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Breakthrough in Degradable Plastic

Vipin Saini
Vipin Saini
IMAGE CREDIT: CHRISTOPHER ​DELRE,/UC ​BERKELEY

Scientists Develop Biodegradable Plastic That Easily Breaks Down with Just Heat And Water 

Curbing ​plastic ​pollution is ​one of the ​crucial ​environmental ​challenges that ​humanity is ​facing. Over ​the last ​several years, ​more focus has ​been given ​to ​compostable ​and biodegradable ​plastics but ​these require ​specific ​processes to ​break down. ​Researchers ​have now ​announced a new ​approach to ​plastic that ​can almost ​completely ​biodegrade ​under ​conditions that ​can be much ​more easily ​achieved. ​ 

Reporting in Nature, scientists ​have embedded ​special ​molecules in ​plastic made of ​polylactic acid,​ or PLA, and ​polycaprolactone,​ or PCL. These ​are already ​commonly used ​in compostable ​plastic. The ​special ​molecules used ​are enzymes ​that have the ​ability to ​degrade the ​plastic and ​turn it into ​lactic acid (​which can feed ​microbes in the ​soil) when the ​right ​conditions are ​met. 

The enzymes ​are enveloped ​in polymers and ​then placed ​inside the ​plastic fibers. ​They did not ​change the ​fabric of the ​material, which ​can be employed ​as a normal ​polyester ​plastic. The ​magic happens ​when the ​plastic is ​exposed to both ​water and heat. ​ 

Under ​industrial ​composting ​conditions, the ​team's ​special PLA ​degraded within ​six days at ​50°C (​122°F). For ​the PCL, being ​around 40°C ​(104°F) for ​two days was ​enough to do ​the trick. As ​it currently ​stands, this ​method can ​biodegrade up ​to 98 percent ​of the plastic ​into small ​molecules and, ​importantly, ​doesn’t ​leave ​behind ​any microplastics. 

"People are ​now prepared to ​move into ​biodegradable ​polymers for ​single-use ​plastics, but ​if it turns out ​that it creates ​more problems ​than it's ​worth, then the ​policy might ​revert back," ​senior author ​Professor Ting ​Xu said in ​a ​statement. "We are ​basically ​saying that we ​are on the ​right track. We ​can solve this ​continuing ​problem of ​single-use ​plastics not ​being ​biodegradable." ​ 

The team also ​verified that ​the modified ​polyester ​doesn’t ​degrade at low ​temperatures or ​during brief ​periods of ​dampness. That ​means that you ​could have a ​shirt made of ​this material ​and it won'​t be affected ​by washing on a ​cool temperature ​or sweat. They ​actually kept ​some plastic at ​room temperature ​for three ​months without ​degradation. ​ 

Slightly ​warmer water ​did begin the ​process. This ​is not a ​drawback, ​however. It ​means a water-​based compost ​approach for ​domestic ​composts. ​ 

"It turns out ​that composting ​is not ​enough ​– people ​want to compost ​in their home ​without getting ​their hands ​dirty, they ​want to compost ​in water," Xu ​added. "So, ​that is what we ​tried to see. ​We used warm ​tap water. Just ​warm it up to ​the right ​temperature, ​then put it in, ​and we see in a ​few days it ​disappears."

Xu and her ​team are now ​investigating ​applying this ​method to other ​types of ​plastics as ​well as having ​more control on ​the level of ​biodegradability ​so that the ​plastic can ​partly ​biodegrade and ​the rest can be ​recycled into ​new plastic. ​ 

"It is good ​for millennials ​to think about ​this and start ​a conversation ​that will ​change the way ​we interface ​with Earth," Xu ​said. "Look at ​all the wasted ​stuff we throw ​away: clothing, ​shoes, ​electronics ​like cellphones ​and computers. ​We are taking ​things from the ​Earth at a ​faster rate ​than we can ​return them. ​Don't go ​back to Earth ​to mine for ​these materials,​ but mine ​whatever you ​have, and then ​convert it to ​something else."​ 

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