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Issue 06/2022

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Highlights: Films / Flexibles / Bags Consumer Electronics Basics: Chemical Recycling K'2022 review

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Films Production of biodegradable packaging from seaweed The company Brabender, together with the TU Dresden (Dresden, Germany) and the University of the Philippines (Quezon City, Philippines), is researching the processing of seaweed into a cost-effective and sustainable plastic alternative. The films and packaging made from seaweed could be used in the future as films for detergent pods or dishwasher tabs, for example. Seaweed as a sustainable solution Plastic pollution in combination with the longevity of mostly fossil-based materials is a well-known issue of modern times. Part of the solution to counteract this issue might lie in naturally occurring seaweed. While many biobased and biodegradable plastics struggle to be sustainable and economically viable alternatives due to high prices, poor processability, or limited availability, seaweed have great advantages. They are available in large quantities at low cost and the seaweed can easily be processed into a polymer material, providing an alternative to conventional plastics. This new material can be used, for example, for environmentally friendly packaging. These sea plants have various advantages: they grow quickly and need neither freshwater nor fertilisers. In addition, there is a huge area of cultivable land in the oceans: “Around 70 % of the earth’s surface is covered with ocean water, so we have a large theoretical area of cultivable land that is currently barely used. In comparison, 20 % of the Earth’s surface is covered with fertile land and is intensively used for, e.g. agriculture, forestry, infrastructure, or nature reserves. There is therefore a lot of potential in seaweed as a renewable raw material to partially replace plastics, which is currently not yet being used”, explains Ludwig Schmidtchen, Application Engineer at Brabender. In addition, the cultivation of seaweed counteracts the eutrophication of the oceans caused by over-fertilisation in agriculture and the acidification of the oceans, and would thus be helping with the protection of the marine ecosystem. Schmidtchen is conducting research on the topic of producing a sustainable alternative to petrochemical plastics from seaweed at Brabender, as part of his PhD thesis at the TU Dresden. The doctorate, at the Institute for Processing Machines/Processing Technology at TU Dresden, is taking place in cooperation with the Marine Science Institute of the University of the Philippines in Quezon City. Processing seaweed on laboratory scale So far, results of the investigations in the fields of characterisation, quality assessment, and processing of the seaweed raw material using various Brabender analytical instruments to develop a suitable quality analysis and process are quite impressive: With the help of the Brabender TwinLab-C 20/40 twin-screw extruder and Univex flat film take-off, Schmidtchen has processed the seaweed into a brownish film. “In its current state, the extruded seaweed film can be used, for example, as a water-soluble casing for detergent pods and dishwasher tabs”, says Schmidtchen. In conventional dishwasher tabs, the cover is made of the water-soluble synthetic polymer polyvinyl alcohol, which is proven and scaled in its processing but is still more costintensive than seaweed. “In the long run, processing seaweed into films is much cheaper than polyvinyl alcohol, because the processing of seaweed requires less energy than polyvinyl alcohol production and is much easier”, Schmidtchen notes. In addition, closed material cycles in the sense of a circular bioeconomy can be achieved with the seaweed material for water-soluble applications, which is hardly possible with any other polymer. Life cycle of seaweed-based material The seaweed material is a natural polymer material that can become economically competitive with conventional thermoplastics. It has similar mechanical properties to currently used packaging materials and can be heat-sealed, as is the case with chips bags or other packaging, for example. The idea is not new The cultivation potential for seaweed is huge and does not compete with food crops. The idea of using seaweed polymers for film production is not new – as early as 1934, there were initial ideas for seaweed film production in Japan. However, this idea did not catch on at the time due to a lack of political and social interest. In addition, there were only insufficient technical solutions for industrial production. Today, things are different. This is made possible by the novel approach of semi-dry extrusion to produce a 100 % seaweed-based packaging material. The semi-dry extrusion of seaweed biomass into various packaging products saves not only water but also energy resources with minimal negative environmental impact. 40 bioplastics MAGAZINE [06/22] Vol. 17

By: By Ludwig Schmidtchen Application Engineer for Biopolymers Films Brabender, Duisburg, Germany Before the seaweed can be processed, it grows in aquacultures, is harvested and dried in the sun. Then the raw material is crushed with the help of a grinder. A quality analysis with the Brabender ViscoQuick is used to characterise the raw material for further processing. “We have developed extra methods for this application. Based on our measurements, we can make statements about the quality and how to use the material”, Schmidtchen summarises. Life cycle of conventional plastic Scaling up of the project is still pending After characterisation, the ground seaweed can be processed in an extruder into pellets for further processing or the film product. The seaweed material can additionally be used in combination with natural plasticisers or natural pigments to adapt the colour and material properties for specific applications. In the processing stage, Brabender contributes its expertise in raw material characterisation and extrusion processing. The entire value chain, from quality control of the seaweed to the finished film or injectionmoulded part, can be covered with Brabender equipment and the respective experts accompany the tests in the application laboratories. The seaweed project proves that the prerequisites for the development of a sustainable, environmentally friendly, feasible, and economical plastic alternative have been created. Now the project could also be implemented on a larger scale, but suitable partners and co-investors are still lacking. “After the implementation works on laboratory scale, the process can now be scaled up to a pilot plant. For this, we are currently looking for investors or partners who are interested in large-scale implementation”, says Schmidtchen. | bioplastics MAGAZINE [06/22] Vol. 17 41

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