Integral sandwich structure made of thermoplastic polymer foams


Within the scope of LuFo-project SOPHIA – Smart Processes and Optimized Designs for High Production Cadences (funding reference 20X1715D) - researchers at Leibniz-Institut für Verbundwerkstoffe in Kaiserslautern investigate innovative concepts for the treatment of thermoplastic polymer foams to enable the application in passenger transport aircraft cabins. Currently, the creation of integral sandwich structures, based on inherent flame retardant polyethersulfone (PES) and polyetherimide (PEI) foams is scrutinized. Characteristic properties of polymer foams are low densities and low thermal conductivity, but also low mechanical properties. To increase the mechanical properties of polymer foam parts, integral sandwich structures can be created. For this purpose, polymer foams can be treated in an isochorous hot press process, in which the foam is compacted and the contact zone between foam and tool is heated above glass transition temperature of the polymer. After the material is cooled down, the foam surface becomes a polymer skin with increased density compared to the foam core. To prevent a collapse of the core material only one tool is heated and the foam is treated in two sequential processes to create polymer skins on both surfaces. In comparison to the raw material, this process makes the increase of bending properties as well as impact strength possible without increasing the component weight. Thus, lightweight potential of thermoplastic polymer foams can be enhanced. The adaption of this process into to a continuous compression molding process enables the efficient manufacturing of these structural foam sandwiches with high weight-specific mechanical properties. In a final step, parts can be produced in short cycles by thermoforming processes.

Project partners / partners:

  • Diehl Aviation GmbH
  • Fraunhofer-Institut für Bauphysik
  • Institut für Flugzeugbau, Universität Stuttgart
  • Neue Materialien Bayreuth GmbH
  • Amphenol-Air LB GmbH

On the basis of a decision by the German Bundestag, project “SOPHIA – Smart processes and optimized designs for high productions cadences" is funded by the Federal Ministry of Economic Affairs and Energy (BMWi) within the scope of the aeronautical research programme V-3 (funding reference 20X1715D).

Further informationen:

Dipl.-Ing. Maximilian Salmins
Leibniz-Institut für Verbundwerkstoffe GmbH Press- & Fügetechnologien
Erwin-Schrödinger-Straße 58
67663 Kaiserslautern
Telephone: +49 631 2017-340

Figure 1: Continuous compression molding machine for manufacturing thermoplastic semi-finished products

Figure 2: Micrograph of a polymer foam with skin in light microscope

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