Technology Offers Materials Science & Engineering



Bio-based, non-isocyanate shape memory polyhydroxyurethanes (SMPHUs) with programmable and switchable shapes

As part of a project funded by the Baden-Wuerttemberg Stiftung gGmbH, scientists at the University of Freiburg succeeded in developing an innovative, relatively simple process that enables sustainable, less dangerous and preferably solvent-free production of smart poly(beta-hydroxy)urethanes (PHUs) using bio-based components.
These shape memory polyhydroxyurethanes (SMPHU) can be used for a wide range of applications – from moldings, coatings and fibers to films, actuators and components used in medical engineering.

 

 

Quat primer polymers – the universal key to permanent surface functionalization

"Q-primers" are ammonium compounds, which make it possible to permanently functionalize virtually any surface. It is an environmentally friendly and cost-effective process that allows the production of ultra-thin layers and an "on demand" functionalization. The carrier quat primer can be equipped with any functional groups so that an universally applicable strategy for the modification of surfaces is now available.

 

 

Novel carbonization process of PAN-nanofiber mats with enhanced surface area and porosity

This innovative carbonization process of carbon precursor fibers creates in a fast and energy saving manner carbon fibers (CF) which are highly porous (small pore diameters from 0.1 to 10 nm) and have a high surface area (100 to 2500 m2/g). The pyrolysis step needs only minutes or even seconds.

No additional additives like pore-providing templates, catalytic compounds or corrosive liquids are required. However, filler materials like pigments, dyes, graphene nanoplatelets or metal- and semiconductor nanoparticles can be admixed to vary the performance of the produced carbon fibers, e.g. to increase electrical conductivity. Overall, this technology combines conventional carbonization and activation treatments into one process and is more economical by saving time, costs and resources compared to already known thermal carbonization methods.

Applications of carbon fibers are known in the art. Electric applications like super caps and electrodes or filtration and adsorption for gas, water and solvent purification might be preferable.

 

 

Highly conductive pastes for printable electronic applications and devices

At the Karlsruhe Institute of Technology (KIT), a new platform concept for the formulation of highly conductive, printable pastes has been developed. Corresponding pastes are free of polymeric or other non-volatile stabilizers and rheology control agents. Nevertheless, rheological properties like low-shear viscosity and yield stress can be adjusted in a wide range. Thus sedimentation /aggregation is prohibited and long-term stability can be guaranteed even for suspensions of high density particles (e.g. Ag, Ni). Also full control of the application behavior in many different printing/coating operations is furnished.

 

 

Thin layer of air between ship's hull and water prevents biological growth and reduces friction

Within a project of the Baden-Württemberg Stiftung a novel surface technology has been developed that can hold gas molecules between a surface and surrounding liquids. Such a material could be extremely useful in shipbuilding rendering toxic anti-fouling coatings obsolete and simultanously reducing frictional resistance between vessel and seawater, thus saving fuel.

 

 

High-density fibreboard made of renewable raw materials, suitable for free-form modelling

Scientists from Stuttgart University developed a flexible high-density fibreboard with slip-resistant and shock-absorbent properties. The fibreboard consists of 80 % to 90 % straw, a natural, annually renewable fibre and agricultural by-product. It can be produced free of formaldehyde and isocycanate, making it the ideal solution for various indoor applications and minimizing the health risks during the product's entire life cycle. In addition to being recyclable and compostable the new fibreboard is highly flexible and therefore suitable for designing free-form furniture and interior spaces.

 

 

Force constant adaptation of braided sleeving in the automated production of braided components

The Institute of Aircraft Design (IFB) at the University of Stuttgart developed a flexible pressure roll mechanism for braiding machines, which significantly improves the automated braiding of components with sharp curvatures and widely varying cross-sections without the need for manual intervention. While overbraiding a mandrel the flexible mounting of the pressure rolls allows for adaptation to the mandrel's positioning (e.g. inclined position) and to changes in the cross section. They exert a constant and precisely defined force on the braid and thereby press it against the mandrel.
As part of the automated process, the robot control of the braiding machine coordinates the movement of the pressure rolls. This significantly improves the braiding of components with a variable cross-section and curvatures so that manual intervention is no longer required.

 

 

Variable number of threads in braiding machines

A new embodiment of a braiding machine was developed at the Institute of Aircraft Design (IFB) of Stuttgart University. It features a thread positioning unit which forms a secondary ring of horn-gears close to the braiding point. This secondary ring moves synchronously with the primary horn-gears of the braiding machine. Therefore, the position of each thread, that is close to the mandrel, is clearly defined. This is a basic requirement for manipulation of specific threads during the braiding process, which in turn permits the automated production of components with highly varying diameters at a constant braid angle.