The German Fraunhofer Institute has discovered a method to obtain a flexible and functional biopolyester that can also be produced by SMEs
Almost completely biodegradable, and recyclable with little energy, the biopolyester PLA opens new horizons
After use, the plastic should be broken down into its basic components and then produced again. However, some of the material is lost in the process. For an advanced circular economy, these losses could be offset by non-fossil raw materials, creating a type of PLA biopolyester. This, at least, is the idea around which the Fraunhofer Institute worked, resulting in a biodegradable, recyclable polymer of biological origin.
The approach, which earned a prize at the Potsdam Institute, has made polylactic acid more flexible, improving the sustainability of the material. This is no small feat because the classic PLA already has one of the biggest market potentials. Due to its high rigidity, it is suitable for rigid packaging such as disposable cups. However, this is not the case for flexible packaging such as shopping bags, which, however, represent a significant proportion of waste.
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The Fraunhofer solved the problem with so-called polyethers, polymers containing in the chain several ether groups (such as, for example, epoxy resins). These were directly coupled to the polymer chain to make the material more flexible in the long term.
Polyethers are non-toxic, commercially available and can also be produced from raw materials of biological origin. So far, these plasticisers have been mixed with PLA as additives. However, the plasticizer molecules migrate out of the material over time, making the PLA rigid again. To prevent this migration, the researchers anchored the polyether to the polymer. This is a synthesis of PLA-based block copolymers in which the segment of the polyether chain connects to those of the PLA chain at both ends with covalent bonds.
The result is a new and flexible PLA that does not contain migrating plastics and, unlike LDPE, is at least 80% of organic origin. A percentage, which, according to the institute, can reach 100% with further research. Commercial outcomes are possible, they say from Fraunhofer. Biopolyester can be produced economically and with chemical synthesis feasible even by medium-sized companies. Until now, only large plants had control over the production of PLA. With this method things could change. There is more: chemical recycling could be done with a much lower energy supply than that required for LDPE.
