Polylactic acid does not emit microplastics into the environment
Polylactic acid, also known as PLA, is a thermoplastic monomer. It comes from renewable organic sources such as corn starch or sugar cane. This means that PLA is different from most plastics. It does not break down into persistent microplastics, but degrades completely in the presence of water (hydrolysis). As more and more microplastics become a persistent problem at the end of their lifespan, this is a promising way out.
These are the findings of Hydra Marine Sciences in a study commissioned by the Dutch Bioplastics Association, which advances knowledge of bioplastics worldwide. Polylactic acid is a biobased polymer made entirely from fermented plant sugars. The study shows that in an aqueous environment, PLA will hydrolyze into molecules of smaller size (hydrolysis).
1. Lactic acid hydrolysis is an abiotic process that occurs in the presence of moisture or humidity. In this case, polylactic acid breaks down into smaller fragments. The rate at which this occurs is determined by the temperature. Eventually, the polymer chains are so short that the material becomes soluble in water. Subsequently, it will be biodegraded by microorganisms into biomass, water and carbon dioxide. In other words: these processes do not produce toxic substances. Lactic acid, the monomer building block of PLA, is classified as safe and non-toxic in both the United States and the European Union. The same applies to the food contact requirements of many PLA grades. In addition, specific grades of polylactic acid have been approved and used for decades in medical applications, such as sutures and tissue scaffolds. These substances are safely absorbed and bio-assimilated by the human body after use. We now use it to make a variety of products: cups, cutlery, trash can liners, flexible food packaging. In other words, PLA seems suitable to overcome at least part of the microplastic problem.
2. Microplastics, an underestimated problem Microplastics pose a problem that is underestimated by the industry. In this regard, consumer sentiment may be far ahead of industrial policy. Anthony Schiavo of Lux Research warned that this could trigger a backlash. He believes that before the backlash really starts, companies need to actively respond to consumer sentiment by identifying and formulating the worst sources of microplastics and directly participating in microplastic cleanup efforts and technologies.
Others agree with this view. Erwin Vink, a board member of Dutch Bioplastics, said that on the one hand, we need to choose more responsible materials for the products we rely on; on the other hand, we need to develop better plastic collection and waste disposal infrastructure. Polylactic acid will be part of the solution because it will not have the long-term effects of the current microplastics and nanoplastics, which are the final stage of non-biodegradable substances. Even so, for PLA, we should avoid littering the environment.
3. Biodegradable plastics Fortunately, there are more biodegradable plastics, such as polylactic acid, polyhydroxyalkanoates (PHA), starch blends, cellulose-based plastics, and lignin-based polymer composites. PLA stands out because it is not only environmentally friendly, but also a cheap and versatile plastic. And it has a low carbon footprint. We produce lactic acid from plant sugars through fermentation, which is then polymerized into polylactic acid biopolymer PLA.
Wikipedia says that polylactic acid, because it is economically produced from renewable resources, has become a popular material. In 2021, PLA is the world's most consumed bioplastic. PLA is the most widely used plastic filament material in 3D printing because it has a low melting point, high strength, low thermal expansion, and good layer adhesion. It has many properties that may make it the most widely used plastic in the world.
