Cellulose-based Antimicrobial Composites and Applications: A Brief Review

Cellulose-based antimicrobial composites, typically in the form of functional films and cloth, have received much attention in various applications, such as food, medical and textile industries. Cellulose is a natural polymer, and is highly biodegradable, green, and sustainable. Imparting antimicrobial properties to cellulose, will significantly enhance its applications so that its commercial value can be boosted. In this review paper, the use of cellulose for antimicrobial composites’ preparation was discussed. Two different approaches: surface loading/coating and interior embedding, were focused. Three most widely-applied sectors: food, medical and textile industries, were highlighted. Nanocellulose, as a leading-edge cellulose material, its unique application on the antimicrobial composites, was particularly discussed.     

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.     

Application of meta-analysis in the field of costume studies北大核心CSCD

With the development of the methodology of research review, meta-analysis has been widely applied in the study of various disciplines.However, through literature collection and combing, it is found that the application of meta¬analysis in the field of domestic costume studies is still blank theoretically.To facilitate the extensive use of meta-analysis in domestic integration research on costume theories, and improve the standardization and objectivity of research on costume theories, through an analysis of the basic meaning, functions, advantages, sample selection and research process of meta¬analysis, 52 domestic research papers published from 2(K)7 to 2019 on the relationship between online consume reviews and consumers' purchase intention were taken as examples, to explore the application process of meta-analysis in the field of costume studies in a systematic way and key points thereof.Finally, through literature survey and an analysis of domestic and foreign applications, it is verified that meta-analysis has a good prospect in theoretical studies on costumes in the future. © 2021 China Silk Association. All rights reserved.     

Preparation and Applications of Soybean Residue CNF Films

In this study, soybean residues were treated with HCl and soybean residue cellulose was extracted, which was used to prepare cellulose nanofiber (CNF) using the high-pressure homogenization method. The maximum yield of CNF, the reaction temperature, reaction time, and HCl concentration were optimized. The optimum HCl concentration for acid treatment was 6%, the reaction time was 60 min, the reaction temperature was 80℃, and the maximum yield of soybean residue cellulose was 78.8%. The different CNF films were then prepared; the color, mechanical property, and light transmittance of the CNF films were studied. Compared to the properties of the CNF film prepared with the soybean residue cellulose by high-pressure homogenization 15 times (HGT-15 film), the mechanical properties of the CNF film with soybean residue cellulose by decolorizing treatment decreased, but the light transmittance increased. The film prepared by adding HGT-15 CNF to whey protein was investigated for its mechanical property, light transmittance, and solubility. Unlike the pure whey protein film, addition of 2.0% CNF to the whey protein enhanced the mechanical property and water vapor transmission rate (WVT) of the film. With the increase in CNF content, the solubility of the whey protein film decreased, and then stabilized.     

Effect of Thermal Treatment on the Properties of TEMPO Oxidized Cellulose Film for the Flexible Substrate of Solar Cell

The 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose film (TOCF) has been attempted to be used as a substrate in electronic and optoelectronic devices, but the changes in the TOCF properties before and after annealing treatment have usually been neglected during device fabrication. In this study, TOCF was treated in different atmospheres (air, vacuum, and N₂) and at different temperatures, and the properties were investigated. The results indicate that the optical properties are slightly affected by atmosphere and temperature; only slight transmittance loss and haze increase have been observed when TOCF is exposed to an air atmosphere at temperatures of above 120℃. In contrast to the slight effects on the optical properties, cellulose degradation and a loss of film strength have been observed regardless of the atmosphere used when placed at temperatures of above 100℃. Specifically, TOCF was exposed to air, followed by N₂ and vacuum atmospheres. Additional Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) results showed that increasing the temperature had no significant effect on the structure of TOCF. Therefore, the annealing temperature should be controlled at a temperature of lower than 100℃ and a vacuum atmosphere is preferred.     

