户外用重组木的结构演变和防腐机理研究

发布时间：2018-01-15 06:21

本文关键词：户外用重组木的结构演变和防腐机理研究　出处：《中国林业科学研究院》2017年博士论文　论文类型：学位论文

【摘要】：重组木是以速生林木材为主要原料,木束或纤维化木单板为基本构成单元,浸渍胶黏剂后按顺纹组坯压制而成的板(方)材。重组木经过40余年的研究和发展,逐渐成为速生林木材高效利用的主要途径之一。随着木结构建筑、湿地园林景观设施等领域开始大量使用木质复合材料,加之优质硬阔叶材的不断短缺,重组木逐渐被作为户外用材应用于户外领域。由于户外用材必须具有良好的力学性能和耐侯性,目前对于重组木的研究主要集中在工艺和装备上面,而对于重组木的制造成型基础和户外应用研究比较少。因此,本论文针对重组木上述研究的不足,展开了初步的研究和探索。本文以杨木和落叶松为主要对象,研究了纤维化单板的基本单元特性;然后通过密度和浸胶量等工艺因子来制备高性能的户外用重组木,研究了重组木的力学性能、物理性能和表面性能;在此基础上,采用扫描电子显微镜、激光共聚焦显微镜、微型计算机断层扫描仪、纳米压痕仪、透射电子显微镜、傅立叶变换红外光谱仪和X射线衍射仪等先进仪器设备,对重组木的结构演变、胶合界面和防腐机理进行了研究,得出如下结论:(1)户外用重组木的物理力学性能可通过密度和浸胶量等工艺因子的调整,达到户外用材的使用要求。力学性能方面,浸胶量为13.0%,密度为1.15 g/cm3的杨木重组木,其静曲强度达到201.37 MPa,水平剪切强度达到17.99 MPa,比相同浸胶量,密度为0.85g/cm3的重组木增加了38.71%和38.49%。耐水性方面,经过28 h循环水煮试验后,浸胶量为18.0%,密度为1.00 g/cm3的杨木重组木,其吸水厚度膨胀率为23.73%,吸水率为34.15%,比浸胶量为8.0%,相同密度下的重组木分别降低了54.51%和46.13%。(2)从原木疏解成纤维化单板,最后重组成重组木,材料的细胞组织结构发生了一系列演变。从宏观上看,纤维化单板的表面呈现一系列点状和线段状的裂纹,形成纵向不断裂、横向相互交织的纤维网状结构。从微观上看,杨木纤维化单板的大部分导管、木射线和部分纤维细胞被分离破坏,落叶松纤维化单板的部分早材管胞、木射线等细胞被疏解分离。这些独特的细胞组织构成了纤维化木单板的细胞族群。当杨木纤维化单板制作成重组木后,疏解破裂部分的导管基本被压密实,并随着密度的增大,未被疏解破坏的导管、木射线和纤维细胞腔也逐步被压缩,孔隙越来越小。当杨木重组木密度为1.15g/cm3时,导管管孔基本闭合,木纤维细胞腔也被压缩到一定程度,孔径和孔隙率都达到最小值,分别为36.5 nm和17.84%。(3)酚醛树脂胶先进入因疏解而形成的裂隙、破裂的导管、早材管胞和木射线,并填充细胞腔,然后再渗透进入完整的导管、木射线、早材管胞和纤维细胞的胞腔和细胞壁中。当纤维化单板制作成重组木后,酚醛树脂固化交联沉积在细胞腔内部和细胞各壁层中,并在细胞之间形成胶钉连接,将疏解不完整的和被压缩的细胞组织固定。酚醛树脂胶在重组木细胞组织中的分布随着浸胶量的增加而增加。杨木重组木纤维细胞壁的弹性模量比素材提高了10.10%,硬度比素材增加了31.91%。(4)户外用重组木的防腐性能可通过密度、浸胶量和防腐剂等因素的调整和添加,达到户外用材的所需耐腐等级。在白腐菌12周侵蚀下,浸胶量为18.0%,密度为1.00 g/cm3的杨木重组木的质量损失率为23.24%,比浸胶量为8.0%,相同密度下的重组木降低了42.77%,耐腐等级从III级变为II级;浸胶量为13.0%,密度为1.15 g/cm3的质量损失率为12.34%,比相同浸胶量,密度为0.85 g/cm3的重组木降低了61.68%,耐腐等级也从III级变为II级。不论是白腐或褐腐菌侵蚀,经过铜唑防腐剂处理,浸胶量为13.0%,密度为1.00 g/cm3的重组木的质量损失率均小于10%,达到I级强耐腐等级,说明经过防腐剂处理的重组木具有优异的耐腐性能。浸胶量为13.0%,密度为1.00 g/cm3的落叶松重组木在白腐菌腐朽下质量损失率为11.43%,在褐腐菌腐朽下质量损失率为18.42%,均属于II级耐腐等级。(5)经过12周的真菌侵蚀试验后,重组木的综纤维素、α-纤维素和半纤维素减少,酸不溶木质素则随之增加。浸胶量越多、密度越大和经铜唑防腐剂处理的重组木,结晶度越高,化学基团特征峰的强度损失越小,细胞结构的破坏程度也越小。(6)重组木的防腐性能增强机理主要有:(a)细胞的填充和强化。酚醛树脂填充部分木材细胞腔,并与细胞壁部分活性基团反应形成稳定的交联,使木材细胞壁纤丝紧密相连。重组木的浸胶量越多,细胞腔含有的酚醛树脂越多,交联基团也越多,从而有效地提高了重组木的防腐性。(b)细胞的压缩密实化。重组木的致密组织结构使菌丝可侵入空间和路径减少。重组木的密度越高,细胞之间的间隙越少,同时单位体积内的纤维含量和酚醛树脂含量也增多,有效地抑制了腐朽菌的侵蚀。(c)细胞的化学防治。铜唑类防腐剂能很好的进入导管、木射线和纤维的细胞壁中,与细胞壁物质反应生成铜络合物,有效抑制腐朽菌的生长和繁殖,从而提高重组木的防腐性。
[Abstract]:The scrimber is a fast-growing wood as the main raw material, wood beam or fibrosis wood veneer as basic unit, according to the longitudinal adhesive impregnated blank pressed plate (square) material. The reorganization of wood through the research and development of more than 40 years, has gradually become one of the main ways of efficient use of fast-growing wood. With the wooden structure, the wetland landscape facilities and other fields began to use large amounts of wood composite materials, combined with high-quality hardwood continuous shortage of scrimber gradually as outdoor materials used in outdoor areas. The outdoor materials must have good mechanical properties and corrosion resistance, current research on the reorganization of wood mainly in technology and the above equipment, but less on manufacturing base for the reorganization of wood and outdoor applications. Therefore, this thesis for the