水热—漆酶预处理及木质素自胶合机理研究
发布时间：2019-05-14 11:53
【摘要】：随着环境污染和能源危机的日益突显,以可再生木质纤维原料制备能源、材料及化学品已成为研究的热点和重点。在积极倡导绿色环保理念,追求人与环境和谐发展的今天,结合生物质预处理技术研制开发环境友好型生物质复合材料是实现这一目标的有效途径。本文通过水热与漆酶介体预处理相结合的方法对纤维进行了界面改性,研究了水热和漆酶介体预处理之后纤维和木质素的结构变化；以竹材为原料,应用从生物乙醇发酵后的碱木质素残渣作为天然胶黏物质,采用热压的方法制备刨花板,并从中分离出木质素组分进行结构分析；为进一步研究木质素在热压过程中结构的变化,采用逐渐升高温度单独热压木质素的方法,研究了木质素在热压过程中的结构转变和胶合机理。本文主要研究内容和结果如下：(1)纤维经过水热预处理后,纤维中的一部分半纤维素和木质素降解溶出,在纤维的表面出现了孔洞和颗粒物,纤维的可及度和结晶度增加。纤维经过漆酶介体预处理后,使木质素发生了降解,分子量降低。水热和漆酶介体综合预处理后,木质素的β-O-4'连接键发生了断裂,G'型单元含量减少,S/G比率和酚羟基含量大大增加。(2)把碱木质素和竹材碎料混合,在温度180℃,压力5 MPa,时间20 min,木质素／竹材碎料=0.4的热压制备工艺条件下,获得了内结合强度达到1.36 MPa的物理机械强度。通过分析分离制备的木质素,发现热压过程中造成木质素的β-O-4'芳醚键断裂,G和H型木质素单元比例以及酚羟基的含量增加。木质素骨架中芳醚键和功能基团的转变的增加了木质素单元苯环的反应活性,有利于C-C键的形成,有效的促进了耦合交联反应的发生。(3)木质素在单独热压之后,木质素大分子骨架中β-O-4'芳醚键含量降低和分子量增加,缩合的C-C键和酚羟基含量增加。另外,随热压温度的上升,木质素的玻璃化转变温度也相应升高。总的来说,在热压过程中,木质素的断裂和交联反应是一对协同反应,同时发生。全面深刻的了解木质素在热压过程中的反应活性和化学结构转变可以为其在木质复合材料中的广泛应用提供非常有价值的方法与理论指导。
[Abstract]:With the increasing prominence of environmental pollution and energy crisis, the preparation of energy, materials and chemicals from renewable wood fiber has become the focus of research. Today, when we actively advocate the concept of green environmental protection and pursue the harmonious development of human and environment, the research and development of environmentally friendly biomass composites combined with biomass pretreatment technology is an effective way to achieve this goal. In this paper, the interfacial modification of the fiber was carried out by means of hydrothermal and laccase pretreatment, and the structural changes of fiber and lignin after hydrothermal and laccase pretreatment were studied. Using bamboo as raw material, alkali lignin residue fermented from biological ethanol as natural adhesive, particle board was prepared by hot pressing, and lignin components were separated from it for structural analysis. In order to further study the structural change of lignin during hot pressing, the structural transformation and bonding mechanism of lignin during hot pressing were studied by increasing the temperature and pressing lignin alone. The main contents and results of this paper are as follows: (1) after hydrothermal pretreatment, some hemicellulose and lignin in the fiber are degraded and dissolved, pores and particles appear on the surface of the fiber, and the accessibility and crystallization of the fiber increase. After pretreatment with laccase mediator, lignin was degraded and molecular weight decreased. After comprehensive pretreatment of hydrothermal and laccase mediators, the 尾-O 鈮，
本文编号：2476690
[Abstract]:With the increasing prominence of environmental pollution and energy crisis, the preparation of energy, materials and chemicals from renewable wood fiber has become the focus of research. Today, when we actively advocate the concept of green environmental protection and pursue the harmonious development of human and environment, the research and development of environmentally friendly biomass composites combined with biomass pretreatment technology is an effective way to achieve this goal. In this paper, the interfacial modification of the fiber was carried out by means of hydrothermal and laccase pretreatment, and the structural changes of fiber and lignin after hydrothermal and laccase pretreatment were studied. Using bamboo as raw material, alkali lignin residue fermented from biological ethanol as natural adhesive, particle board was prepared by hot pressing, and lignin components were separated from it for structural analysis. In order to further study the structural change of lignin during hot pressing, the structural transformation and bonding mechanism of lignin during hot pressing were studied by increasing the temperature and pressing lignin alone. The main contents and results of this paper are as follows: (1) after hydrothermal pretreatment, some hemicellulose and lignin in the fiber are degraded and dissolved, pores and particles appear on the surface of the fiber, and the accessibility and crystallization of the fiber increase. After pretreatment with laccase mediator, lignin was degraded and molecular weight decreased. After comprehensive pretreatment of hydrothermal and laccase mediators, the 尾-O 鈮，
本文编号：2476690
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