Separation, characterization and hydrogel-formation of hemicellulose from aspen wood
Separation, characterization and hydrogel-formation of hemicellulose from aspen wood
复制标题
DOI：
10.1016/s0144-8617(00)00181-8
复制
发表时间：
2000-12-01
影响因子：
11.2
通讯作者：
Kenne, L
中科院分区：
文献类型：
--
作者：
Gabrielii, I;Gatenholm, P;Kenne, L
以白杨（Populus tremula）为原料，采用碱法提取半纤维素，然后经过氧化氢处理、超滤和喷雾干燥回收。在分离过程的每个步骤中，用HPLC监测糖组成和木质素含量。尺寸排阻色谱显示相对高摩尔质量的聚合半纤维素。产物通过H-1和C-13 NMR光谱表征，发现由线性（1 -> 4）-β-连接的D-木糖主链组成，其中4-O-甲基-α-D-葡糖醛酸取代大约每八个木糖单元的2位。木质素和O-乙酰基在分离过程中被大量去除。木聚糖是可溶于热水，和成膜性能进行了检查，在各种混合物的半纤维素和壳聚糖。这些膜在某些组成下形成具有高溶胀能力的水凝胶。用广角X-射线光谱法研究了薄膜的形貌，发现纯木聚糖薄膜是结晶的，这被认为是缺乏O-乙酰基的结果。薄膜的结晶度随着壳聚糖含量的增加而降低，单独壳聚糖薄膜没有结晶度。的水凝胶的凝聚力的建议是结晶排列的聚合物和静电之间的相互作用的酸性基团在半纤维素和氨基在壳聚糖的结果。(C)2000爱思唯尔科技有限公司版权所有。
Hemicellulose from aspen (Populus tremula) was isolated by an alkali extraction method, which was followed by hydrogen peroxide treatment, ultrafiltration and recovery by spray drying. The sugar composition and lignin content were monitored with HPLC at each step of the separation procedure. Size-exclusion chromatography showed a polymeric hemicellulose of relatively high molar mass. The product was characterized by H-1 and C-13 NMR spectroscopy and was found to be composed of a linear (1 --> 4)-beta-linked D-xylose main chain with a 4-O-methyl-alpha-D-glucuronic acid substituting the 2-position of approximately every eighth xylose unit. Lignin and O-acetyl groups had largely been removed in the separation process. The xylan was soluble in hot water, and the film forming properties were examined at various mixtures of the hemicellulose and chitosan. These films formed hydrogels with a high swelling capacity at certain compositions. The morphologies of the films were examined with wide angle X-ray spectroscopy, and a pure xylan film was found to be crystalline, which was suggested to be a consequence of the lack of O-acetyl groups. The crystallinity of the films was found to decrease with an increasing amount of chitosan, and the film of chitosan alone showed no crystallinity. The cohesive forces of the hydrogels are suggested to be the result of the crystalline arrangement of the polymers and of electrostatic interactions between acidic groups in the hemicellulose and amine groups in the chitosan. (C) 2000 Elsevier Science Ltd. All rights reserved.