Banyat Cherdchim, Nirundorn Matan, and Buhnnum Kyokong

pp. 855 - 866

Abstract

The aim of this research is to study the effect of temperature on thermal softening behavior of black
sweet-bamboo culms in linseed oil. Pressing test rig with a length scale and a pointer indicating specimen
height was constructed. This apparatus was used to apply a compressive force to bamboo specimen immersed
in hot linseed oil in a boiler. Half circular cross-section specimens with thickness of 3 mm and length of 150
mm were dipped into water at room temperature to attain water saturated condition prior to immersing into
linseed oil at various temperatures under the load of 20 N. Specimen height, used to calculate the degree of
flatness, was measured as a function of time. The values of the final degree of flatness and the rate of degree
of flatness were used for the analysis of thermal softening behavior of bamboo in linseed oil. It was found
that thermal softening behavior of bamboo culms in linseed oil was divided into two temperature regimes
with the glass transition temperature at 115ºC. At low temperature regime, deformation occurred slowly
and showed only a single stage of deformation, corresponding to deformation in the glassy state. At high
temperature regime, specimens deformed slowly in the first stage followed by a rapid deformation in the second stage, corresponding to deformations in the glassy and rubbery states, respectively. Effect of temperature on the rate of softening was well described by means of the Arrhenius equation with the activation
energy ranging from 18 kJ/mole to 32 kJ/mole.