Abstract:

Chemical structure of lignin separated from wheat straw after being cooked with glycerol solution was analyzed and compared with wheat straw lignin. These two kinds of lignins were both composed of three basic units，the guaiacyl unit，the syringyl unit and the hydroxyphenyl unit，where the guaiacyl unit was the main unit. The cleavage of aryl-ether linkages connecting phenylpropanoid monomers during the wheat straw cooking process forming new phenolic hydroxyl and alcohol hydroxyl groups，resulted in the UV absorption peak of glycerol lignin shifted to longer wavelength as compared with dioxane lignin. The number average molecular weight，weight average molecular weight and polydispersity of dioxane and glycerol lignins were measured by gel chromatography as 3172 and 2241，6601 and 2361，2.08 and 1.05，respectively. The relative molecular weight of glycerol lignin was smaller and more uniform than that of dioxane lignin. Therefore，glycerol lignin will have a wider use because of the narrower molecular weight distribution.

摘要：

主要对麦草经过甘油蒸煮后分离得到的木质素进行化学结构分析，并将其和麦草中原有的木质素进行对比。可知，两种木质素均是由愈创木基、紫丁香木基和对羟苯基木基3种基本结构单元组成，其中愈创木基单元为主要单元。麦草在蒸煮过程中，连接木质素苯丙烷单体的醚键在蒸煮过程中遭到不同程度的破坏，生成新的酚羟基和醇羟基，从而造成甘油木质素的紫外吸收峰较二氧六环木质素的紫外吸收峰向长波方向移动（红移）。由两种木质素的凝胶色谱可知，二氧六环木质素和甘油木质素的数均相对分子质量分别为3172和2241，重均相对分子质量分别为6601和2361，多分散系数分别为2.08和1.05。甘油木质素较二氧六环木质素相对分子质量更小更均匀，这种较窄的分子量分布有利于其更广泛的应用。