Recycling plastic waste into carbon fibers

New Scientist : Amit Naskar and coworkers at Oak Ridge National Laboratory in Tennessee have found a way to convert the polyethylene in used plastic bags and other plastic waste into carbon fibers that can be fine-tuned for specific applications. Published in the journal Advanced Materials , their method involves mixing the polyethylene with polyactic acid, a compound derived from cornstarch or sugar cane. Then they heat the mixture and spin it into bundles of fibers 0.5â20 μm thick. Each fiber bundle is dipped into an acid-containing chemical bath, where it reacts to form a single black fiber that can’t melt even at very high temperatures. The heat, however, causes chemical components of the fibers to turn to a gaseous state, leaving behind a fiber composed mostly of carbon. By varying the process, the researchers can make fibers with different cross sections and porosities, which can be used for a variety of applications, such as filters for water desalination or lightweight composite materials for cars.