Plastic made to be recycled

Researchers at Lawrence Berkeley National Laboratory in the US developed a type of plastic that was made to be recycled.

There are so many types of plastic available that even with the most state of the art plastic recycling systems, not everything can be separated. The use of additives like dyes, fillers and flame retardants do not make the recycling process any easier. Even the most recyclable plastic, PET, is only recycled 20 to 30 per cent of the time. The rest ends up in incinerators, on landfills, or, worst of all, in nature.

Most plastics aren’t designed to be recycled, only to serve their function. All plastics, from water bottles to automobile parts, are made up of large molecules called polymers, which are composed of repeating units of shorter carbon-containing compounds called monomers. Hard plastic often contains fillers to make them tough, and soft plastics plasticizers to make them flexible. These additives are tightly bound to the individual monomers the plastics consist of and stay in the plastic even it’s been processed at a recycling plant.

The new material, called poly(diketoenamine) or PDK, is designed to be disassembled onto its constituent parts at a molecular level using acid only to be reassembled. This reassembly can be done with in a different shape, with different texture or colour, without the loss of performance and quality. This means that PDK plastic can also be upcycled, instead of only downcycled.

The researchers next plan to develop PDK plastics with a wide range of thermal and mechanical properties for applications as diverse as textiles, 3D printing, and foams. In addition, they are looking to expand the formulations by incorporating plant-based materials and other sustainable sources.

Photo: Lawrence Berkeley National Laboratory