【作者】 于雪斐；

【导师】 于文吉；

【作者基本信息】 中国林业科学研究院 ， 木基复合材料科学与工程， 2012， 博士

【摘要】 竹基纤维复合材料的研发成为近年来生物质材料领域的研究热点。纤维化竹单板层积材是一种竹基纤维复合材料，它是由纤维化竹单板单元和胶粘剂层构成，纤维化竹单板层积材以其优越的物理力学性能，结构可设计性，性能可调控等特点，既可以用于工程结构材料如风电材料、建筑水泥模板材料、集装箱底板以及车厢地板材料，也可以用于室内外地板材料、家具材料、装饰装潢材料的制造；既符合目前低碳经济发展的需要，也可以有效解决我国木材资源供应不足的问题；既可以推动我国竹材产业的发展，提高了我国竹材资源利用率，高效利用竹材资源，也提高竹产区竹农的收入，具有极为广阔的应用前景。本论文以慈竹（Neosinocalamus affinis （Rendle） Keng f.）为主要研究对象，对纤维化竹单板单元进行评价，采用不同热压温度（130℃、140℃、150℃和170℃）和施胶量（7%、9%、10%和11%）制造不同密度（1.0g/cm3、1.1g/cm3、1.15g/cm3和1.2g/cm3）的纤维化竹单板层积材，并分析压板工艺对纤维化竹单板层积材的物理力学性能的影响。通过对不同压板工艺下的纤维化竹单板层积材的耐老化性和耐疲劳性的研究，揭示了纤维化竹单板层积材的性能变化规律，并探讨了纤维化竹单板广泛应用于高强度结构用材的可能性。主要研究结论如下：（1）不同疏解次数的纤维化竹单板的吸水率、吸胶率和吸附性能随着疏解遍数的增加而增加。纤维化竹单板等温吸附曲线均呈反S型，各试样的低温氮吸附等温线在升压过程的吸附等温线和降压过程的脱附曲线不重合，形成吸附回线，属于IV型等温线。滞留回环的类型属于H4的情况，纤维化竹单板中的孔道形状符合经典孔道模型。疏解机对纤维化竹单板上表面的竹青去除显著，竹纤维之间从基本组织部分被分离成相互粘连的束状，但纵向上保持完整纤维的形态，几乎没有断裂，竹黄的孔隙较多，碎裂的相对明显。（2）随着密度的逐渐升高，板材力学强度逐渐升高，吸水率和吸水厚度膨胀率降低。随着热压温度升高，板材的力学强度逐渐降低，吸水率和吸水厚度膨胀率略有降低。施胶量提高时，试材力学强度和24h吸水率有所降低。热压过程中板材升温速率随着密度的增加而降低，施胶量对升温速率影响不明显。本论文试验中不同压板工艺下的纤维化慈竹单板层积材，其主要力学性能均符合JB/T10194-2000《风力发电机组风轮叶片》的要求，其中密度为1.2g/cm3，施胶量10%的板材性能最优。对热压处理过的板材和未经处理的原竹材进行FT-IR分析发现，光谱谱带形状几乎一致，热压对竹材的组织结构和主成分几乎没有影响。热压过程中羟基的减少，导致吸水性降低，尺寸稳定性提高，半纤维素的损失削弱竹材及板材的力学强度。对板材进行扫描电镜观察可知在热压过程中，薄壁组织被压溃，竹纤维受热压的影响不明显。（3）加速老化后的板材的静曲强度和弹性模量，随着密度的增高而逐渐增加，和未处理前的板材强度相比，密度高的板材强度变化率相对大些。在同样的密度下，热压温度高的纤维化竹单板层积材的力学强度，略低于热压温度相对低的板材。从方差分析可知，密度对弯曲强度和垂直剪切强度的影响不显著，对弹性模量影响显著。热压温度对弯曲强度和弹性模量的影响不显著，对垂直剪切强度的影响显著。纤维化竹单板层积材有自身调节尺寸稳定的能力，密度高且热压温度高的板材有较好的尺寸稳定性。综合评定可以得出，密度为1.2g/cm3，施胶量10%，热压温度为130℃的板材性能最优。（4）板材可能承受最大的应力，随着两端施加的交变循环力的循环次数增加而降低。在循环103，104，105，106次后，纤维化竹单板层积材所能承受的最大应力分别为115MPa，110MPa，105Mpa和98MPa。从103次至106次，板材能承受的最大应力较原始静态抗拉强度下降了65.7%至70.7%，和铝、碳复合材料、钢制品、木单板层积材和玻璃纤维的S-N曲线相比，纤维化竹单板层积材有着更稳定的强度保持能力。更多还原

