重组竹胶合成型机理研究

Bamboo scrimber is a novel bamboo based composite made from bamboo bundles compressed and bonded in parallel direction. It becomes one of the main commercial products in bamboo industry. Physical and chemical changes of bamboo cells such as compressing, bonding and densifying take place during the forming process of bamboo scrimber, which influence directly the performances of bamboo scriber such as density, mechanical strength and water swelling rate. The existent study mainly focus on the forming technology, however, it would restrict the further development of industry for bamboo scrimber owing to the lack of systematic theoretical study. The response mechanism of bamboo cell wall and the formation mechanism of bonding are the key scientific problems during bamboo scrimber forming process. Therefore, in this proposal, the bamboo scrimbers are fabricated via both hot-pressing process and cold-pressing/hot-curing processes. In addition, several analytical techniques such as small-angle X-ray scattering (SAXS), solid state nuclear magnetic resonance imaging (NMRI), micro computed tomography (Micro CT) and transmission electron microscopy (TEM) are employed to investigate the cell structural changes as well as chemical, physical and mechanical properties, and to study the penetration, wettability and curing phenomenon of phenolic resin on the bamboo bundles, and then to explore the compatibility, interaction and bonding properties between bamboo cell and phenolic resin. Finally, the response mechanism of cell wall and the bonding formation mechanism of two forming methods will be revealed and then their effects on the physical and mechanical properties of bamboo scrimber will be also studied. The results of this fundamental work have a promise to provide a theoretical basis for solving the common problems in the industry of bamboo scrimber such as dimensional stability and performance modulation.

重组竹是以竹束为构成单元，按顺纹组坯后，胶合成型的一种新型竹质复合材料，是竹产业主流产品之一。在重组竹胶合成型的过程中，竹材细胞发生压缩、胶合、密实等物理化学作用，直接影响产品的密度、强度、吸水膨胀率等性能，目前的研究主要集中在成型工艺技术，缺乏系统的理论研究，制约了产业的再发展。胶合成型的核心科学问题是湿热-高压作用下细胞壁响应机制及胶合界面形成机理。本项目以热压和冷压热固化两种方法制备的重组竹为对象，采用SAXS、Micro CT、NMRI、TEM等先进设备，研究重组竹细胞壁的构造、化学组分和物理力学性能及变化规律；研究酚醛树脂在竹束中的渗透、润湿、固化等现象演变过程，与细胞壁的相容性、界面结构和胶合性能。阐明两种成型方法细胞壁的响应机制，揭示细胞壁与酚醛树脂胶合界面形成机理，探索其对重组竹物理力学性能的影响机制，为解决重组竹尺寸稳定性和性能调控等制约产业发展的共性问题提供理论依据。

本项目以“重组竹胶合成型机理研究”为突破口，以“确保我国重组竹领域继续保持世界先进水平”为总目标，紧紧围绕着材料“组分、构造和性能”这一研究主线，采用多学科交叉研究方法，从竹材细胞对“湿-热-力”响应机制和胶合界面形成机理等两方面进行了系统的研究。. 揭示了竹材细胞对“湿-热-力”和酚醛树脂作用具有选择性的现象，发现了竹材可通过选择性地增强导管、薄壁组织等薄弱相细胞从而达到材料宏观性能改善的规律；阐明了重组竹多尺度多层次胶合界面的形成机理和大压缩比下细胞形变固定的机制；剖析了重组竹跳丝和膨胀的诱因，提出了络合重组提高重组竹尺寸稳定性的技术方案，发明了竹质络合重组材料；构建了竹材定向重组工艺理论，并实现了产业化；产品在建筑结构、园林景观工程和高速公路护栏等领域得到了示范应用。研究成果在国内外学术期刊发表论文10篇（其中：SCI收录8篇）；申请发明专利2件（其中：已授权1件）；获得省部级科学技术奖二等奖1项；国家发展改革委员会将该成果列入《国家重点推广节能低碳技术推广目录（2017年版 低碳部分）》加以重点推广；国家林业和草原局对该成果组织了鉴定，以中国工程院院士李坚为组长的专家组认为：该成果达到了“国际领先水平”，并召开了科技成果新闻发布会对该成果进行发布，为竹材高效重组提供了基础理论和技术支撑。. 项目在实施过程中培养了一支具有国内外影响力的优秀青年人才和团队。研究团队荣获“全国工人先锋号”荣誉称号，项目组2名成员被遴选为省部级人才，1人被评为中国林科院杰出青年，3人次晋升为副研究员，8人次在全国学会、协会、创新联盟担任主要职务，培养博士研究生1名。项目实施期间依托研究团队组建了“中国林产工业协会竹木重组材及制品分会”、“国家林业和草原局重组材工程技术研究中心”和“重组材产业国家创新联盟”三个省部级平台，为重组竹行业的发展提供了良好的平台和人才支撑。