Research progress on chemical modification of silk fibroin and its applications北大核心CSCD

Mulberry silk is composed of the two major parts of two triangle-like silk fibroin fibers and sericin covering the fibers and a few lipids. After removing the sericin on the raw silk what is left is the silk fibroin fiber. Silk fibroin is the main part of silk accounting for about 75% of the total weight. Silk fibroin contains 18 natural amino acids such as glycine Gly alanine Ala serine Ser serine aspartic acid Asp and tyrosine Tyr . The secondary structure of silk fibroin has three main conformations α-helix β-fold and random coil. Under certain conditions the three conformations can transform into each other and change the mechanical properties of the silk fibroin material. Silk fibroin extracted from silk fiber is a natural polymer with biocompatibility and biodegradability. It can be further processed into different forms of materials nanoparticles films hydrogels sponges etc. It has been applied in many fields such as biomedicine and cosmetics. In order to meet the needs of different fields researchers have conducted further chemical modification treatment based on the original excellent properties of silk fibroin. Meanwhile the active groups on various amino acid residues in silk fibroin also provide chemical reaction sites for the chemical modification of silk fibroin. The chemical modification methods of silk fibroin mainly include amino acid residue modification macromolecular grafting modification and crosslinking reaction modification. Among them amino acid residue modification can modify protein amino acid residues by chemical reagents and some groups can be introduced into the side chains of silk fibroin macromolecules. Grafting modification of silk fibroin macromolecules is one of the main means to bind functional compounds to silk fibroin macromolecular chains. The properties of grafted silk fibroin are affected by the type and grafting rate of the grafts. The chemical crosslinking reaction modification of silk fibroin macromolecules is to make the macromolecular chains connected by covalent bonds and form a network structure by means of crosslinking agents enzymes or ultraviolet irradiation. The cross-linking reaction can not only form covalent bonds within and between the molecular chains of silk fibroin thus changing its structural properties and improving its stability but be used to form covalent bonds with other polymers. At present the chemical modification of silk fibroin is mainly applied in the fields of silk textiles biomedicine and environmental science. In the field of silk textiles graft copolymerization modification of vinyl and other monomers crosslinking agent modification and other methods are used to overcome the shortcomings of silk like being easy to wrinkle. The graft modified monomers mainly include ethylene methacrylate and methylacrylamide. The active groups on crosslinking agents such as polycarboxylic acid / anhydride and epoxide are covalently combined with carboxyl hydroxyl and amino groups on macromolecules of silk fibroin to improve the wrinkle resistance of silk fabrics. In the field of biomedicine silk fibroin materials with appropriate chemical modification have better biological activity drug delivery ability antimicrobial properties and mechanical properties. The optimization of these properties enables silk fibroin materials to show great potential in drug control delivery tissue regeneration and wound repair. The applied research in the field of environmental science mainly focuses on the adsorption separation and catalysis of impurities in water. Therefore the modification of amino acid residues grafting and cross-linking of protein macromolecules can change some important properties of silk fibroin and meet the requirements of various applications and functionalization of silk fibroin. In many fields of chemical modification and application of silk fibroin protein fruitful results have been achieved which has laid a good foundation for the further development of related fields and also shows that the chemical modification of silk fibroin material has great potential and application prospects. However there are still some problems that need to be overcome and further improved in the current chemical modification methods such as mild modification conditions and accurate adjustment of the degree of modification which will be the research direction of related fields in the future. © 2022 Authors. All rights reserved.     

Pore Structure Regulation of Carboxyethylated Microfibrillated Cellulose Films

Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose(MFC).The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties.In order to expand its application,three approaches including using organic solvents,different drying methods and cationic additives,have been adopted in this paper to enrich and regulate the pore structure of MFC film.The results show that all the approaches can improve the pore structure but decrease the mechanical properties of MFC film.When organic solvents such as ethanol,isopropanol and n-butanol were used to replace the water in MFC suspension or pre-dried MFC film,the pore structure of films were increased.Additionally,the film obtained by freeze-drying or air-drying after freezing in liquid nitrogen or freezer has high porosity but poor strength.The best drying process is to rewet dry MFC film,freeze in liquid nitrogen and then freeze-dry.Moreover,the addition of cationic polyelectrolytes or alkene ketone dimer(AKD)in MFC suspension can also significantly increase the film's porosity.Through the above approaches,the porosity of carboxyethylated MFC film can be regulated between 20% and 90%.     

