The effect of print speed and material aging on the mechanical properties of a self-healing nanocomposite hydrogel

A UV-curable nanoclay-zwitterionic hydrogel is synthesised and evaluated though rheological and mechanical testing. The results show that aging time of the pre-gel has a big impact on storage and loss of modulus which both increases with increasing aging time, particularly in the first 48 h. The pre-gel is successfully printed and is shown to be able to support itself making it possible to fully print structures before curing. Compression and tensile samples are printed and compared to cast samples. The pre-gel aging time showed that an increased time resulted in a lower strain at failure for both cast and extruded samples. However, when printing with a speed of 10 mm/s with UV-curing during printing, a significant increase in strain at failure is achieved. Furthermore, the compressed samples display self-healing abilities at room temperature and almost completely returns to its original state before compression occurred.