Isolation of Nanocellulose from Pomelo Fruit Fibers by Chemical Treatments

This study aims to isolate cellulose nanofibers from locally abundant pomelo fruit. The peels were subjected to alkali treatment (NaOH) with different concentrations and soaking times. Acid hydrolysis was also carried out to obtain an aqueous suspension of nanocellulose. The treated cellulose fibers were characterized by various methods. Alkali treatment was able to remove noncellulosic constituents. Microscopy techniques yielded morphology of elementary fibers with a compact structure with both micro- and nano-scaled fibers. An improved onset of degradation was likely caused by an increase in crystallinity evidenced by X-ray diffractometry (XRD). Acid hydrolysis could successfully individualize cellulose nanofibers as observed by transmission electron microscopy (TEM).     

纤维素的研究进展

纤维素是自然界最丰富的有机高分子,具有可再生、绿色和生物相容性,不仅在制浆造纸产品中得到大宗应用,也是化学化工的重要基础原材料。本文主要对纤维素的溶解、化学改性、纳米纤维素制备和纤维素/纳米纤维素新材料等方面的研究进展进行了综述。     

纳米纤维素作为药物载体的研究进展

药物载体(Drug Delivery)通常由高分子纳米材料构成,可以控制药物释放速率,实现药物靶向运输功能。纳米纤维素具有良好的生物相容性、低毒性和可降解性等优良性能,可作为一种理想的新型药物载体材料。本文总结了近几年纤维素纳米晶体、纤维素纳米纤丝、细菌纤维素等作为药物载体的研究进展,并对其与药物分子的结合方式做了简单的介绍。     

微纳米纤维素材料的微流控制备技术研究进展

为深入分析微流控技术制备微纳米纤维素材料的研究现状,促进其在各领域应用,综述了以纤维素及纳米纤维素为原料,以微流控技术为基础,结合快速冷冻法、原位界面络合法等技术,制备纤维素及纳米纤维素微球和微胶囊、纤维长丝、薄膜、微管、水凝胶的最新研究进展;针对微流控技术制备微纳米纤维素材料存在的挑战,提出了克服材料缺陷,提升微通道构建能力,探索技术结合方案的应对策略;展望了微流控技术在制备微纳米纤维素材料方面的发展前景,为微流控技术制备微纳米纤维素材料在材料科学、组织工程和再生医学等领域的应用提供参考。     

Application of Cellulose and Cellulose Nanofibers in Oil Exploration

In this article, the application of cellulose and cellulose nanofibers in oil exploration was discussed, and the research status of using cellulose and cellulose nanofibers as oil displacement agents, oil-well cementing additives, and foam stabilizers were summarized.     

Preparation using Pectinase and Characterization of Nanofibers from Orange Peel Waste in Juice Factories

This study reports the preparation and characterization of nanofibers consisting mainly of cellulose microfibrils from orange peel (OP), which is a significant byproduct of orange juice production. Three treatments (boiling, alkaline, and pectinase) were investigated with and without subsequent grinding treatment. It was possible to prepare the cellulose nanofibers (CNFs) using these methods, except for the boiling treatment with grinding. Interestingly, only pectinase and a mild‐physical blender treatment without grinding produced nanofibers. The width of the nanofibers from OP was approximately 10 to 50 nm. The microfibril bundles of OP were considered to be thinner than those of commercial CNFs. Our data indicated that the removal of pectic polysaccharides and hemicelluloses covering the cellulose microfibrils was important for the preparation of nanofibers from OP. These nanofibers from OP using pectinase are proposed to be applicable as food materials, pharmaceuticals, and filters for the tractive characteristics of the sheet.     

纤维素资源的开发及利用新进展

文章介绍了纤维素资源开发的一些最新进展,包括纳米纤维素、新型成网技术、绿色纤维素产品以及醋酯纤维的开发等。在此基础上探讨了新形势下我国再生纤维素纤维行业的发展路径。     

芳纶/醋酸纤维素纳米纤维的制备及表征

醋酸纤维素在N,N-二甲基乙酰胺(DMAc)中难以进行静电纺丝,将其与芳纶溶液混合后成功制备了芳纶/醋酸纤维素纳米纤维.芳纶/醋酸纤维素混合溶液有利于静电纺丝,当芳纶与醋酸纤维素质量比大于1∶2后即可获得均匀的纳米纤维.随混合溶液中芳纶与醋酸纤维素的质量比和溶液质量分数的提高,纳米纤维中的珠状缺陷逐渐减少.芳纶/醋酸纤...     