Green and Effective Ammonium Carbonate-assisted Process for Drying Hemicellulose Obtained through Alkali Extraction of Bleached Bamboo Kraft Pulp

Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually present as a spent liquor,such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers.Due to its dilute nature,hemicellulose needs to be dried for practical utilization,and this is challenging.In this study,cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process.Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process.The effects of drying time and drying temperature were determined.Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose,as revealed by detailed Fourier transform infrared and X-ray diffraction analyses.The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method,and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose.The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.     

One-step Fabrication of Cellulose/Graphene Conductive Paper

In this study,a straightforward,one-step wet-end formation process was employed to prepare cellulose/graphene conductive paper for antistatic packing materials.Cationic polyacrylamide was introduced into the cellulose/graphene slurry to improve the graphene loading on the surfaces of the cellulose fibers.The effect of the super calender process on the properties of the cellulose/graphene conductive paper was investigated.When 55 wt% graphene was added,the volume resistivity of the cellulose/graphene conductive paper was 94.70 W·cm,decreasing to 35.46 W·cm after the super calender process.The cellulose/graphene conductive paper possessed excellent anti-static ability and could be used as an anti-static material.     

Biomass-derived Porous Carbon Materials for Supercapacitor Electrodes:A Review

The development of renewable,cost-efficient,and environmentally friendly electrode materials with excellent performance is urgently needed for improving supercapacitors(SCs).Recently,biomass-derived porous carbons(BPCs)have received increasing attention due to their excellent physical and chemical properties,widespread availability,and low production cost.In this review,the progress in preparing BPCs and the properties of prepared BPCs are presented and discussed.In addition,the applications of BPCs as electrode materials for supercapacitors are also summarized.More importantly,the pore structure and surface properties of BPCs are all determining factors to improve electrochemical performance.Moreover,a high energy density and power density can be pursued by using composites based on BPCs as electrode materials,of which combining transition metallic oxide with BPCs is one of the most attractive selections.Therefore,rational design of BPCs with respect to the supercapacitor's performance should be conducted in the future.     

Simultaneous Extraction of Carboxylated Celulose Nanocrystals and Nanofibrils via Citric Acid Hydrolysis——A 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.     

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.     

纤维素纳米纤丝基水凝胶及其在废水处理中的应用进展

纤维素纳米纤丝(CNF)作为一种来源丰富的可再生纳米材料,具有优异的机械性能、高比表面积及化学可修饰性等优点,采用物理或化学交联所制备的CNF基水凝胶具有较好的机械性能和溶胀率等,在工业废水处理领域具有良好的应用前景。本文主要介绍了纯CNF水凝胶和CNF纳米复合水凝胶的相应制备方法及性能,同时也介绍了其在工业废水中对染料或重金属离子吸附方面的应用进展,最后指出了CNF基水凝胶在废水处理应用中存在的问题及未来主要研究方向。     

亚麻分层纳米纤维素的制备及其增强热电复合材料性能

为从天然亚麻纤维中制备出分层纳米纤维素(即纤维素纳米纤维(CNF)与纤维素纳米晶(CNC)共存),并对其制备方法进行优化完善,提出将亚麻纤维在特定浓度的氢氧化钠溶液中碱化处理后,再进行四甲基哌啶氮氧化物(TEMPO)介导的三元氧化和机械处理的联合处理方法。然后将亚麻CNF与石墨烯复合制备CNF/石墨烯复合薄膜并研究亚麻CNF增强热电复合材料的性能。结果表明:碱化预处理使亚麻纤维直径变细,长度变短,半纤维素被脱除,是生成不同尺寸CNF的重要步骤;随着氢氧化钠用量在0~18%范围内的增加,所得CNF悬浮液的光透过率从3.7%增加到95.1%;CNF/石墨烯复合膜表现出最高功率因子,为8.0×10 ^-3 μW/(m·K ²),表明复合薄膜具有热电性能。     

