Integral sandwich structure made of thermoplastic polymer foams


Within the frame of LuFo-project SOPHIA – Smart Processes and Optimized Designs for High Production Cadences (funding reference 20X1715D) - researchers at Institut für Verbundwerkstoffe in Kaiserslautern investigate innovative concepts for the treatment of thermoplastic polymer foams to enable their 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 being investigated. Characteristic properties of polymer foams are low densities, low thermal conductivity as well as 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 a variothermal hot press process, in which the foam is compacted and the contact zone between foam and tool is heated above the glass transition temperature of the polymer. After the tool has been cooled down, the foam surface becomes a polymer skin with increased density compared to the foam core. To prevent the 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 without increasing the part weight possible. Thus, the lightweight potential of thermoplastic polymer foams can be increased further.

Project partners/partners:

  • Diehl Aviation GmbH
  • Fraunhofer-Institut für Bauphysik
  • Institut für Flugzeugbau, University of Stuttgart
  • Institut für Verbundwerkstoffe GmbH
  • 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 information:


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

Figure 1: Surface of integral sandwich structure and raw material

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

Figure 3: Polymer foam with skin in scanning electron microscope

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