantages of this process are numerous—it is inexpensive, as it employs commercially available catalysts at a low cost, and all steps occur within the same vessel, minimizing waste and solvents and maximizing efficiency,” Thomas said. The team is seeking ways to modify their process to recycle plastics similar to nitrile rubber, in hopes of producing other sustainable materials.
Image courtesy of Pixabay.