碳纤维特性及其在功能纸中的应用

概述了碳纤维的形成及物理、化学性能,重点介绍了碳纤维在造纸工艺中的分散性能,打浆性能和成纸结合性能,及其在导电纸、发热纸、屏蔽纸等功能纸中的应用。     

纤维素纳米纤丝在生物质基3D打印材料中的应用研究

本文综述了近年来纤维素纳米纤丝(CNF)及其相关的复合材料用作生物质基3D打印材料在医学、纺织品、食品、导电材料、智能材料等几个热门领域中的应用研究进展,以及CNF在生物质基3D打印材料中的作用与功能。最后,对CNF作为一种多功能的纳米材料在生物质基3D打印技术中的应用前景做了展望。     

Nanocellulose Reinforced Chitosan Composite Films as Affected by Nanofiller Loading and Plasticizer Content

ABSTRACT: Chitosan is a biopolymer obtained by N-deacetylation of chitin, produced from shellfish waste, which may be employed to elaborate edible films or coatings to enhance shelf life of food products. This study was conducted to evaluate the effect of different concentrations of nanofiller (cellulose nanofibers, CNF) and plasticizer (glycerol) on tensile properties (tensile strength—TS, elongation at break—EB, and Young's modulus—YM), water vapor permeability (WVP), and glass transition temperature (T_g) of chitosan edible films, and to establish a formulation to optimize their properties. The experiment was conducted according to a central composite design, with 2 variables: CNF (0 to 20 g/100 g) and glycerol (0 to 30 g/100 g) concentrations in the film (on a dry basis), which was produced by the so-called casting technique. Most responses (except by EB) were favored by high CNF concentrations and low glycerol contents. The optimization was based on maximizing TS, YM, and T_g, and decreasing WVP, while maintaining a minimum acceptable EB of 10%. The optimum conditions were defined as: glycerol concentration, 18 g/100 g; and CNF concentration, 15 g/100 g. AFM imaging of films suggested good dispersion of the CNF and good CNF-matrix interactions, which explains the good performance of the nanocomposite films. Practical Application: Chitosan is a biodegradable polymer which may be used to elaborate edible films or coatings to enhance shelf life of foods. This study demonstrates how cellulose nanofibers (CNF) can improve the mechanical and water vapor barrier properties of chitosan films. A nanocomposite film with 15% CNF and plasticized with 18% glycerol was comparable to some synthetic polymers in terms of strength and stiffness, but with poorer elongation and water vapor barrier, indicating that they can be used for applications that do not require high flexibility and/or water vapor barrier. The more important advantage of such films when compared to synthetic polymer films is their environmentally friendly properties.     

离子液体在生物质分离与转化中的应用前景

离子液体作为一类新型的环境友好的＂绿色溶剂＂,具有很多独特的性质,在很多领域有着诱人的应用前景。本文简单介绍了离子液体的发展和特点,对离子液体在纤维素溶解、生物质分离与转化、制浆造纸中的应用及前景做了详细的综述。     

Preparation and Characterization of Co3O4/Graphene/Cellulose Nanofiber Composite Films

Nanocellulose has served as an eye-catching nanomaterial for constructing advanced functional devices with renewability, light weight, flexibility, and environmental friendliness. In this study, Co₃O₄/graphene/cellulose nanofiber (CNF) flexible composite films, in which the CNF acted as a spacer for the graphene, were prepared via a facile and scalable vacuum filtration method. The effects of the CNF on the microstructure, hydrophilicity, thermal stability, tensile strength, surface resistance, and electrochemical performance of the Co₃O₄/graphene/CNF composite films were systematically investigated. The results showed that the synergistic interaction of the CNF and graphene substantially improved the overall properties of the Co₃O₄/graphene/CNF composite films, particularly their hydrophilicity and tensile strength. Meanwhile, Co₃O₄/graphene/CNF composite films with a CNF content of 4% appeared to have the optimal electrochemical performance, with an area specific capacitance of 56 mF/cm² and prominent capacitance retention of 95.6% at a current density of 1 A/g after 1000 cycles. This work demonstrated that the prepared Co₃O₄/graphene/CNF flexible composite films have great application potential in the field of flexible energy storage devices.     

合成纤维的湿法成形抄造

非植物纤维与传统的植物纤维抄纸存在很大的差别。文章探讨了合成纤维湿法抄造过程中所存在的工程上和流体力学方面的问题及其解决方法。