Adhesive bonding as an enabler for the green transformation

New challenges for adhesive bonding from the circular economy

Adhesive bonding technology has the potential to meet the new climate neutrality requirements of the “European Green Deal” with technical innovations. Adhesive bonding contributes significantly to the energy efficiency of green technologies such as wind turbines, electric vehicles or green building and provides sustainable solutions for the circular economy. To achieve this, it is necessary to take a holistic view of the life cycles of bonded products.

Adhesive bonding in the circular economy

Adhesive bonding is used in products from almost every industry. The advantage is that it permanently bonds different materials while retaining the material properties of the parts to be joined and allowing for additional functions such as sealing or insulation. At the same time, adhesive bonding is compatible with the circular economy. Unlike a screw connection, an adhesive bond is defined as a “non-detachable” connection. However, like all other joints, it will always need to be separated again for the purpose of repair or in order to recycle the recyclable materials.

Currently, industry is increasingly including the requirement for recyclability in the specifications of its products. Fraunhofer IFAM is rising to this new challenge and is therefore working on innovative adhesive bonding solutions in design, chemistry, manufacturing, and disassembly.

Adhesive bonding for wind energy

Due to the good wind conditions on the high seas, offshore wind turbines represent a central building block in German energy and climate policy. Adhesive bonding technology is already used as an established joining technique for rotor blades. In terms of geometry-adapted adhesive application, concepts need to be developed in this area that will significantly reduce the consumption of adhesives and thus resources in the future. Adhesive bonding technology can also be used profitably in other main components such as the foundation structure.

Adhesive bonding for electromobility

Electromobility is an important element for a climate-neutral world independent of fossil fuels. Thermally conductive pastes and adhesives in particular contribute to the performance and service life of electric vehicles by creating a thermal conduction path between the battery module and the cooling system. However, the materials are heavier, used in larger quantities, and thus have an impact on energy and resource consumption. Fraunhofer IFAM is therefore developing novel lightweight material concepts with improved thermal conductivity, suitable mechanical properties, a price suitable for series production and good processing properties. The reuse and recycling of the high quantities of material will be integrated into the focus of developments in the future.

Adhesive bonding for ecological construction

For building practice conditions, Fraunhofer IFAM is working on the development and practical implementation of adhesives with “controlled longevity,” which allows them to better fulfill the high product safety requirements in the “use” phase of the product life cycle, such as strength and durability, as well as the requirements of the “end-of-life” phase of the product life cycle, which have an impact on the ecological balance sheet — an added bonus.

Debonding and re-use of rare earth magnets

Debonding of external permanent magnets of an electric motor.

The production of electric vehicles is increasing rapidly worldwide, requiring larger quantities of rare earth metals such as neodymium, praseodymium and dysprosium to produce permanent magnets.

These magnets are glued into electric motors. Forecasts assume an undersupply of rare earth metals in the future. This makes recycling or reusing the magnets or the rare earth metals more and more attractive. However, the bonding must be detached again for single-variety separation. One possibility for the single-variety separation of materials is “debonding”. This can be done by special triggers that initiate the debonding process. Such triggers can be mechanical, thermal or chemical in nature. The HANNAe research project experimentally investigated a large number of debonding triggers using standardized test specimens. For the most promising debonding strategies, a fully or partially automated deassembly was designed.