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Most discarded plastic beverage bottles can be recycled—those imprinted with a number 1 within a triangular arrow. Yet the resulting second-generation plastic is generally unusable for making new containers. Now researchers have devised a way to manufacture plastic bottles that would increase their recycling life span.
The problem with bottles made from polyethylene terephthalate (PET) thermoplastic is that the manufacturing process often needs metal oxide or metal hydroxide catalysts. These catalysts linger in the recycled material and weaken it over time, making it impractical to reuse for a third generation. Instead second-generation PET ends up in less demanding applications, such as carpets and fiberfill for coats and sleeping bags. Or it ends up as trash. In the U.S., nearly 24 billion plastic beverage containers have been incinerated, dumped in landfills or discarded as litter within the first three months of this year, according to the nonprofit Container Recycling Institute in Culver City, Calif.
A team of scientists at the IBM Almaden Research Center in San Jose, Calif., and Stanford University reports in the February 16 Macromolecules that it has created a family of organic catalysts that could be used to make plastics fully biodegradable and recyclable. The researchers write that organic catalysts can rival even highly active metal-based catalysts while being environmentally benign. They also believe this research might lead to a recycling process that could break polymers back down into their constituent monomers for reuse.