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Scientists Create World's 1st Truly Biodegradable Plastic That Can Completely Break Down Under Heat And Water

Scientists Create World's 1st Truly Biodegradable Plastic That Can Completely Break Down Under Heat And Water

Plastic pollution has contaminated the entire planet, from the Arctic to the deepest oceans, and microplastic particles are now known to be consumed and breathed by humans. Because it is currently tough to break down plastic bottles into their chemical constituents to make new ones from old, more new plastic is created from oil each year.

Every year, the world produces more than 380 million tonnes of plastic, which could end up as pollutants in our natural environment and oceans; this figure is expected to double by 2034. Fifty percent of this is single-use plastic, and only 9 percent has ever been recycled.

Biodegradable plastics have been promoted as one solution to the world's plastic pollution problem. Still, today's "compostable" plastic bags, utensils, and cup lids do not break down during standard composting and contaminate other recyclable plastics, causing problems for recyclers. Most compostable plastics, which are primarily made of polyester polylactic acid, or PLA, end up in landfills and have the same lifespan as forever plastics.

Recently, researchers at the University of California, Berkeley, and the University of Massachusetts Amherst developed a new method, which involves embedding polyester-eating enzymes in the plastic as it is manufactured. These super-enzyme degrades plastic bottles six times faster than before and could be used for recycling within a year or two.

With the addition of polymer-munching enzymes, biodegradable plastic packaging and forks could become truly compostable. The new material contains enzymes that chew the plastic down to non-toxic molecules while leaving no traces of harmful microplastics behind.

During the development of plastic, scientists were able to embed polyester-eating enzymes in a special polymer wrapping. What makes this wrapping unique is that when exposed to heat and water, the enzyme sheds its polymer shroud and begins chomping the plastic polymer into its building blocks; in the case of biodegradable plastics, which are primarily made of the polyester polylactic acid, or PLA, it reduces it to lactic acid, which can feed soil microbes in the compost. The polymer wrapping degrades as well.

Researchers added BC-lipase enzyme into PCL plastic and a proteinase K enzyme into PLA plastic. At 40 °C (104 °F), the PCL degraded completely in two days, while the PLA degraded in six days at 50 °C (122 °F). Instead of producing microplastics, the materials degrade into non-hazardous lactic acid.

The super-enzyme, derived from bacteria that naturally evolved the ability to eat plastic, allows for complete bottle recycling. Scientists believe that combining it with enzymes that break down cotton could allow for recycling mixed-fabric clothing.

According to the researchers, this new type of plastic will remain stable during normal use but will only begin to degrade when exposed to compost soil or hot water. The team discovered that soaking the plastic in water at room temperature for three months did not cause it to degrade – that process is only triggered when the heat is turned up a little.

Enzymes are present in the plastic at a concentration of only 1% by weight. These enzyme nanoparticles are wrapped and embedded in the resin beads that begin the plastic manufacturing process.

The research was published in the journal Nature.

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