【作者】 孙伟圣；

【导师】 傅峰；

【作者基本信息】 中国林业科学研究院 ， 木材科学与技术， 2009， 博士

【摘要】 木材-橡胶复合材料是近年来才被提出来的一类功能型复合材料,具有良好的防水、防腐、防蛀、防静电、隔音吸音、阻尼减震、隔热保温等性能,可以用作室内装修装饰材料、隔音吸音材料、阻尼减震材料、隔热保温材料,综合体现了木材的高效利用、废旧轮胎的无污染循环利用和提高林产品附加值等方面的价值,发展前景非常广阔。但目前关于木材-橡胶复合材料的研究还处于起步阶段,尚未形成工业化产品。为了对木材-橡胶复合材料进行深入研究,通过查阅大量的文献,完成了其软木仿生结构的设计,以人工林木材、木制品加工剩余物和废旧轮胎颗粒为原料,制备了木材-橡胶复合材料并对影响其性能的主要因子进行了研究;用实验模态分析的方法揭示了木材-橡胶复合材料的静音机理,对其在静音地板中的应用进行了探索性研究。对地板制备工艺和性能、经济效益进行了分析,并对地板静音性能测试方法做了初步研究。本研究得出以下主要研究结论:1)在木材-橡胶复合材料的软木仿生结构中,木材相当于软木细胞壁物质,起到支撑、填充作用,主要提供物理力学性能,是结构中的强度单元;橡胶相当于软木细胞腔中的密闭气体,起到类似弹簧的作用,是结构中的减震单元;胶粘剂一定程度上相当于软木细胞壁中的软木脂,主要起到结构单元之间的胶接作用。2)制备工艺对木材-橡胶复合材料性能的影响规律主要有:木/橡胶质量比对材料性能影响极显著。随着木/橡胶质量比的减小,橡胶颗粒用量增大,材料的耐吸水膨胀性能增强,内结合强度减小,静曲强度和弹性模量降低,固有频率下降,阻尼比升高,撞击声减小,撞击声改善值增大。木材形态对材料影响显著。使用扁平刨花和纤维可以获得较好的物理力学性能,C型刨花制备的材料具有较低的固有频率和撞击声、较高的阻尼比和撞击声改善值。施胶量对木材-橡胶复合材料物理力学性能的影响极显著(2 h吸水厚度膨胀率除外),对振动及声学性能的影响不显著。密度对物理力学性能、振动及声学性能的影响都非常显著。木材-橡胶复合材料的目标密度在0.8~1.0 g/cm3范围内可获得较好的综合性能。木/橡胶质量比和施胶量之间、密度和加压时间之间的交互作用对物理力学性能、振动及声学性能都有很大影响。因此,在调整工艺参数时,应将交互作用考虑在内。3)具有良好减震降噪性能的较佳工艺参数:木材形态:C型刨花;废旧轮胎颗粒粒径:2~3 mm;木/橡胶质量比:40/60;施胶量:6%;目标密度:0.8 g/cm3;加压时间:4 min;压板温度:140℃。采用该优化工艺制备的木材-橡胶复合材料的主要性能如下:密度:0.78 g/cm3;2 h吸水厚度膨胀率:3.12%;内结合强度:1.1 MPa;静曲强度:3.8 MPa;弹性模量:342 MPa;固有频率:17.4 Hz;阻尼比:0.15;撞击声:76.5 dB(A);撞击声改善值:15.5 dB(A)。4)木材-橡胶复合材料的静音机理:大量橡胶颗粒的存在,使得木材-橡胶复合材料具有较低的固有频率和较高的阻尼比。在冲击载荷作用下,由于木材-橡胶复合材料各阶频率间距较小,容易产生共振,使得材料中的橡胶颗粒减震吸能的功能得到充分发挥,材料整体的减震降噪功能提高;同时,较高的阻尼比可以加快振动的衰减,能量在传递过程中耗散较大,降低了以声能形式耗散的能量,起到减震降噪作用。5)采用撞击声和撞击声改善值两个参数指标对地板静音性能进行评价,提出了一种地板静音性能测试方法——自由落球撞击法,设计并制作了一套相应的测试系统。实验证明,自由落球撞击法可以对不同静音性能的地板做出精确的定量评价,具有所需试件少、测试快速简便、结果准确的特点。6)以木材-橡胶复合材料为基材的新型静音地板(WRC静音地板),通过不同的结构设计,可以获得良好的静音性能和物理力学性能;在外部载荷作用下,WRC静音地板的弯曲破坏类型有2种。更多还原

