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纤维素是自然界中一种非常丰富的天然高分子化合物.纤维素的溶解是将这种可再生资源有效转化为高附加值产品的关键步骤,其溶解体系所用溶剂分为衍生化溶剂和非衍生化溶剂.从这两方面简要介绍纤维素的溶解体系及其机制,并对各个溶剂体系的优缺点进行简要概述,预测未来纤维素溶解体系会朝着高效、节能、环保的方向发展. 相似文献
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低温尿素溶剂法生产纤维素纤维是一种新型溶剂法纤维素纤维生产工艺,浆粕在NaOH/尿素/水的溶剂低温体系中快速溶解,溶液经过湿法纺丝得到纤维,其工艺路线生产流程较短。纤维素溶解和纺丝成形过程中几乎没有化学反应,工艺和原材料都是无毒害的。但低温尿素溶剂法溶解机理复杂,溶解条件苛刻,成品纤维的强度还有待提高。 相似文献
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功能性再生纤维素复合膜的制备及性能研究进展 总被引:1,自引:0,他引:1
纤维素是自然界中储量最大的天然高分子化合物,被认为是未来能源和化工的主要原料。然而,天然纤维素聚合度高、结晶度高的特性,使其难以溶于常规溶剂,极大限制了纤维素的应用。近年来,人们发现了多种新型纤维素溶剂体系,本文简要介绍了基于新型纤维素溶剂体系制备而来的再生纤维素膜以及一系列功能性再生纤维素基有机/无机复合膜材料。通过新型纤维素溶剂体系溶解再生得到的再生纤维素基复合膜在多孔性、热稳定性、强度等性能方面得到一定程度的改善,有望应用于包装、污水处理、传感器、生物医学等领域。本文基于再生纤维素膜及其复合膜材料的最新研究进展,对今后发展的热点方向进行了展望,旨在为纤维素溶解和功能性再生纤维素新材料的开发提供参考。 相似文献
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Various solvent systems capable of dissolving cellulose have been reported in the literature. Cuene (cupriethylene diamine hydroxide) and FeTNa (ferric sodium tartrate) are well known examples. Preliminary experiments were conducted with Cuene and FeTNa to determine if the cellulose dissolving ability of these systems could be used to bond yellow birch veneers. The results indicate that relatively high dry shear strengths, and low wet shear strengths are obtained. 相似文献
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Because cellulose triacetate is prepared from low-grade dissolving pulp, a considerable amount of the insoluble residue was present in the acetylation medium of the acetic acid/acetic anhydride/sulfuric acid system. To reduce the insoluble residues, a solvent, such as nitromethane, nitroethane, or dichloroacetic acid, added to the acetylation medium was found to be very effective for its reduction. By exploring the optimum conditions for acetylation with these solvents, nitromethane added and dichloroacetic acid added systems with solvent/acetic acid = 3/7 (v/v) were found to have a particularly high transmittance at λ = 670 nm in their acetylation solution with a low insoluble residue. The obtained acetates revealed good thermal properties similar to that from high-grade dissolving pulps. Therefore, a high quality cellulose triacetate can be manufactured from acetylation systems with even low-grade dissolving pulps with an appropriate solvent added. © 1996 John Wiley & Sons, Inc. 相似文献
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以离子液体1-丁基-3-甲基咪唑氯盐([BMIM]Cl)为溶剂,分别采用直接溶解法和间接溶解法(即在含水[BMIM]Cl中溶胀后再减压蒸馏去除多余的水使之溶解)制备了纤维素/[BMIM]Cl纺丝液,系统地比较了这两种纺丝液的流变行为及可纺性。结果表明:相同条件下,直接溶解法制备的纤维素/[BMIM]Cl纺丝液的表观黏度最大,而间接溶解法制得的纺丝液的表观黏度随着溶胀时[BMIM]Cl的初始含水率的增加而下降。与直接溶解法相比,间接溶解法制得的纺丝液溶解均匀、流动性能好、纺丝过程中断头次数少、可纺性能提高,所得到的再生纤维素纤维具有更好的力学性能。 相似文献
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采用不同方法将棉纤维活化并溶解在LiCl/DMAc极性溶液中,研究了活化方法、溶解温度、时间及LiCl浓度对棉纤维素溶解性的影响。结果表明:DMAc热活化法为较好的活化方法;提高溶解温度,延长溶解时间及提高LiCl浓度均有利于棉纤维溶解;棉纤维在LiCl质量分数为12%的LiCl/DMAc溶液中,150℃下搅拌4h,溶解度可达3%。碱活化法使棉纤维素聚合度大幅度降低,可提高棉纤维溶解度至8%。通过扫描电镜和X射线衍射方法研究了棉纤维在前处理和溶解过程中的形态和结构变化,初步揭示了纤维素高温处理后在低温下发生溶解的机理。 相似文献
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采用碱/尿素/水体系、碱/尿素/硫脲/水体系分别制备纤维素溶液,在溶解的不同阶段用超声波进行处理,并利用光学显微镜、偏光显微镜和X射线衍射对溶解效果进行表征。研究结果表明:溶解之前对纤维素原料的超声波处理主要是对纤维形态结构和超分子结构的破坏,略微增大溶解度;溶解过程中对纤维素溶液超声波处理则可以强化润胀,促进分散,显著增大纤维素的溶解度;在碱/尿素/水体系中超声波对溶解的促进作用强于在碱/尿素/硫脲,水体系中。 相似文献
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A new solvent for cellulose was prepared by dissolving copper (II) hydroxide in an aqueous solution of 1,3-diaminopropane. The solvent displays an efficiency equal to cuprammonium and superior to other previously reported metal complex solvents; a mechanism for the dissolution has been proposed. Solutions of cellulose in the new solvent were used to prepare thin cellulose membranes. 相似文献
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天然纤维素的溶解技术及其进展 总被引:8,自引:0,他引:8
本文系统介绍了近年来天然纤维素的溶解技术及其进展。内容包括天然纤维素的制备与分离、天然纤维素的溶解机理及所用的溶剂、天然纤维素溶解技术的发展趋势等。 相似文献
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As cellulose triacetate is prepared from low-grade hardwood dissolving pulp, a considerable amount of the insoluble residue was present in the acetylation medium of the acetic acid/acetic anhydride/sulfuric acid system. The characterization of this residue indicated that the insoluble residue is composed of cellulose triacetate and xylan diacetate, retaining a fiber structure of swollen form. To reduce the insoluble residues, reaction conditions for acetylation were investigated. As one of the remedies of reducing the insoluble residues, 17 different solvents were selected to add to the acetylation medium, and among these, dichloroacetic acid was found to be very effective for its reduction. The obtained cellulose triacetate could then reveal good thermal properties similar to that from high-grade dissolving pulps. Therefore, acetylation systems with an addition of an appropriate solvent can have a potential to industrially manufacture a high-quality cellulose triacetate from even low-grade hardwood-dissolving pulps, as observed in low-grade softwood-dissolving pulps. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 289–297, 1998 相似文献
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纤维素溶解体系的研究进展 总被引:5,自引:0,他引:5
综述了纤维素无机溶剂及有机溶剂的研究进展,分析比较了各溶剂体系的优缺点。其中有机溶剂中离子液体和N-甲基氧化吗啉的溶解能力最强,无机溶剂中碱/尿素或硫脲/水体系的溶解能力最强。但纤维素在各个溶解体系中都有一定程度的降解。 相似文献