Lightweight and stable – The Nano Argovia project “NanoTough” is investigating new methods for improving the toughness of composite materialsJuly 2018
In the Nano Argovia project “NanoTough”, scientists from the University of Applied Sciences and Arts Northwestern Switzerland (FHNW), the University of Basel, and the company Huntsman Advanced Materials GmbH (Basel) are investigating the use of block copolymers in composite materials. The aim is to make composites tougher without impairing their workability.
Room for improvement
Plastics that have been reinforced with carbon fibers (fiber-reinforced composites) stand out for their combination of extraordinary mechanical properties and low weight. They are primarily used for building vehicles, aircraft, and ships but also play an increasingly important role in the manufacturing of wind turbines. Their range of applications could be expanded further if the materials were less brittle and if their toughness could be improved. This can already be achieved today by adding thermoplastic powders, but the use of such additives increases the materials’ viscosity and therefore makes them harder to work.
Block copolymers as an additive
The teams of scientists working on the Nano Argovia project “NanoTough” begin by investigating the synthesis of various block copolymers, which they later add to an epoxy resin that acts as a matrix. Block copolymers are polymers assembled from at least two different monomers, with single molecules of the monomers linking up in long chains to form the individual blocks (e.g. AAAAABBBBB). The group led by Professor Wolfgang Meier from the Department of Chemistry first synthesizes a variety of block copolymers (BCPs) with different compositions and masses and then studies how these affect the morphology of the resulting nanostructures.
In addition, the researchers attempt to simulate the conditions found in an epoxy resin system by selecting different solvents and temperatures. Once the BCPs are synthesized and characterized, suitable candidates are selected and then tested in an epoxy resin system by the team working under project leader Dr. Sonja Neuhaus and Professor Clemens Dransfeld (FHNW School of Engineering, Windisch). Key factors include not only the conditions during curing but also the morphology of the block copolymers in fully cured samples. A thermoplastic material is then added, and the morphological characteristics of the new composite material are analyzed.
Lastly, partner company Huntsman works with the FHNW team to characterize the samples’ mechanical properties and compare them with leading commercially available materials. This work centers around experiments to test the fracture properties and the determination of the glass transition temperature under a variety of conditions.