【作者】 高景然；

【导师】 邱坚； 郭梦麟；

【作者基本信息】 西南林学院 ， 木材科学与技术， 2009， 硕士

【摘要】 气凝胶是一种优良的绝缘材料,但高度的松脆性和易碎性限制了其使用范围。木材是一种多孔性的绝缘材料。增大木材细胞壁孔隙率,可以在增大木材绝缘性的同时并在一定程度上保持其机械强度。本研究的目的包括:(1)研究轻木、八宝树、吴茱萸、山黄麻、木棉和刺桐的解剖学构造和基本物理性质;(2)处理山黄麻木材试样,使其木材细胞壁膨化;(3)用超临界CO2流体干燥膨化后的木材试样,来保持已在木材细胞壁中形成的孔隙结构。本论文介绍了6种选定木材的基本物理性质,如密度、孔隙率、细胞壁厚度、细胞腔径,以及解剖特性。在膨化试验中,首先分别用5%、10%、15%的硝酸溶液在40 oC、70 oC、100 oC和20min、40min、60min的水平下,采用正交实验处理山黄麻木材试样,然后分别用尿素饱和溶液和氯化锌饱和溶液浸泡膨化处理。试验结果表明:采用10%的硝酸溶液在100oC,20min的条件下处理的山黄麻木材试材,尿素饱和溶液和氯化锌饱和溶液对木材细胞壁的润涨率分别可达77.53%和76.14%。超临界CO2流体干燥的最佳工艺条件为60 oC、12Mp、3h,基本可以保持木材尺寸的稳定性。用扫描电镜观察膨化处理过的试样,结果表明,S3层的微纤丝已经被破坏,S2层明显向细胞腔内膨胀。更多还原

【Abstract】 Aerogel is an excellent insultion material but its application is limited by lacking strength. Since wood is porous and thus it also is a good insulative material. Increasing the porosity of the cell wall not only enhances the insulative properties of wood but also maintains certain level of its mechanical properties.The objectives of this study were to: (1) study the anatomical properties of Ocharoma pyramidale, Duabanga grandiglora, Eoudia rutaecarpa, Trema orientalis, Gossampinus malabaricus and Erythrina arborescens; (2) treat Trema orientalis samples to swell the cell wall beyond to swelling power of water; (3) use super critical CO2 fluid to dry the swollen samples to obtain porous structure in the cell wall.This thesis reported the basic physical properties of the six selected species such as density, porosity, cell wall thickness and cell diameter. In the swelling study, Trema orientalis wood samples were first treated with 5%, 10% and 15% nitiric acid aqueous solution at 40 oC, 70 oC and 100 oC for 20, 40 and 60 minutes, followed by treating the samples with the saturated urea and ZnCl2 solution. Results indicated that treating Trema orientalis with 10% nitric acid at 100 oC and with urea and ZnCl2 saturated solutions caused the fiber tracheid walls to swell 77.53% and 76.14%, respectively. Critical point drying of the swollen samples with super critical CO2 at 60 oC and 12Mp for 3 hours caused little shrinkage of the swollen wood samples. SEM examinations of the nitric acid-treated samples showed that mirofibrils in the S3 layer were severely damaged which caused the S2 layer to swell inward during the subsequent treatments with urea and ZnCl2 saturated solutions.更多还原