甘薯渣纤维素粒度对去势大鼠血脂降低效果的影响

目的：探讨纤维素粒度对其降血脂效果的影响。方法：选用40 只雌性SD大鼠随机分组为5 组,其中1 组大鼠进行伪切除手术作对照,另外4 组大鼠做双侧卵巢切除手术,基础饲料喂养恢复1周后,分为空白组、普通纤维素组、超微纤维素组和纳米纤维素组,实验期28 d后解剖,测定血浆和肝脏中脂质指标。体外检测3 种粒度纤维素的消化性和吸附性能。结果：3 种粒度纤维素对油脂、胆固醇和胆酸钠都有较强吸附,对油脂和胆酸钠的吸附能力随纤维素粒度减少而增加。3 种纤维素均降低双侧卵巢切除大鼠血浆总胆固醇、甘油三酯、低密度脂蛋白胆固醇浓度和动脉硬化指数值以及肝脏中总脂肪、甘油三酯的浓度。纤维素粒度与双侧卵巢切除大鼠血浆总胆固醇、甘油三酯、低密度脂蛋白胆固醇浓度呈正相关性。结论：减小纤维素粒度有利于增加纤维素对油脂和胆酸盐的吸附能力,提高纤维素降低双侧卵巢切除大鼠血脂的效果。     

一锅法合成氨基化纳米纤维素及其性能表征

为实现纳米纤维素衍生物的绿色高效制备,以过硫酸铵为氧化剂,基于机械力化学作用,在微波-水热条件下氧化降解竹浆粕得到羧基化纳米纤维素(CNC),然后与二乙烯三胺发生缩合反应,实现水相中氨基化纳米纤维素(ACNC)的一锅法合成,并对其性能进行研究。结果表明:ACNC呈棒状,直径为10~40 nm,长度为50~300 nm, 氨基的接枝率为6.29%;ACNC的晶型并未发生改变,仍为纤维素Ⅰ型,结晶度由竹浆粕的59%增加到79%;ACNC的热稳定性较竹浆粕并未显著下降,但较CNC显著提高,说明CNC表面接枝氨基后热稳定性能得到改善;该制备方法绿色高效,得到的纤维素衍生物有望在生物固化和物理性能增强方面发挥作用。     

纳米纤维素增强可生物降解聚合物的研究进展

本文综述了纤维素纳米晶体(CNC)和纤维素纳米纤丝(CNF)在增强可生物降解聚合物中的研究进展。主要介绍了两种纳米纤维素及其制备方法,阐述了纳米纤维素的增强机理和复合材料的构筑方法,详细论述了纳米纤维素在增强聚乳酸(PLA)、热塑性淀粉(TPS)、聚己内酯(PCL)应用的研究进展。最后简要分析了纳米纤维素增强可生物降解聚合物在规模化和产业化上面临的挑战,并展望了其应用前景。     

静电纺丝和炭化法制备纳米纤维素储能材料研究进展

为促进纳米纤维素材料在储能领域的应用,综述了以其为原料,采用静电纺丝和炭化技术以及2种方法结合制备用于电池和超级电容器等电极材料和隔膜材料的工艺。通过分析发现:静电纺纳米纤维素材料具有电化学性能优异、柔性较好等优点,可用作增强材料与导电材料复合使用;炭化处理纳米纤维素材料具有独特微孔结构,比表面积大等特点,其存在的形态主要有气凝胶、纳米纤维膜及薄膜等;重点分析了2种方法叠加制备纳米纤维素材料在储能领域应用中存在的问题;提出构建环保、形态结构多样的天然基材储能器件是未来的发展方向,指出静电纺丝和炭化制备纳米纤维素材料在柔性储能器件和小巧型移动端储能设备中具有较好应用前景。     

Nanocellulose-based fibres derived from palm oil by-products and their in vitro biocompatibility analysis

Abstract

Fibres with nanocellulose isolated from oil palm empty fruit bunches (OPEFBs) were produced. Nanocellulose and PVA-nanocellulose fibres were prepared by wet spinning in an acetone coagulation bath without drawing. The addition of nanocellulose was varied from 10% to 30%, to reveal the beneficial effects of nanocellulose content on the properties of produced spun-fibres. Higher concentration of nanocellulose increased the stiffness of spun-fibres. PVA and PVA-bacterial cellulose fibres were also produced as a control and for comparison, respectively. The nanocellulose fibre formed a compact structure, while PVA fibres had hollow structures. The effect of the produced spun-fibres on the biocompatibility of calf pulmonary artery endothelial cells was assayed by an MTT test. Based on the MTT assay the addition of nanocellulose increased the percentage of cell viability of the obtained spun-fibres slightly. These results point towards the use of sustainable sources of nanocellulose as a beneficial and biocompatible fibre material.     

Application of Cellulose Nanofibril as a Wet-end Additive in Papermaking: A Brief Review

Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceutical applications,as well as in industrial applications such as paints,drill muds,packaging,and papermaking.The application of CNF in papermaking is expected to be implemented in the near future to broaden the commercial market of cellulose.Numerous studies and patents have reported on the manufacturing,properties,and applications of nanocellulose.This present paper focuses on the recent progresses in the application of CNF as a wet-end additive in papermaking.     

