Innovative Materialsysteme für 3D-Druck – Uni Freiburg

Innovative Materialsysteme für 3D-Druck – Uni Freiburg


At the Materials Research Center of the University of
Freiburg, young interdisciplinary researchers work on new material
systems and 3D printing techniques. The Freiburg 3D Printing Alliance in which numerous other research institutions and industrial companies are involved is shaping the future of additive manufacturing here. At the Freiburg Materials Research Center (FMF), we conduct interdisciplinary research on new 3D printing techniques as well as
new material systems for 3D printing. I am also personally involved in this research and my work focuses on sustainable and self-reinforcing
polymers which can be used for 3D printing. To strengthen plastic components mechanically, it is common to add glass or carbon fibers. However, the addition of such alien fibers results in the component becoming considerably heavier. Moreover, simple and efficient recycling is often
impossible. A sustainable alternative to these traditional composite
materials is the use of so-called self-reinforcing polymers. Self-reinforcement means that the plastic and the
reinforcing phase are made of the same material and there is no need to add further substances. This is of interest for lightweight engineering on the one
hand and furthermore it is possible to reuse this material, it
can be recycled. The unique feature of the material developed in Freiburg is the formation of fiber-like structures during processing in
the polymer melt, which greatly simplifies production and processing. The material is designed in such a way that it can be processed using all classical methods, including injection molding and extrusion. It can even be used in extrusion-based 3D printing, i.e. in the so-called FFF process. Key component is a special polyethylene developed here in Freiburg with parts of extremely
long-chain molecules, so-called ultra-high molecular weight polyethylene. These ultra-long polymer chains are stretched and aligned along the printing direction as if they were fibers. This leads to exceptional mechanical properties, such as massively improved stiffness, tensile strength, impact strength and also significantly improved abrasion resistance compared to conventional polyethylene. By combining these materials with 3D printing, completely new possibilities in terms of production occur. Thanks to process design, the alignment and thus the reinforcement can be tailored to the stresses acting on a component. Take gears, for example. By 3D printing with our materials self-reinforcement can be generated exactly where it is needed. And that is obviously in the area of the teeth. And this concept can, of course, be transferred to
components of any complexity with very special requirement profiles. Combining self-reinforcing polymers on the one hand with the versatility of 3D printing on the
other, new production possibilities and applications are created
for a sustainable future. Speaking of sustainability in 3D printing. In my doctoral thesis, I use light-based 3D printing
processes combined with biobased, renewable raw materials that you
wouldn’t think of at first. Like orange peels, for example. The advantage of orange peels is that in orange juice production thousands of tons per year
are obtained as a waste product anyway. This means that we can use this biomass very sustainably, as we do not compete with food production. At our institute we can now take the extract of orange peels and convert them into photocurable resins in a simple and
one-step synthesis. The advantage of this synthesis is that, in terms of green chemistry, we do not have to use any
harmful solvents. Afterwards we use these resins in stereolithographic 3D
printing with ultraviolet or blue light. By the very exact and selective lighting we can harden the material where it is required. And the best part is, with the established synthesis and processing we can use almost any natural raw material. Which means depending on the structure of the resource we can tailor material properties. The material properties of our 3D printed objects from the
orange peels are in no way inferior to the commercially known components
based on bisphenol A. On the contrary, we even have compounds that are much less viscous and therefore easier and faster
to print. In addition, our resins do not contain the health-hazardous
bisphenols, which are nevertheless used, for example, in our daily life
in dental medicine. The combination of non-toxic components and high-precision
3D printing is of great interest for biomedical applications. 3D printing is currently revolutionizing medical technology. Tailor-made implants such as artificial hip joints or organs
from 3D printers are no longer a vision but reality. We at the Freiburg Materials Research Center are a part of
this development. One of our research areas is the use of polymer materials in combination with 3D printing for bone and tissue
regeneration. The polymers are used as scaffold structures for bone
regeneration. These structures are fabricated by a special method, known
as 3D dispensing. 3D Dispensing is a printing method that can be used to easily and precisely process highly viscous pastes from
polymer solutions into specific and individual components. The paste we use consists of a carbohydrate-like polymer which chemical structure resembles sugar molecules and is
considered to be particularly biocompatible. Until now it was not possible to process this paste with
conventional methods. In combination with 3D dispensing we have succeeded in producing a material that is highly porous. This high porosity is one of the most essential properties when it comes to reproducing a bone. Large pores ensure a proper transport of the body’s own
cells through the material and small pores provide a high surface area and anchor
points for these cells. The material itself, with its chemical and enzymatic inertness as well as its biocompatibility and structural analogy to
sugar, is considered a perfect material for bone regeneration. This synergy of novel polymer materials and 3D printing has made it possible to produce such customized materials. Thank you very much for your interest. For further information please contact us.

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