纳米铜热处理竹材制备及其防霉性能

Preparation of heat-treated bamboo with nano-copper and its anti-mold performance

以毛竹为原料,通过将竹材真空浸没于氢氧化铜、聚乙二醇200和二乙醇胺混合溶液中,并在热处理温度为220℃的条件下分别进行4,6和8 h的热处理,借助液相还原原理,在热处理竹材内部生成纳米铜。通过场发射扫描电子显微镜(FE-SEM)、傅里叶变换红外光谱(FT-IR)、X射线衍射仪(XRD)和X射线光电子能谱(XPS)对热处理竹材进行定性和定量表征。SEM和EDS检测显示,铜元素存在于竹材内部,并且含量随热处理时间增加而增多;XRD和XPS测试证实了存在于竹材内部的铜元素由纳米铜颗粒和少量纳米氧化铜组成;FT-IR结果表明,竹材中的半纤维素发生降解,亲水性基团数量明显降低。热处理后竹材的力学性能均有一定程度降低,吸湿性明显下降。然而,纳米铜热处理竹材的静曲强度和弹性模量仍分别能达到92 MPa和8.9 GPa,接触角均高于120°,吸湿率均低于5.0%,明显优于热处理竹材。黑曲霉、绿色木霉和桔青霉的防霉性能测试结果显示,纳米铜热处理竹材基本未发生霉变,3种霉菌的平均感染值在0.1以下,霉变防治效力均高于96%,相对于天然竹材和热处理竹材具有显著的改善,表现出优异的防霉性能。本研究提出的一步法制备纳米铜热处理竹材的思路不仅工艺简单,制品性能优异,还将进一步拓宽竹材的应用领域,促进“以竹代塑”的高效发展。

In this study,moso bamboo was vacuum immersed in a mixed solution of copper hydroxide,polyethylene glycol 200 and diethanolamine,and subjected to heat treatment for 4,6,and 8 h under 220 ℃.According to the principle of liquid-phase reduction,nano-copper was generated inside the heat-treated bamboo.The characterization of heat-treated bamboo was detected using the field emission scanning electron microscope(FE-SEM),Fourier infrared spectroscopy(FT-IR),X-ray diffractometer(XRD),and X-ray photoelectron spectroscopy(XPS).The results indicated that the copper element distributed in the bamboo and the content increased with increasing heat treatment time.XRD and XPS tests confirmed that the copper element was composed of nano-copper particles and a small amount of nano-copper oxide.The FT-IR test indicated that the substantial hemicellulose of bamboo was degraded,which resulted in a significant decrease in the number of hydrophilic groups.After being heat-treated,the mechanical properties of bamboo significantly decreased,while the moisture absorption was greatly reduced.However,the modulus of rupture(MOR) and modulus of elasticity(MOE) of the heat-treated bamboo with nano-copper particles still reached 92 MPa and 8.9 GPa,respectively,which was significantly higher than the heat-treated bamboo.At the same time,the contact angle of the heat-treated bamboo with nano-copper was up to 120°,and the moisture absorption rate was smaller than 5.0%,which was greatly enhanced compared to the heat-treated bamboo.Moreover,the heat-treated bamboo with nano-copper displayed superior anti-mold ability in the growth tests involving Aspergillus niger,Trichoderma viride,and Penicillium citri.The average infection values of all molds were below 0.1,and the anti-mold effects were up to 96%.Compared to natural bamboo and heat-treated bamboo,the anti-mold performance of the heat-treated bamboo with nano-copper was greatly improved.Therefore,the one-step method proposed in this study for preparing heat-treated bamboo with nano-copper was not only simple in process,but also excellent in performance.This will expand the application fields of bamboo and promote the efficient development of bamboo as a substitute for plastic.