Characteristics of bamboo tissue in relation to cooling set
2009
Nakajima, M.(Kyoto Prefectural Univ. (Japan)) | Furuta, Y. | Ishimaru, Y. | Ohkoshi, M.
To clarify the effects of tissue and structure of bamboo on its bending properties and set by cooling (bent at 90degC and cooled to 20degC with bending), the effects of set in bast-fiber-rich (Bsub(fib)) and parenchyma-cell-rich (Bsub(par)) specimens were investigated with regard to their dynamic viscoelastic properties, chemical composition, and recovery from deformation with time. The results are summarized as follows: (1) while no clear effect of the proportion of parenchyma cells and bast fibers on residual set immediately after cooling was found, the relative recovery from the deformation with time for Bsub(fib) was larger than that for Bsub(par). (2) Slightly higher lignin content and alpha-cellulose were seen in Bsub(fib) than in Bsub(par). (3) The peak temperature of loss modulus (E'') found for Bsub(par), which was attributable to micro-Brownian motion of lignin, was obviously lower than that for Bsub(fib). This was considered to be due to differences in the degree of condensation of lignin or higher-order structure. From these results, it was deduced that the bast-fiber-rich specimen, which showed a higher peak temperature regarding thermal softening of lignin allowing the induction of insufficient thermal-softening in the range of 20deg to 90degC, caused a larger recovery from deformation with time.
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