漂白竹浆碱抽提制备溶解浆的研究

摘要

Bamboo dissolving pulp was prepared by alkaline extraction method with bleached bamboo pulp as raw material. The cellulose crystalline structure and the fiber surface morphology from the samples treated before and after the extraction were observed by X-ray diffraction and field emission scanning electron microscope ( FE-SEM ) . The changes of molecular weight distribution (MWD) of carbohydrate were studied by the technology of gel permeation chromatography (GPC). The bamboo dissolving pulp was obtained by hydrochloric acid treatment after alkaline extraction. The results showed that the removal rate of hemicellulose was up to 66. 71% after treated by 10% of pulp concentration and 10% of sodium hydroxide concentration at 30℃for 60 min. The FE-SEM results showed that the phenomenon of surface-fibrillated fiber resuced, the fiber lateral width widened and the softness of fiber increased with the removal of hemicellulose. The GPC showed that the polydispersity with the removal of hemicellulose reduced, decreased polydispersity index ( PDI ) from 7. 71 to 4. 43, molecular weight of cellulose samples increased. Thus, the uniformity of the molecular weight distribution was improved. And the pulp after optimal alkaline extraction was subjected to subsequent acid treatment which led to 7. 02% of hemicellulose, theα-cellulose of bamboo dissolving pulp was 94. 25%.%以漂白竹浆为原料,通过碱抽提技术制备竹溶解浆,并用X射线衍射仪研究竹浆中纤维素晶型结构的变化,用场发射扫描电镜( FE-SEM )观察纤维表面形貌的变化,采用凝胶渗透色谱( GPC)分析碱抽提后竹浆相对分子质量分布( MWD)。经碱抽提后,采用盐酸进行酸处理,以调控溶解浆的聚合度、灰分和白度。研究结果表明：在浆质量分数10%条件下, NaOH 质量分数10%,温度30℃,时间60 min,半纤维素脱除率可达66.71%；FE-SEM观察到半纤维素的去除减少了纤维表面原纤化现象,增大纤维横向宽度,增加了纤维柔软性及卷曲性；GPC分析表明多分散系数(PDI)随半纤维素的去除逐渐下降,由7.71降至4.43,竹浆相对分子质量增加,提高了相对分子质量分布的均一性。酸处理过程使残余半纤维素质量分数降至7.02%,竹溶解浆纤维素纯度高达94.25%。