【作者】 余养伦；

【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， 2007， 硕士

【摘要】 我国是一个森林资源匮乏的国家，无论森林覆盖率还是人均占有量均低于世界平均水平，尤其缺乏大径级的针叶材和优质的阔叶材，而我国的竹类资源和人工林资源十分丰富，其面积和产量均居世界首位，因此，高效合理地利用竹材和人工林木材对缓解我国木材供需矛盾具有重要意义。本文选用我国南方资源丰富的毛竹（Phyllostachys pubescens Mazel exH.de Lebaie）和人工速生材尾叶桉（E.urophylla）为原料，通过对毛竹竹条和桉树单板基本物理力学性能，表面润湿性能，胶合性能和板坯热传导性能等研究基础上，从结构和工艺两个方面对竹桉复合材料重组技术进行优化设计。主要结论如下：（1）竹条的厚度对竹条基本物理力学性能影响较小，桉树单板的厚度对单板基本物理力学性能影响较大，随着厚度的增加，单板的静曲强度和弹性模量减小；采用涂胶热压处理后，桉树单板的物理力学性能得到改善，其改善程度因单板厚度、施胶量和单板的密度不同而不同。（2）环境温度对PF胶在竹条和桉树单板表面的润湿性有显著的影响，随着润湿环境温度的升高，酚醛胶在竹条和桉树单板表面的润湿性变差；堆放时间对桉树单板润湿性具有显著的影响，随着堆放时间的延长，PF胶在桉树单板表面的润湿性变差；砂磨可以在一定程度上改善桉树单板的润湿、渗透和铺展性能。（3）建立了胶合强度分布规律的评价体系。桉树、杨木和落叶松胶合强度的双尾检验P值分别为0.203、0.235和0.464，均大于0.05显著性水平，三种木材胶合板的胶合强度服从正态分布，为正偏态分布；桉树和杨木胶合板的胶合强度为尖峰态，而落叶松胶合板的胶合强度为低峰态。（4）建立了竹材和桉树单板层积材的热压升温曲线数学模型。模型的实际曲线和理论曲线的R²值在0.92以上，热压升温速率系数k值与单板的厚度、板坯层数，热压温度，热压压力，含水率呈线性相关，在热压过程中，通过调整板坯结构和热压工艺可以改善竹木复合材料板坯的热传导性能。（5）建立了适合于竹木复合材料的刚度预测模型。用该模型预测的竹桉复合材料弹性模量预测值与实验值的Pearson乘积矩相关系数R²在0.80以上，用竹材和桉树单板层积材的弹性模量预测竹桉复合材料的弹性模量，实际值与理论值相差在11％以内，模型具有一定的实际意义。（6）建立了竹木复合材料的强度定性预测的数学模型。该模型能对竹木复合材料的不同破坏类型进行定性解释；用竹桉复合材料刚度模型、强度模型和材料断裂理论，从理论上阐明了竹桉复合材料的设计原理。（7）对于单板厚度为2.25mm的13层桉树单板层积材其较优的热压工艺为：热压温度为140℃，热压时间为1min·mm^-1，施胶量为250g·m²，压缩率为16％。更多还原

【Abstract】 China is a country with short of forestry resources; whether the forest coverage rate or per capita is lower than those of the world’s average, especially lack of larger-sized softwood and high quality hardwood. Fortunately, China has plenty of bamboo resources and forest plantation, the planting area and production of which rank first in the world. So there will be a significance to use those resources with efficiency and reasonability. The Moso bamboo （Phyllostachys pubescens Mazel exH.de Lebaie） and Eucalyptus （E.urophylla） abundant in the south of China, were choused as experimental materials in this dissertation. Based on the discussion of the basic physical and mechanical properties, surface wettability of bamboo and Eucalyptus, bonding properties and the mat thermal conductivity, the dissertation optimized the technique of reconstruction for bamboo-Eucalyptus composites in structure and technology. The main conclusions obtained from the research and analysis is as follows:The effect of thickness of bamboo strips on the basic physical and mechanical properties are not significant, while the effect of thickness of eucalyptus veneer strips are very obvious, with the increase of thickness, the physical and mechanical properties decrease. The physical and mechanical properties of eucalyptus veneer strips are improved by treated with glue-spreading and hot-pressing, the improving degrees of the physical and mechanical properties are different depending on veneer thickness, glue-spread and density.The environmental temperature has a significant impact on the wettability of PF on the surface of bamboo and Eucalyptus, the wettability of the PF on the surface of bamboo and decreased with increasing of the temperature from 20℃to 100℃; stacking time of Eucalyptus veneer after peeling is of a great effect on the wettability on the surface of eucalyptus veneer, the wettability on the surface of eucalyptus decreased with the extension of storage time. Ball-milling can improve the wettability, penetration and spreading performance of eucalyptus veneer by certain extent.The systems for evaluating the bonding strength distribution were established in this paper. Two-tailed test P value of bonding strength of plywood made from plantation wood such as eucalyptus, polar and larch is 0.203、0.235and 0.464, respectively, more than significance level of 0.05. They are approximate conform to the normal distribution on the whole, however there is a certain deviation as it is asymmetric with positive bias; the bonding strength of eucalyptus and poplar plywood turned out to be leptokurtosis while larch plywood’s is platykurtic.A mathematical model of the hot-pressing temperature curve was established in this paper based on the studies of hot-pressing temperature curve of bamboo and eucalyptus laminated veneer lumber. The R²-value of the theoretical curve and the actual curve are above 0.92. The coefficient of hot-pressing temperature rate（k-value） has a linear relation with mat layers, hot-pressing temperature, hot-pressing pressure and water content, the thermal conductivity of bamboo and eucalyptus composites can be improved by adjusting mat’s structure and hot-pressing process.The stiffness prediction model suitable for bamboo-wood composites was established in this paper. The correlation coefficient R2-value of predicted and experimental value of MOE eucalyptus-bamboo composites are above 0.80, the error between experimental value and predicted value is within 11% by taking MOE of bamboo LVL and eucalyptus LVL as a basic data for properties’ design of bamboo-eucalyptus composites, therefore, the model has a great practical significance.Based on the studies of the failure mechanisms of bamboo-wood composites, a qualitative mathematical prediction model of bamboo-wood composites strength was established in this paper, which can qualitatively interpret different failure types of bamboo-eucalyptus composites. The dissertation explained the design rules of bamboo-eucalyptus composites in theory by using stiffness prediction models, strength models and material fracture theories.The preferable optimum hot-pressing process for 13-layers LVL with 2.25 mm thickness veneer is as below: temperature is 140℃, hot-pressing time is 1min·mm^-1, glue spread is 250g·m², compression rate is 16%。更多还原