Quasi-static and dynamic nanoindentation to determine the influence of thermal treatment on the mechanical properties of bamboo cell walls

Abstract Bamboo was thermally treated at 180°C and 200°C, and the micromechanical properties of its cell walls were investigated by means of quasi-static and dynamic nanoindentation experiments. With increasing treatment temperatures, the average dry density and mass of the bamboo decreased, whereas the already reduced elastic modulus at 180°C of the fiber cell walls did not change, but the hardness showed increasing tendencies. Dynamic nanoindentation revealed reduced storage modulus ( E ′ r ) $({E'_{\rm{r}}})$ and loss modulus ( E ″ r ) $({E''_{\rm{r}}}\,)$ for the thermotreated bamboo cell walls compared with the untreated bamboo fibers in all frequency regions. Moreover, E ′ r , E ″ r , ${E'_{\rm{r}}},{\rm{ }}{E''_{\rm{r}}},$ and loss tangent (tan δ) of treated bamboo decreased with increasing treatment temperature.