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木质素分离及主要物理和力学性能的研究进展OA北大核心CSTPCD

Research progress in isolation,main physical and mechanical properties of wood lignin

中文摘要英文摘要

木质素是木材细胞壁的重要组成成分,其吸湿特性、热特性、力学特性等在木材的微宏观尺度相互影响,并对其高值化应用起决定性作用.本文从分子结构、分离方法、吸湿特性、热特性、力学特性五个方面综述了木材木质素的研究进展.木材木质素是高异质、不规则的三维网状高分子结构,相比原位木质素,不同分离方法的分离木质素有不同程度的解聚缩合,导致分离木质素分子结构、吸湿性、热特性、力学特性存在差异性.木材木质素具有近似 S型等温吸附曲线且存在吸湿滞后现象,平衡含水率在20%(质量分数)以下,可用 BET,GAB理论定性描述和定量分析单层水分子吸附量.木材木质素在低温时具有高分子塑性特征,玻璃化转变温度为90~160℃,高温度时具有热固性特性并发生热分解,先后发生α-O-4、β-O-4、脂肪烃碳碳键、5-5、4-O-5键断裂,类原位木质素活化能为82~150 kJ/mol.木质素在力学特性上各向同性,弹性模量总体随含水率的增大而减小,弹性模量为2.8~9.0 GPa,剪切模量为1.1~2.3 GPa,但研究范围局限在弹性阶段.在原位木质素绿色高效分离方法、木质素分子结构序列和木质素弹塑性力学性能等方面有待进一步深入研究.

Lignin is an important component of wood cell wall,and its moisture absorption characteristics,thermal characteristics,and mechanical characteristics influence each other at the micro-macro scale of wood,and play a decisive role in its high-value application.In this paper,the research progress of wood lignin was reviewed from five aspects:molecular structure,separation methods,moisture absorption characteristics,thermal characteristics and mechanical characteristics.Wood lignin is a highly heterogeneous and irregular three-dimensional network polymer structure.Compared with in-situ lignin,the lignin separated by different separation methods has different degrees of depolymerization condensation,which leads to differences in molecular structure,hygroscopicity,thermal properties and mechanical properties.Wood lignin has an approximate S-shaped isothermal adsorption curve and there is a hysteresis phenomenon of moisture absorption.The equilibrium moisture content is below 20%(mass fraction),and the BET and GAB theories can be used to qualitatively describe and quantitatively analyze the adsorption capacity of monolayer water molecules.Wood lignin has high polymer plasticity at low temperatures with a glass transition temperature of 90-160℃,and has a thermosetting property and thermal decomposition at high temperature,with α-O-4,β-O-4,carbon-carbon linkages of aliphatic hydrocarbons,5-5 and 4-O-5 linkages breaking successively,and the activation energy of pseudo in-situ lignin is 82-150 kJ/mol.The mechanical properties of lignin are isotropic,and the elastic modulus is decreased with the increase of moisture content,with the elastic modulus of 2.8-9.0 GPa and the shear modulus of 1.1-2.3 GPa,but the research scope is limited to the elastic stage.The green and efficient separation method of in-situ lignin,the molecular structure sequence of lignin and the elastic-plastic mechanical properties of lignin need to be further studied.

周博鑫;沈姿伶;江京辉;漆楚生;戴璐

北京林业大学 木质材料科学与应用教育部重点实验室,北京 100083中国林业科学研究院 木材工业研究所,北京 100091

化学

木材木质素分子结构热特性吸湿特性力学特性

wood ligninmolecular structurethermal characteristichygroscopic propertymechanical property

《材料工程》 2024 (002)

122-134 / 13

国家自然科学基金面上项目(31870536)

10.11868/j.issn.1001-4381.2022.000949

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