【Abstract】 The research and development of bamboo-based fibrous composite has been the researchhotspot of bio-based materials. Bamboo laminated veneer lumber is a kind of bamboo-basedfibrous composite which is made of crushed bamboo veneer and adhesive. Bamboo laminatedveneer lumber has advantages such as high physical and mechanical performance, structuredesignability and regulatable performance etc.. Bamboo laminated veneer lumber can bewidely used in engineering structure materials and decoration materials, such as wind turbineblade, building cement template, container flooring, the floor of outdoor and indoor, carriagefloor and furniture. Bamboo laminated veneer lumber is endowed with promising future as aresult of geared to the developing of low carbon economy requirement by effective resolvedthe problem of inadequate timber resources in China, promoted the take-off of the bambooindustry by increase bamboo operation rate and increase farmers income in bamboo producedistrict.In this paper, Neosinocalamus affinis was used to make the laminated veneer lumber withdifferent hot pressing temperature (130℃,140℃,150℃and170℃), resin content (7%,9%,10%and11%) and density (1.0g/cm3,1.1g/cm3,1.15g/cm3,1.2g/cm3). First, crushed bambooveneer has been evaluated. Then analyzed the influence of physical and mechanical propertiesfor bamboo laminated veneer lumber. The change law of properties by bamboo laminatedveneer lumber were shown through tested aging resistant and fatigue durability. Thepossibility of the application of bamboo laminated veneer lumber was discussed at last. Themain results were summarized as follows,（1）As the times of crushing was increased, the water absorbing capacity, gum absorbingcapacity and adsorptive properties were improved. The isothermal adsorption curve of bamboolaminated veneer lumber appeared reverse “S” and the lifting pressure curve was notcoincident with the reduction pressure curve. The adsorption loop belongs to class IV and the type of retention loop belongs to situation H4. The pore shape of crushed bamboo veneer thatconforms to the classical pore model.The crushing machine bring about a striking effect on removing the outer surfaces ofbamboo. Bamboo fiber sticking to each other, but maintained the integrity of fiber morphologyalong the length of fiber, almost had no rupture. The inner of bamboo disintegrated relativeobviously which has more hole.（2）The mechanical strength of bamboo laminated veneer lumber increased with theincrease of density, water absorbing capacity and thickness swelling rate reduced at the sametime. The mechanical strength, water absorbing capacity and thickness swelling rate reducedas the hot pressing temperature increased. The mechanical strength and24h water absorbingcapacity reduced when resin content raised. Heating rate increased as the density reducedduring the hot-pressing process. The effect of heating rate by resin content was not obvious.The mechanical strength of bamboo laminated veneer lumber with hot pressingtemperature (130℃~170℃), resin content (7%~11%) and density (1.0g/cm3~1.2g/cm3)complied with the standard wind turbine rotor blade. Bamboo laminated veneer lumber withresin content of10%and density of1.2g/cm3had the best performance.FT-IR analysis of bamboo laminated veneer lumber showed that the molecular bandshape of bamboo laminated veneer lumber were similar to the untreated bamboo. The basiccomposition of bamboo made no obvious difference after hot press. The reduction of hydroxyled to the reduction of water absorbing capacity and the raise of dimension stability. The lossof hemicellulose weakened mechanical strength of bamboo laminated veneer lumber.Scanning electron microscope analysis of bamboo laminated veneer lumber showed thatparenchyma was crushed during hot-pressing process. The effect of bamboo fiber by hot presswas not obvious.（3）Modulus of elasticity and modulus of rupture by bamboo laminated veneer lumberafter accelerated aging increased as density upgraded. Compared with the mechanical strengthof bamboo laminated veneer lumber which before accelerated aging, the changing rate ofmechanical strength were relatively higher on high density bamboo laminated veneer lumber. Under the same density, mechanical strength of bamboo laminated veneer lumber with higherhot-pressing temperature a little less than bamboo laminated veneer lumber with lowerhot-pressing temperature. Variance analysis showed that density which had no significanteffect on modulus of rupture and vertical shear strength had significant effect on modulus ofelasticity, hot-pressing temperature which had no significant effect on modulus of elasticityand modulus of rupture had significant effect on vertical shear strength.Bamboo laminated veneer lumber had the ability of dimension stability which waspreferable with high density and hot pressing temperature. Assessment concluded that bamboolaminated veneer lumber with hot pressing temperature of130℃, resin content of10%anddensity of1.2g/cm3had the best performance.（4）The maximum stress which bamboo laminated veneer lumber can support reduced asthe times of fluctuating and cyclic stresses which pressured at the two ends of the samplesincreased. Bamboo laminated veneer lumber acted upon by fluctuating and cyclic stresses of103,104,105and106times. The maximum stress of bamboo laminated veneer lumber were115MPa,110MPa,105Mpa and98MPa, respectively. The tensile strength of bamboolaminated veneer lumber after103to106times of fluctuating and cyclic stresses reduced65.7%to70.7%than the original one. Bamboo laminated veneer lumber has better strengthretentiveness than Aluminium, carbon composite material, steel, wood laminate and fiberglass.更多还原