Many of natural structural materials possess very interesting mechanical properties for technical applications. For this reason the structure of these materials has been investigated during the last decades very well. It turned out the natural materials exhibit a hierarchical structure and have a high filling degree of minerals (ceramic). The other components of the natural materials are bio-polymers. Despite a very high filling degree the natural materials possess unexpected high fracture toughness. A typical example of such a damage tolerant natural material is nacre. Nacre consists of about 95 vol.% calcium carbonate and about 5 vol.% of polymeric material.Due of good mechanical properties of natural materials many attempts are made to reconstruct this complex hierarchical structural design.
Main aim of the project is the fabrication of tailor-made high-filled and hierarchical composite materials for different applications. For this aim novel processing routes based on fluidization of particles are developed and optimized and the mechanical properties of produced highly filled ceramic-polymer and metal-polymer composites are investigated. Furthermore the influence of the shape of reinforcement particles is investigated.
The process route for the fabrication of composites with high volume fraction of the reinforcement phase and hierarchical structure is the spouted bed coating process combined with subsequent warm pressing. A miniaturized spouted bed with an annular fluidization gab was designed for the fluidization and coating of very fine particles. Fig. 1 shows the miniaturized spouted bed which enables the fluidization of small amounts of fine particles and as well the usage of organic solvents for the polymer solution due to the operation under the fume hood. With this method it was possible to fabricate both very highly filled composites from hematite particles and SBC-polymer (polystyrene butadiene block copolymer).
After the granulation in the spouted bed the granules are pressed to tablets. After pressing tablets are sawed in bending bars. Afterwards the mechanical properties such as modulus of elasticity and bending strength of the fabricated composites are tested. The polymer content is determined thermogravimetrically and both the coating quality and the composite structure are analysed by SEM. Fig. 2 shows an SEM-image of a FIB-cutted polymer-coated hematite particle.
For the optimisation of the process, fluid and particle dynamics in the apparatus are simulated with CFD (Computational Fluid dynamics)-DEM (Discrete Element Method)-Coupling. For optimization of mechanical properties DEM-simulation are carried out.
- Rothberg, H.S., Pietsch, S., Schneider, G.A., Heinrich, S.: Fabrication of Highly Filled Composites with an Innovative Miniaturized Spouted Bed, Processes, 2020, 8(5), 521, DOI: 10.3390/pr8050521
- Eichner E., Fischer, P.-K., Heinrich, S., Schneider, G.A.: Production of composites with high relative permittivity using the spouted bed technique, Particuology, 42 (2019), 184-189.
- Eichner E., Heinrich, S., Schneider, G.A.: Influence of particle shape and size on mechanical properties in copper-polymer composites, Powder Technol. 339 (2018), 39-45.
- Eichner E., Salikov V., Bassen P., Heinrich S., Schneider G.A.: Using dilute spouting for fabrication of highly filled metal-polymer composite materials, Powder Technol. 316 (2017) 426–433.
- Georgopanos P., Eichner E., Filiz V., Handge U.A., Schneider G.A., Heinrich S., Abetz V.: Improvement of mechanical properties by a polydopamine interface in highly filled hierarchical composites of titanium dioxide particles and poly(vinyl butyral), Compos. Sci. Technol. 146 (2017) 73-82.
- Wolff M.F.H., Salikov V., Antonyuk S., Heinrich S., Schneider G.A. (2014): Novel, highly-filled ceramic–polymer composites synthesized by a spouted bed spray granulation process, Composit. Sci.&Techn. 90
- Wolff M.F.H., Salikov V., Antonyuk S., Heinrich S., Schneider G.A. (2013): Three-dimensional discrete element modeling of micromechanical bending tests of ceramic–polymer composite materials, Powder Techn. 248.
• Institute of Advanced Ceramics, Hamburg University of Technology (Prof. G.A. Schneider)
• Institute of Polymer Research, Helmholtz-Zentrum Geestacht (Prof. V. Abetz)
• Institute of Physical Chemistry, University of Hamburg (Prof. H. Weller)