自水解后杨木边材木片化学组分和结构特性的变化及其对木片碱液浸渍的影响

Changes of Chemical Composition and Structural Characteristics of Poplar Sapwood Chips After Autohydrolysis and Their Effects on the Subsequent Alkali Impregnation

中文关键词:  杨木边材木片  自水解  化学组分  结构特性  碱液浸渍

Key Words:poplar sapwood chip  autohydrolysis pretreatment  chemical composition  structural characteristic  alkali impregnation

中文摘要:

      分析了影响杨木边材木片对碱液反应性吸收的化学组分和结构特性在自水解预处理后的变化，及在碱液浸渍过程中浸渍液碱浓和浸渍温度对自水解木片浸渍效果的影响。结果表明，杨木边材木片的综纤维素、乙酰基和木素含量都随着自水解强度的增大而降低，而弱酸性基团含量则先增加后减少。在自水解预处理后，杨木导管内部的基质/侵填体得以清除，部分纹孔膜被溶解破坏。对原料木片及自水解预处理后杨木边材木片进行碱液浸渍处理后发现，木片的NaOH溶液吸收量和NaOH消耗量随自水解强度的增大而增加。自水解预处理改善了杨木边材木片的碱液浸渍效果。各类木片的NaOH溶液吸收量和NaOH消耗量均随浸渍液碱浓的增大和浸渍温度的升高而增加，且都呈现良好的线性相关性。

Abstract:

      The chemical composition and structural characteristics of the fast-growing poplar sapwood chips after autohydrolysis pretreatment were investigated. The effects of the alkali concentration and temperature of the impregnation on alkali impregnation result of autohydrolyzed chips were analyzed. The results showed that the contents of holocelluloses, acetyl groups, and lignin of the poplar sapwood chips all decreased with increasing the intensity of autohydrolysis pretreatment, while the content of weak acidic groups first increased and then decreased. After autohydrolysis, the matrix and/or tyloses in the vessels could be cleaned up, and the pit membranes of some pits could also bedissolved and damaged. The alkali impregnation experiment of both poplar sapwood chips without and with autohydrolysis found that, the amounts of adsorption of NaOH solution and consumption of NaOH of the chips increased as the intensity increase of autohydrolysis.It indicated that autohydrolysis pretreatment could improve the alkali impregnation efficiency of poplar sapwood chips. The amounts of adsorption of NaOH solution and consumption of NaOH of the both chips without and with autohydrolysis all increased as the concentration of the NaOH solution and the impregnation temperature increased, they had good linear correlations.