A new kind of plastic to cut landfill wastePlastics are divided into thermoplastics and thermoset plastics. The former can be heated and shaped many times and are ubiquitous in the modern world, comprising everything from children’s toys to lavatory seats. Because they can be melted down and reshaped, thermoplastics are generally recyclable. Thermoset plastics, however, can only be heated and shaped once, after which molecular changes mean they are "cured," retaining their shape and strength even when subjected to intense heat and pressure.
Due to this durability thermoset plastics are a vital part of our modern world. They are used in everything from mobile phones and circuit boards to the aerospace industry. But the same characteristics that have made them essential in modern manufacturing also make them impossible to recycle. As a result, most thermoset polymers end up as landfill. Given the ultimate objective of sustainability, there has long been a pressing need for recyclability in thermoset plastics.
In 2014 critical advances were made in this area with the publication of a landmark paper in Science announcing the discovery of new classes of thermosetting polymers that are recyclable. Called poly(hexahydrotriazine)s, or PHTs, these can be dissolved in strong acid, breaking apart the polymer chains into component monomers that can then be reassembled into new products. Like traditional unrecyclable thermosets, these new structures are rigid, resistant to heat and tough, with the same potential applications as their unrecyclable forerunners.
Although no recycling is 100 percent efficient, this innovation—if widely deployed—should speed up the move toward a circular economy, with a big reduction in landfill waste from plastics. We expect recyclable thermoset polymers to replace unrecyclable thermosets within five years, and to be ubiquitous in newly manufactured goods by 2025.
Source: Scientific American
No comments:
Post a Comment