高温蒸汽软化竹材的力学性能及结构表征

Mechanical properties and structure characterization of bamboo softened by high temperature steam

为增加竹材的塑性以达到更好的软化效果,采用高温蒸汽软化法将竹材在不同软化温度和时间下进行软化处理,以抗弯弹性模量(MOE)作为评价指标对软化效果进行了研究,并借助傅里叶红外光谱(FTIR)和X射线衍射(XRD)对软化后竹材的主要官能团和结晶特性进行了表征和分析。结果表明:竹材的MOE随软化温度的升高而降低,在软化温度为160℃时降低最显著,同未处理材相比降幅达48.5%;MOE随软化时间的增加先降低后升高,在软化时间为6 min时降低最明显,降幅同未处理材相比达45.5%。当软化温度和软化时间分别为160℃和6 min时,竹材的软化效果较好。随着软化温度的升高和时间的延长,竹材半纤维素结构变化最为明显,有利于竹材的软化,竹材纤维素相对结晶度呈先增大后减小的趋势。因此,适宜的软化温度和时间对竹材的软化效果极为重要。

To increase the plasticity of bamboo, the high temperature steam softening methods with different softening temperatures and times were investigated. The bending modulus of elasticity was used as the evaluation index to examine the softening effect of bamboo. The crystalline properties and main functional groups of softening bamboo were character- ized and analyzed using the Fourier transform infrared spectroscopy （FTIR） and X-ray diffraction （XRD）. The results could provide theoretical foundation for further study on bamboo softening mechanism. The results also showed that the modulus of elasticity of bamboo decreased with the increase of softening temperature, and the most significant reduction was appeared at 160℃, which was reduced by 48.5% compared with the untreated bamboo. The elastic modulus de- creased firstly and then increased with the increase of softening time. The most obvious reduction was 6 min, and re- duced by 45.5% compared with the untreated material. When the softening temperature and time reached 160℃ and 6 min, respectively, the bamboo softening effect was better. With the extension of the softening temperature and time, FT- IR examination showed that the most obvious change was the hemicelluloses structure, which benefited the bamboo sof- tening. The examination of XRD showed that the relative crystallinity of cellulose increased firstly and then decreased. In conclusion, the softening temperature and time are very important for the softening of bamboo.