study of scrimber, carried out a preliminary study and exploration of the Wen Yiyang. Wood and larch as the main object, studied the basic characteristics of single unit fibrosis plate; then the density and quantity of dipping process factor to prepare high performance outdoor with recombinant wood, mechanical properties of the reconstituted wood, physical properties and surface properties; on this basis, using scanning electron microscopy, confocal laser confocal microscope, micro computed tomography, nanoindentation, transmission electron microscopy, Fu Liye transform infrared spectroscopy and X ray diffraction instrument and other advanced equipment, the evolution of structure of scrimber, bonding interface and anticorrosion mechanism was studied, and draws the following conclusions: (1) outdoor physical and mechanical properties, reconstituted wood glue the density and leaching factor adjustment, to require the use of outdoor materials. The mechanical properties, the resin content is 13%, the density of 1.15 g/cm3 of the poplar scrimber, the bending strength reached 20 1.37 MPa, horizontal shear strength reached 17.99 MPa, the resin content ratio is the same, the density increased by 38.71% and 38.49%. water resistance for scrimber 0.85g/cm3, after 28 h cyclic boiling test after dipping the amount of 18%, 1 g/cm3 density of poplar scrimber, the thickness of the water swelling rate was 23.73%. The water absorption rate is 34.15%, than the resin content is 8%, the reorganization of wood under the same density were decreased by 54.51% and 46.13%. (2) from the log discongest into fibrosis veneer, finally the recombinant recombinant wood, has undergone a series of evolution of cell structure materials. From a macro perspective, the crack surface veneer of fibrosis a series of point and line shape, the formation of longitudinal fracture, fiber network structure lateral intertwined. From the microscopic point of view, most of the poplar veneer duct fibrosis, wood ray and part of the fiber cells were isolated from destruction, the early part of Larch veneer fibrosis Wood tracheid and wood ray cells are ease separation. These unique cells constitute fibrosis veneer cell populations. When the poplar veneer made of reconstituted wood fibrosis after rupture part of the catheter is to ease the pressure and density, with the increase of density, ease is not damaged wood catheter. Ray and fiber cell cavity is gradually compressed, pores smaller. When the poplar scrimber density is 1.15g/cm3, the guide pipe hole closed, wood fiber cell cavity is compressed to a certain extent, pore size and porosity have reached the minimum value, respectively 36.5 nm and 17.84%. (3) first into phenolic resin due to the formation of cracks and ease the rupture of the catheter, earlywood tracheid and wood ray cell, and fills the cavity, and then penetrate the complete catheter, wood ray, earlywood tracheid and fibroblast cell and cell wall. When the single board made of reconstituted fibrosis After the curing of phenolic resin deposition in the cell wall and cell layer in the internal cavity, and the formation