College of Environmental Science and Engineering, South China University of Technology, 510640 Guangzhou, China.
Bioresour Technol. 2010 Jun;101(12):4577-83. doi: 10.1016/j.biortech.2010.01.026. Epub 2010 Feb 23.
Eucalyptus pulp fibers with large differences in cellulose and hemicellulose proportions but similar lignin contents were produced by partial removal of the hemicellulose and studied using Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance (CP/MAS (13)C NMR) in combination with spectral fitting, Atomic Force Microscopy (AFM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). There were remarkable differences in both cellulose fibril structure, pore structure and cellulose supermolecular structure between the samples. CP/MAS (13)C NMR combined with spectral fitting demonstrated an increase in average fibril aggregate size (17.9-22.2 nm) with decreasing hemicellulose content. AFM observations revealed that when the hemicellulose content decreased from 27.62% to 19.80%, the average diameters of pores decreased by 12.53%, but increased by 13.55% when the hemicellulose content decreased from 19.80% to 9.09%. XRD and FTIR analysis indicated that cellulose crystallinity increased with decreasing hemicellulose content. The low and high hemicellulose-containing pulps had very different recycling characteristics, which may be explained by the changes observed at cellulose fiber structure level. Fibrils appear to aggregate and form a more compact structure when the hemicellulose is removed, which was caused by a coalescence of the cellulose microfibrils. The removal of hemicellulose had disadvantageous influence on the accessibility of fibers and enhanced fiber flattening during drying, leading to increased sheet density and increased hornification.
采用部分脱除半纤维素的方法制备了纤维素和半纤维素比例差异较大但木质素含量相似的桉木浆纤维，并采用交叉极化魔角旋转碳-13 核磁共振（CP/MAS (13)C NMR）结合谱拟合、原子力显微镜（AFM）、X 射线衍射（XRD）和傅里叶变换红外光谱（FTIR）对其进行了研究。结果表明：样品的纤维素纤维结构、孔隙结构和纤维素超分子结构均存在显著差异。CP/MAS (13)C NMR 结合谱拟合表明，随着半纤维素含量的降低，平均纤维束尺寸（17.9-22.2nm）增大。AFM 观察结果表明，当半纤维素含量从 27.62%降至 19.80%时，孔隙的平均直径减小了 12.53%，而当半纤维素含量从 19.80%降至 9.09%时，孔隙的平均直径增大了 13.55%。XRD 和 FTIR 分析表明，随着半纤维素含量的降低，纤维素结晶度增加。低半纤维素和高半纤维素含量的浆粕具有非常不同的回收特性，这可以用纤维素纤维结构水平观察到的变化来解释。当半纤维素被去除时，纤维的微纤丝可能会团聚并形成更致密的结构，这是由于纤维素微纤丝的聚并所致。半纤维素的去除对纤维的可及性有不利影响，并在干燥过程中增强纤维的扁平化，导致纸页密度增加和角质化增加。
