Flexible combination: hard and soft at the same time

Instead of welding, riveting or using screws, the components are now preferably bonded in order to connect the components to one another. This makes cars, airplanes and agricultural machines lighter. However, the requirements for adhesives are high: they must be flexible enough to compensate for stress spikes in the bonding area while still providing a rigid connection at the surface. Fraunhofer researchers have now developed the “MetAK” adhesive that is both hard and soft.

Roland Klein, Ph.D., co-developer of the Fraunhofer Institute for Durability and System Reliability at Fraunhofer, explains: “MetAK is comparable to the common two-component adhesives in hardware stores with only more of the components being mixed together. The production is simple because the components do not need to be carefully synthesized in the laboratory; they are commercially available. “The exact formula is our secret,” Klein said.

Hardness can be adjusted separately

The stiffness of the initial viscous material based on synthetic resin can be determined by two hardening mechanisms: UV irradiation and heat. “Areas that should be kept flexible are not irradiated, but rather heat treated to cure them, preferably in conjunction with the radiating areas to form a network whose consistency is rubbery – ideal for dynamic loading, as occurs in a car In this case, the joint zone is particularly exposed to high stress spikes and vibrations – even problems that must be faced by the construction of bonded aircraft parts, wind turbines or trains.

“The beauty of MetAK is that it’s very rigid and easy to adjust, eliminating the need for many different adhesives with different hardness levels, giving you the flexibility to adjust and compensate for the frequency range of vibration. The longer and more intense the UV light, the harder the material. After the final heat treatment with the radiant heater, or in an oven of 100 to 180 degrees (depending on the application) MetAK no longer deforms and the chemical reaction is complete.

Ideal plastic surgery applications

Not only can MetAK be used as an adhesive, it can also be cast into a specific shape. Radiation and heat can then be used to create hard-to-soft regions of flow transitions – for example, attractive for orthopedic applications. Tim Bastian Klaus, a Klein colleague, is working on a Metak cheap wholesale corsets that supports the spine in patients with deformity scoliosis in the right spot, but with the flexibility to yield In other parts. This will help to avoid painful stress points and increase wearing comfort. In addition, MetAK can produce personalized, modernly designed bras and has a permeable structure – important criteria for determining the frequency of wear and therefore the success of the treatment for patients, primarily adolescents. Together with design student Anja Lietzau, Claus won the 2017 Fraunhofer Creative Competition for his thoughts. Klaus said: “This material can also be used for other plastic surgery applications, such as orthopedic shoes or prosthetics.

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