PLA. A common word present in the Circularity scene. But what is it really? Is it as sustainable as is it marketed? Are its material properties adequate enough to replace the common polymers we all know?
PLA is short for PolyLactic Acid. It is made by fermenting sugars- glucose- from plants to make lactic acid. This lactic acid is then converted to polylactide through ring opening polymerization. There you have it! A full fledged polymer, which now can be used for a number of industrial applications.
Well then, what exactly do we need to make it? It’s that simple. Any crop containing a high carbohydrate content would do. That includes corn, sugarcane, cassava, sugar beets…However these do not come without environmental cost, for modern agriculture does not come without environmental impact. That is why it is important to use second generation biomass, which more information can be read about here. More information on the negative impact of modern farming practices can be found here.
PLA can have quite versatile applications. At the moment, they are most commonly used in single use applications such as takeaway boxes, coffee cups, and films. They are also a favorite in 3D printing, which more information on can be found here. However, one of their most promising applications is in medicine, where implants made of biobased materials are more biocompatible in the human body and can degrade safely without providing further complications.
However, many consumers and businesses are mislead by PLA’s alleged biodegradability. PLA is not biodegradable, it is compostable. The difference? PLA breaks down only in specialized industrial facilities, where high temperatures (up to 55 C) and high humidity are needed, as well as microbial cultures. On the other hand, PLA will behave exactly like its fossil counterparts in the landfill, meaning, it’ll stay put.
There comes another issue to be taken into consideration. Although PLA has a good strength, it is brittle and has a low thermal stability. In other words, it won’t do good in a container with piping hot food or flexible applications. So, the solution for many manufactures is to add plasticizers and additives in order to give PLA the properties desired. But that means that its composability is comprised.
In conclusion, although PLA is a promising material, it faces many dilemmas. The greener it is, the less functional it becomes. The more functional it becomes, the less green it is. That is why those of us who will shape the eco-friendly plastics future must be aware that the road is not over. There is still much work to be done with improving biobased materials, which is where people like Maria of Knowsis come in. We help come up with innovative and creative solutions to these pressing problems that face the circular economy movement, such as greenwashing,stagnation, and lack of implementation. Interested? Email us here.
Fun fact: Although PLA is commonly called Polylactic acid, its monomer is lactide, not lactic acid.