Extrusion International 5-2024

54 Extrusion International 5/2024 environment, and, above all, they are not bio-based,” Lieske adds. Material and process development based on PLA The biopolyester PLA is a promising approach to solving this problem: It is bio-based, biodegradable, easily recyclable and has one of the strongest mar - ket potentials when it comes to bioplastics. Due to its high stiffness, it is perfectly suited for rigid packaging such as disposable cups – but not for flexible dispos- able packaging such as shopping bags, which are one of the main sources of disposable plastic waste. Dr. Antje Lieske has solved this problem together with her colleagues André Gomoll and Dr. Benjamín Rodrí - guez at Fraunhofer IAP. “We coupled plasticizers, so-called polyethers, direct - ly with the polymer chain to make the material more flexible over the long term. Polyethers are non-toxic, commercially available and can also be produced from bio-based raw materials. Until now, plasticizers have been mixed into PLA as additives. However, the plasti - cizer molecules migrate out of the material over time, making the PLA stiff and rigid again. To prevent this migration, we anchored the polyether to the polymer. To achieve this, we synthesized PLA-based block copoly - mers in which the polyether chain segment is covalently linked to PLA chain segments at both ends,” explains Dr. Benjamín Rodríguez. Sustainable and flexible plastic with great potential The result is a novel, flexible PLA material that does not contain migrating plasticizers and, unlike LDPE, is at least 80 percent bio-based. “In the long term, we might be able to increase this proportion to almost 100 percent,” Gomoll explains. “In addition, our material can be produced cost-efficiently from commercially available raw materials in a simple synthesis process. This process does not require large-volume synthesis plants but can be implemented locally by medium- sized companies as a continuously operated process. Until now, PLA could only be produced profitably in continuous large-scale plants, which excluded small - er companies as manufacturers. Finally, the new PLA material can also be processed into plastic films using conventional processing equipment in a similar way to LDPE – and it can be chemically recycled with consider- ably less energy input than LDPE,” Gomoll continues. These unique material properties prompted the Polymer-Group company to commercialize the mate - rial. In 2023, SoBiCo GmbH, a subsidiary of the Poly - mer-Group, commissioned a production plant for the new PLA block copolymers in Pferdsfeld (western Ger - many). It produces 2,000 tons of the new bioplastics per year under the name Plactid®. In the long term, it is set to produce 10,000 tons of the new flexible PLA material each year. The new class of bioplastics will make an important contribution to making plastic packaging materials more sustainable. In addition to flexible packaging films, the new material might also tap into completely new use cases, e.g., in the automotive sector, in the textile industry and in additive manufacturing. Joseph von Fraunhofer Prize Since 1978, the Fraunhofer-Gesellschaft has award - ed the annual Joseph von Fraunhofer Prize to its em - ployees for outstanding scientific achievements in de - veloping solutions for practical problems. This year, three prizes, each worth 50,000 euros, will be award - ed to groups of researchers from different institutes. Fraunhofer Institute for Applied Polymer Research IAP Potsdam Science Park, Geiselbergstr. 69, 14476 Potsdam, Germany www.iap.fraunhofer.de BIO-BASED PLASTICS – FROM THE RESEARCH The researchers in their lab: Dr. Antje Lieske, Dr. Ben-jamín Rodríguez and André Gomoll from Fraunhofer IAP (from left to right) The new PLA material can be processed into plastic films in a similar way to LDPE using conventional processing plants (Pictures: © Fraunhofer: Piotr Banczerowski)