Recently, some scientists have tried to embed an enzyme in plastic, so that the plastic can quickly decompose without producing microplastics.
Just by adding a small amount of polymer-chewing enzymes to the plastic, you can make plastic bags and plastic forks biodegrade to the point where they can be composted!
Experts say that at moderate temperatures, under standard composting conditions, or in ordinary tap water, plastic films with added enzymes can break down within days to weeks.
"Biodegradability is not the same as compostability." said researcher Xu Ting. She often finds bits and pieces of biodegradable plastic in her garden compost.
Most biodegradable plastics end up in landfills, but the conditions in landfills are not suitable for degradation, so they degrade no faster than ordinary plastics.
Previously, embedding polymer-chewing enzymes into biodegradable plastics accelerated their breakdown. But often, potentially harmful “microplastics” are formed unintentionally and are found in ecosystems around the world.
If these enzymes are allowed to gather together and randomly cut off the molecular chains of plastic, resulting in incomplete decomposition and the generation of "microplastics" - it is better not to degrade!
Therefore, in the latest study, in order to solve the above problems, the researchers added "individual enzymes" to two biodegradable plastics (including polylactic acid commonly used in food packaging).
They used the enzyme with another biodegradable additive, which ensured that the enzyme neither clumped nor fell apart.
These isolated enzymes grab the ends of plastic molecular chains and cut off each link like chewing pasta. They break down the plastic while preventing the formation of microplastics.
Generally speaking, adding enzymes to plastics increases costs while also compromising the material's properties.
However, the new enzyme only accounts for 0.02% of the weight of the plastic, and the modified plastic is as strong and flexible as the plastic of common shopping bags.
This technology is not yet suitable for all plastics because their molecular structures are different. The R&D team is working hard to overcome this limitation and has also filed a patent application for this technology.
One of the R&D members founded a start-up company to commercialize the patent.