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B. Koch, A. Hochwallner, R. Liska, J. Stampfl:
"Ink development for the fabrication of digital materials with increased fracture toughness";
Talk: ESIAM, Online; 09-08-2021 - 09-10-2021.

Most photopolymers which are available for lithography-based additive manufacturing technologies (L-AMTs) yield brittle materials. To increase the field of application for 3D printed parts, a lot of effort is being put into enhancing the mechanical properties of such materials. While most approaches try to modify the material on a molecular level, this work is exploring the possibilities of locally modifying the properties of photocurable resins. This can be conducted by selectively adding a secondary material to the layers of the primary material. The resulting composite can be referred to as digital material, in the sense that the local properties are either modified or unmodified. In this way the combination of different material properties is possible.
The goal of this work is to digitally modify a hard matrix material printed by a lithography-based AMT-printer with a soft ink applied by an Inkjet-printer in order to get structural parts that can withstand a wider range of load cases while retaining the thermo-mechanical properties of the primary material. In this way, a tough material with high heat deflection temperature, elastic modulus and elongation at break should be obtained.
Therefore, suitable inks fulfilling a wide range of requirements have to be developed. The inks were characterized by viscosity, surface tension, RT-FTIR photorheology and DMTA measurements as well as tensile tests to receive information about the jettability, the photoreactivity and the (thermo)mechanical properties. Promising inks were applied to toughen a hard matrix material. The resulted digital materials were analyzed regarding their mechanical properties and the quality of the jetted structures to describe the impact on the fracture toughness originating by the application of different optimized soft inks on a hard matrix material.

photopolymers, lithography-based additive manufacturing technologies (L-AMTs), photocurable resins