MECHANICAL PROPERTIES OF SILICA CELLS IN BAMBOO MEASURED USING IN SITU IMAGING NANOINDENTATION

摘要

An in situ imaging nanoindentation technique was applied to measure the cell wall mechanical properties of silica cells, as well as pure biogenic silica, in Moso bamboo (Plzyllostachys pubescens Mazel). For comparison, the mechanical properties of thick-walled epidermal cells close to these silica cells, as well as bamboo fibers, were also measured. The silica cells were found to have a high cell wall hardness of about 1 GPa, nearly two times that of the values observed for the other two types of cells. Furthermore, we found that biogenic silica had hardness as high as 2.68 GPa. This explains why silica cells have such high hardness. Conversely, bamboo fibers showed the highest values for indentation modulus, nearly two times greater than that of the other two cell types. This implies silica cells and epidermal thick-walled cells had a large microfibrillar angle compared with bamboo fibers. The results of this study imply that silica cells with exceptionally high hardness may be regarded as a model nanocomposite with cell wall polymers reinforced with SiO2 nanoparticles. More research is needed on silica cells because they might provide inspiration for the development of innovative SiO2-wood composite products with both high hardness and low production costs.