The Mechanism of Improvement of Physical Properties of Moso Bamboo (Phyllostachys pubescens) with Increasing Age III. Investigation from measurement by dimension changes for green bamboo by heating

摘要

The aim of this paper is to make clear the factors related to changes with increasing age of the physical properties of bamboo as a material. We measured the dimensional changes of green moso bamboo (Phyllostachys pubescens) at various ages (43 days 9 years since shooting) during heating. The dimensional changes which appeared in moso bamboo specimens were compared with the various components of the same individual moso bamboo found in our previous researches. The results of measurements in this paper were as follows; the dimensional changes in the tangential direction progressed with increasing age, from 43 days to 105 days since shooting; shrinkage was observed; and to 84 days since shooting, the degree of deformation became larger with increasing age. At 105 days since shooting, the deformation changed to extensional deformation. After that, the degree of deformation became greater with increasing age up to 9 years since shooting. In our past reports, it was found that the ratio of lignin content increased in the period from 43 days to 84 days, and from the results of measurement of the temperature dependencies of the dynamic viscoelastic properties, it was anticipated that the degree of polymerization and/or crosslinking density increased with the maturing process of moso bamboo. Fourier-transform infrared spectroscopy suggested that the distance between the functional group and other functional groups decreases in the period from 84 days to 9 years since shooting. From these results, we proposed a schematic representation indicating the changes in components of moso bamboo with maturing.