碱预处理对漂白硫酸盐阔叶木浆微纤丝解离的影响

Effect of Alkali Pretreatment on Microfibril Dissociation of LBKP

采用交叉极化结合魔角旋转技术13C核磁共振(CP/MAS13CNMR)和X射线衍射(XRD)等研究了碱预处理对纤维细胞壁微区结构性质的影响,探讨半纤维素去除对纤维素微纤丝解离的影响.结果表明,随着碱处理时间的增加,半纤维素含量逐渐减少,从31.81%下降到了10.12%,使得微纤丝解离更容易,同等条件下制备所得微纤化纤维素(MFC)悬浮液表观黏度上升.同时,XRD分析表明碱处理抽出半纤维素对纤维素的晶型没有影响,特征衍射峰依然呈典型的纤维素I型衍射曲线,纤维素结晶度上升.CP/MAS13CNMR进一步定量得出了纤维素各种晶型的相对含量等信息,表明半纤维素含量减少会增加干态纤维中原微细纤维的聚集.

The influence of alkali pretreatment on the microregion structure and properties of fiber cell wall was studied using cross polarization combined with magic angle spinning technology 13C nuclear magnetic resonance(CP/MAS 13C NMR)and X ray diffraction(XRD). Also,the removal effect of hemicellulose on the dissociation of cellulose microfibrils was explored. The results showed that prolonging the time for alkali treatment could lead to a gradual decrease of hemicellulose content(from 31.81% to 10.12%),which made the microfibril dissociation easier under the same condition for MFC preparation. The apparent viscosity of prepared MFC fiber suspension increased due to the alkaline pretreatment. At the same time,XRD analysis showed that the alkali treatment had no significant effect on the crystal type of cellulose,and the characteristic diffraction peak displayed the typical cellulose I diffraction curve,with an increased crystallinity of cellulose. The relative contents of various crystal types of the cellulose were further quantified by CP/MAS 13C NMR,which indicated that the decrease of hemicellulose content would increase the aggregation of fibrils at a dried state.