of gel nail connection between cells, will ease the incomplete and the compressed tissue fixation. Distribution of phenolic resin in reconstituted cells in a tissue with increasing resin content increased with the elastic modulus of Yang. Recombinant wood wood fiber cell wall was 10.10% higher than the hardness of material, an increase of more than 31.91%. material (4) outdoor anticorrosion performance can be reconstituted by density, resin content, preservatives and other factors to adjust and add to the required outdoor materials corrosion grade. In 12 weeks the erosion of the white rot fungus, the resin content is 18%, the mass loss density of 1 g/cm3 poplar scrimber rate was 23.24% and the ratio of resin content is 8%, the reorganization of wood under the same density decreased 42.77%, corrosion grade from grade III to grade II; resin content is 13%, the density of mass loss of 1.15 cm3 g/ The loss rate of 12.34%, than the same amount of glue, density of scrimber 0.85 g/cm3 reduced 61.68%, corrosion grade from III grade to II grade. Both white rot or brown rot erosion after copper azole preservative treatment, dipping amount was 13%, density of 1 g/cm3 mass loss of scrimber the loss rate is less than 10%, reaching I level strong corrosion grade, that after the reorganization of wood preservative treated with excellent corrosion resistance. The resin content is 13%, density of 1 g/cm3 larch wood recombinant in white rot fungi decay under the mass loss rate of 11.43%, the mass loss of brown rot decay under the loss rate is 18.42%, belong to grade II corrosion grade. (5) after 12 weeks of fungal erosion test, recombinant wood holocellulose, alpha cellulose and hemicellulose reduced, acid insoluble lignin was increased. The resin content more, higher density and wood preservatives treated by recombinant the higher the degree of crystallization. The strength loss of the characteristic peaks of the smaller groups, damage the cell structure is smaller. (6) corrosion resistance enhancement mechanism of scrimber are: (a) cell filling and strengthening. Phenolic resin filling part of the wood cell cavity, and cell wall active groups cross-linking reaction to form a stable, wood cell wall fibril connected. The resin content more scrimber, more cell cavity containing phenolic resin, cross-linking groups are more, so as to effectively improve the corrosion resistance of scrimber. (b) compression densification cells. Dense tissue reorganization of wood structure makes the hyphae can invade the space and path of recombinant reduced. The wood density is high, the gap between the cells less, at the same time per unit volume of fiber content and phenolic resin content also increased, effectively inhibited the corrosion of decadent bacteria. (c) chemical control cells. CuAz preservatives can enter the tube well, In the cell walls of wood rays and fibers, copper complexes react with cell wall materials to effectively inhibit the growth and reproduction of decaying fungi, thus improving the antisepsis of reconstituted wood.

【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TS612

【相似文献】