【Abstract】 Wood-rubber composite (WRC) is a new kind of functional composite which comes up in recent years. It has many good performances, for example, waterproof, antiseptic, mothproof, antistatic, soundproof and sound absorption, vibration damping, heat insulation, and so on. Therefore, it can be widely used as indoor decoration materials for sound insulation, vibration damping and heat insulation. The development of WRC will show high-efficient utilization of wood, pollution-free recycled utilization of waste tyre and high-added value of forest products. Therefore, this composite has broad prospects. However, as the research work is just in a beginning stage, the industrialized production of WRC has not been realized yet.In order to gain a deep study on WRC, a lot of correlative literature was consulted, and the bionic design of WRC is obtained based on cork microstructure. According to the structure model, WRC was made of plantation wood, woodwork remainder and waste tyre particles. The main factors which affect the performances of WRC were studied in this paper. In addition, the soundproof mechanism of WRC was disclosed through experimental modal analysis. At the same time, the application of WRC in manufacturing wood-based soundproof flooring was experimentally studied, and the manufacturing process, performances and economic benefit were analyzed. The testing method of soundproof property was also studied.The main research results are as follows:1) In the bionic structure of WRC based on cork microstructure, wood particle is just like the cell wall, playing the role of supporting and filling. In WRC, wood particle is the strength element, which shows physical and mechanical properties; The rubber, just like the gas enclosed in cork cell lumen, plays an important role like spring in vibration damping; And adhesive is in some degree like the suberin with the function of connection.2) The main relationships of process and performance are as follows:The mass ratio of wood to rubber has a significant effect on the performances of WRC. With the reduction of the ratio, the amount of rubber particles increases, which makes the water absorption and swelling resistance of WRC increase, and makes the internal bond strength, modulus of rupture, modulus of elasticity, natural frequency and impact sound decrease; But, on the contrary, the damping ratio and improvement of impact sound insulation increase.The configuration of wood particles has a significant effect on the performances of the composite. Better physical and mechanical properties can be gained using flat wood particles and fibre. C-type wood particles can make WRC with lower natural frequency and impact sound, higher damping ratio and improvement of impact sound insulation.The resin content has a significant effect on the physical and mechanical performances (except thickness swelling rate of water absorption within two hours), but it does not have obvious effect on vibration and acoustic performances according to the results of experiment.The density of the composite has a significant effect on physical and mechanical, vibration and acoustic performances. WRC with the target density from 0.8 g/cm3 to 1.0 g/cm3 has better comprehensive performances.The interaction of the mass ratio of wood to rubber with the resin content, and that of the density with pressing time have some significant influence on the performances. Therefore, the interaction should be taken into account when process parameters are adjusted.3) In order to obtain better vibration and acoustic performances, the better process parameters are as follows: C-type wood particles, 2-3 mm waste tyre particles, the mass ratio of wood and rubber 40/60, the resin content 6%, the target density 0.8 g/cm3, the pressing time 4 min and the hot pressing temperature 140℃. By adopting the optimized process, the main performances of WRC are as follows: density 0.78 g/cm3, thickness swelling rate of water absorption within two hours 3.12%, internal bond strength 1.1 MPa, modulus of rupture 3.8 MPa, modulus of elasticity 342 MPa, natural frequency 17.4 Hz, damping ratio 0.15, impact sound 76.5 dB(A) and the improvement of impact sound insulation 15.5 dB(A).4) The mechanism of soundproof of WRC: Low natural frequency and high damping ratio due to the existence of large amount of rubber particles in the structure. Under the load of impacting, it is easy to generate sympathetic vibration because of the narrow space between different order frequency, and then the rubber particles’function of vibration damping and power absorption can be fully realized. At the same time, higher damping ratio can attenuate vibration. More energy dissipated in the course of transmission can reduce energy dissipation in the form of sound, thus vibration and noise are also decreased.5) The soundproof property can be evaluated with two parameters: impact sound and improvement of impact sound insulation. A new method called free-dropping-ball impacting method was put forward for testing soundproof property, and a set of testing system was designed and prepared. The feature of this testing method is: a few samples, easy and quick test and precise evaluation. This research will offer a new idea for drafting and developing testing method standards of wood-based soundproof flooring in future.6) The better soundproof and physical mechanical performances can be achieved through changing the structure of WRC-based soundproof flooring; Under exterior load, three kinds of forces are acted on WRC layers (tension, extrusion and shearing). There are two types of bending failure for WRC-based soundproof flooring.更多还原