Using regionally available raw materials, Central Germany is to become a showcase region for green chemistry

Regionally available raw materials are to be turned into plastics that can be used in a variety of ways, thus making Central Germany a showcase region for green chemistry: With this goal in mind, 18 partners have joined forces in the "RUBIO" project, which covers the entire value chain from raw materials to recycling. The Fraunhofer Institute for Microstructure of Materials and Systems IMWS in Halle (Saale) is contributing its expertise in the development of bioplastics and the characterization of polymer materials.

© Fraunhofer IMWS
Microstructure of a biopolymer blend of polybutylene succinate (PBS) and polylactide (PLA, dark particles in the image).
© Fraunhofer IMWS
Schematic representation of the RUBIO value chain.

More than 50 million tons of plastics are processed in the EU each year, and the trend is rising. There is strong demand for approaches to replace the materials commonly used to date with environmentally friendly and climate-neutral plastics that can compete with petrochemical products in terms of their processing and usage properties as well as price. RUBIO aims to bring such bio-based and simultaneously biodegradable plastics to market. These could not only be an important building block for green chemistry, but also reduce plastic waste, including microplastics, and reduce the industry's CO2 emissions.

To this end, an alliance of 18 companies and research institutions has joined forces, which is being funded for three years with a total of around 12 million euros from the German Federal Ministry of Education and Research (BMBF). The participating institutions cover the entire value chain for bio-based, recyclable plastics. They will work together in five fields of competence on solutions for the extraction and breakdown of bio-based regional resources, formulation, processing methods up to the annual double-digit kiloton range, and recycling processes. Fraunhofer IMWS is involved in the subprojects of preparation technologies, processing technologies and recycling technology.

The RUBIO consortium is focusing on polybutylene succinate (PBS). This bioplastic enables a high diversity of variants, brings good processing properties and is thus suitable for a wide range of applications in sustainable products. Last but not least, it is readily available regionally: At the beginning of the RUBIO process are materials containing cellulose and lignocellulose that were previously by-products or not utilized at all, such as wood, grasses, residual materials from the paper industry or even fermentation residues from biogas plants. Carbohydrates are first extracted from these plant-based raw materials using biotechnological digestion processes. These are then converted by fermentation into the starting materials for PBS, namely high-purity succinic acid and bio-based 1,4-butanediol. The PBS polymers are synthesized from these monomers by polycondensation. In addition to these process steps, the RUBIO project also aims to develop suitable processes for compounding and manufacturing processes such as injection molding, as well as suitable recycling processes that can be used to filter PBS-containing materials out of the waste stream and recycle them again.

"One of the big advantages of this idea is that the starting raw materials are readily available plant residues. Thus, there is no competition with food, such as with cane sugar-based bio-plastics. In addition, if we achieve our goals, PBS can be processed using a wide range of processes and comparatively little energy. It should be possible to adjust the desired material properties very precisely for the respective demand," says Dr. Patrick Hirsch, who coordinates the RUBIO project at Fraunhofer IMWS. "We are aiming to halve the CO2 balance of the manufactured products as well as the energy consumption during processing compared to the plastics currently used. The location in central Germany is ideal, because in addition to the know-how, we also find the necessary raw material base and infrastructure here," says Hirsch.

Among other things, the Fraunhofer IMWS will contribute its experience in high-resolution structure elucidation and numerical simulation for the formulation and process development of bioplastics. In addition, the morphological, rheological and mechanical processing and use properties will be analyzed here in order to be able to implement efficient development cycles. The institute will also support upscaling with its technical equipment for processing thermoplastics, as well as with its expertise in thermomechanical, oxidative and hydrolytic degradation processes of plastics and the reactive extrusion of recyclates for recycling.

Based on the experience of the project partners, it should become possible to produce high-performance and recyclable plastics for applications such as packaging (films, yogurt pots or shampoo bottles), technical textiles (for example for car construction) and geosynthetics (nonwovens or drainage mats for road construction and civil engineering). PBS also offers good properties in terms of stiffness, strength, elongation at break and impact resistance compared with widely used plastics such as polypropylene (PP) and polyethylene (PE) - and could gradually replace these materials produced from fossil raw materials. It also offers advantages over already available bioplastics such as polylactic acid (PLA), for example in terms of processability and flexibility in use.

After the funding phase, it is planned that RUBIO will enter the market as a leading international consortium for the production and processing of engineering bioplastics. This would also be a contribution to the structural change process with new growth and employment prospects for regional companies in the chemical industry. To this end, the project will also implement its own education and training concept for the required skilled workers.

The Fraunhofer Institute for Microstructure of Materials and Systems IMWS in Halle (Saale) offers microstructure-based diagnostics and technology development for innovative materials, components and systems. Building on its core competencies in high-performance microstructure analytics and microstructure-based material design, the institute researches questions of functionality and application behavior as well as reliability, safety and durability of materials that are used in various market and business fields with high importance for social and economic development. For its partners in industry and for public clients, the Fraunhofer IMWS pursues the goal of contributing to the accelerated development of new materials, increasing material efficiency and cost-effectiveness, and conserving resources. In this way, the institute contributes to securing the innovative capacity of important future fields as well as to sustainability as a central challenge of the 21st century.