High-value Applications of Nanocellulose

Nanocelluloses, obtained from the biopolymer cellulose, are a class of renewable functional nanomaterials with excellent properties and a broad range of applications. This review mainly illustrates practical and advanced applications of nanocellulose-based materials in the following categories. ① Fire-resistant materials: in the section on these types of materials, the fire-protection property of nanocellulose/clay hybrid composites (clay nanopaper) is illustrated; oriented montmorillonite (MTM) provides barrier properties and low thermal conductivity whereas cellulose nanofibers (CNFs) impart favorable charring. ② Thermal insulation materials: the best way to obtain materials with good heat insulation performance is to decrease the thermal conductivity of such materials. ③ Template materials: nanocellulose can direct the deposition and patterning of materials to form nanoparticles, nanowires, or nanotubes with improved properties.     

Simultaneous Extraction of Carboxylated Cellulose Nanocrystals and Nanofibrils via Citric Acid Hydrolysis—Sustainable Route

In this study, cellulose nanocrystals (CNC) with surface carboxylic groups were prepared from bleached softwood pulp by hydrolysis with concentrated citric acid at concentrations of 60 wt%~80 wt%. The solid residues from acid hydrolysis were collected for producing cellulose nanofibrils (CNF) via post high-pressure homogenization. Citric acid could be easily recovered after hydrolysis reactions through crystallization due to its low water solubility or through precipitation as a calcium salt followed by acidification. Several important properties of CNC and CNF, such as dimension, crystallinity, surface chemistry, thermal stability, were evaluated. Results showed that the obtained CNC and CNF surfaces contained carboxylic acid groups that facilitated functionalization and dispersion in aqueous processing. The recyclability of citric acid and the carboxylated CNC/CNF give the renewable cellulose nanomaterial huge potential for a wide range of industrial applications. Furthermore, the resultant CNC and CNF were used as reinforcing agents to make sodium carboxymethyl cellulose (CMC) films. Both CNC and CNF showed reinforcing effects in CMC composite films. The tensile strength of CMC films increased by 54.3% and 85.7% with 10 wt% inclusion of CNC and CNF, respectively. This study provides detailed information on carboxylated nanocellulose prepared by critic acid hydrolysis; a sustainable approach for the preparation of CNC/CNF is of significant importance for their various uses.     

Effect of Green Gram Husk Nanocellulose on Banana Fiber Composite

Nanocellulose is a significant bio entity in the present-day applications of nanocomposites. In this regard, the present work focuses on fabrication of green gram husk cellulose-based hybrid nanocomposites. In the process of nanocellulose extraction, residues obtained after each stage of treatment are characterized through physical and morphological tests. Later, nanocellulose is reinforced in unsaturated polyester with 1, 3, 5, and 7 wt. % to study the tensile properties. The peak tensile strength is found to be 39 MPa at 5wt% of cellulose nanocomposites. Noting the enhancement in tensile properties of nanocomposites, nanocellulose is reinforced in banana fiber composites and its influence on mechanical properties is studied. Nanocellulose/banana fiber hybrid composites showed enhanced tensile strength, flexural strength, and impact strength.     

低共熔溶剂在纳米纤维素制备中的应用和研究进展

低共熔溶剂(DES)是由氢键供体和氢键受体混合而成的具有低熔点的混合物,作为一种绿色溶剂,DES在化学、材料、生物催化和生物质精炼等领域有着广泛的应用前景。由于DES可以使纤维素润胀,并减弱纤维素分子链之间的氢键结合,所以DES可以被应用于纳米纤维素的制备。而且DES容易回收和回用,可以使纳米纤维素的制备过程清洁、无污染。本文综述了DES法制备纳米纤维素的原理、工艺和研究进展,并讨论了DES法制备纳米纤维素需要注意的问题。     

纳米纤维素对小麦淀粉糊化和流变特性的影响

将不同比例微晶纤维素(microcrystalline cellulose,MCC)、纳米晶体纤维素(nanocrystaline cellulose,NCC)、纳米纤化纤维素(nanofibrillated cellulose,NFC)与小麦淀粉(wheat starch,WS)复配,对比研究纳米纤维素对小麦淀粉糊化和流变特性的影响。结果表明:NCC和NFC的加入均会使起始糊化温度降低,峰值和终值黏度升高,促进淀粉的糊化,且NFC的作用效果更明显;MCC则会阻碍淀粉的糊化,抑制淀粉的短期回生。NCC和NFC会促进小麦淀粉糊化时更多可溶性直链淀粉的渗出,与MCC相比显著提升小麦淀粉凝胶的持水能力。Power-Law方程拟合静态流变数据发现:MCC、NCC、NFC加入后小麦淀粉凝胶仍为假塑性流体,NCC和NFC可显著提高小麦淀粉凝胶的K值,是良好的增稠剂。动态流变试验发现NCC和NFC的加入增强了小麦凝胶的弹性,凝胶的结构更为致密,质地更坚硬。     

纳米纤维素在食品行业中应用研究进展

概述了纳米纤维素的种类,包括微纤化纤维素、纳米纤维素晶体和细菌纳米纤维素,以及3种纳米纤维素的特性及其主要制备方法;重点介绍了纳米纤维素在食品领域的应用,主要包括其作为食品添加剂、功能性食品成分及食品包装材料等其他用途,并对其未来发展进行展望。