Biodegradable plastics have always been considered to help solve the problem of plastic pollution, but today, most compostable plastic bags are mainly made of polylactic acid, which does not decompose during the composting process and can also pollute other biodegradable utensils recyclable plastics. However, according to the latest research on the 21st, American scientists invented a new technology: only heat and water can make these compostable plastics easier to decompose.
Previously, the research team was able to discover enzymes that are biodegradable and toxic organophosphorus chemical reaction substances, and also designed a molecule we call random heteropolymers or RHP. These intellectuals envelop the enzyme and can be used without restriction. Under the circumstances of natural economic resilience, the enzyme gently combines its development to live together, protecting the enzyme from disintegration. RHP is composed of 4 types of monomer subunits, each of which has chemical engineering properties that promote interaction with chemical structural groups on the surface of specific enzymes. They degrade under ultraviolet light and exist in concentrations less than 1% by weight of the plastic product.
In this study, the research team used a similar technology to make plastics by wrapping 1 billion nanometer-scale edible polyester enzymes in rhp and embedding them in plastic resin beads.
Studies have found that RHP coating enzyme does not change the properties of plastics. When exposed to heat and water, this enzyme removes the polymer coating material and breaks down the plastic polymer. Plastic can melt at about 170 degrees Celsius and squeeze fibers like ordinary polyester plastic. As far as PLA is concerned, enzymes can reduce it to lactic acid, which can "feed" the soil microorganisms in the compost. Polymer coating materials can also degrade.
For PLA, the researchers used such an enzyme called proteinase K, which can chew PLA into lactic acid through molecules; for polycaprolactone (PCL), different lipases are used. These two enzymes are cheap and easy to obtain.
To trigger the degradation of Chinese plastics, just add water and a small amount of heat to pass through. At room temperature, 80% of the modified PLA fiber can be completely degraded within a week. The higher the temperature, the faster the degradation treatment speed develops. Under the conditions of industrial design composting technology, the modified polylactic acid will degrade within 6 days at 50 degrees Celsius. PCL, another polyester plastic, degrades within two days under industrially controlled composting conditions at 40 degrees Celsius.
98% of the plastic produced in this process will be degraded into small molecules. This process avoids the production of plastic particles.
The researchers said that this modified polyester will not degrade under low temperature or temporary humidity. Soaking in warm water can be degraded, which means that plastic can be composted at home.