Hi Tech Sustainable Materials
One of ADD's main design research topics
In this program we step beyond the prior-art, we develop a new type of AM processing for nanofibrillar materials and their materials sciences, and allow for new biomimetic strong and lightweight constructs based on nanocellulose, carbon nanotubes, proteins, inorganics, and their hybrids.
This program looks for new possibilities in AM based on nanoscopically structured nanofibrillar/nanotubular materials, aiming for mechanically excellent materials and feasible AM processing. The work is inspired by the structure of silk, which is a protein with a strength of more than 1.2 GPa (approaching that of steel), still being tough, lightweight and biological, due to the complex interplay of nanoscale hard reinforcing and soft toughening structural nanodomains within its structure. Secondly, unlike classic AM processes, silk fiber is spun in an extended (continuous) “stretched” form by “templating” between supports. This suggests to develop a templated process for continuously spun fibrillar materials for AM.
Here we have the ambitious goal to learn from the structure and processing of silk to develop technically relevant AM approaches. The hard and soft domains of silk suggest to construct hybrid fibers, combining different materials. Due to the sustainability and recently developed processes, we will extensively use nanocellulose, which allows renewable high strength fibers. Its gel spinning has recently been introduced that allows fibers of strength of ca. 300 MPa. It is most encouraging that the process has been transferred to AM processing, allowing templated mesh-like nets. We also use carbon nanotubes, that allow even higher strength, so far ca. 1 GPa. To constuct novel types of hybrid fibers of hard reinforcing and soft toughening constituents, these two materials are used as reinforcements. Also surface modified nanoclays are used to promote the strength. The softer domains within the hybrids are made using proteins, mimicking the structures if silk.
An essential part of the project deals chemically modifying the interactions between the components to allow optimized mechanical properties. The materials and new AM processes will be seamlessly combined with the algorithmic design concepts, to generate new design platforms for meodel applications. The work is also supported by VTT’s multiscale modeling approach optimizing interactions between microstructure and performance.