Cellulose最新文献

Biomass-derived substrates have high porosities and hydrophilic properties that match the requirements as substrate in a heat localization solar steam generation (SSG) system. Nevertheless, the irregular branched pattern of the pore structure hinders water flow from bottom to top to immediately replace the evaporating water. Here we report a method to align fiber orientation of cellulose aerogel derived from coir fiber by an electro-assisted method. Specifically, an electric field was applied during the initial phase of gelation process during cellulose aerogel preparation using the dissolution-coagulation route. The vertically aligned fibers in the electro-assisted cellulose aerogel result in higher thermal conductivity (0.246 W m⁻¹ K⁻¹) due to a shorter path of solid for heat flow, smaller thermal tortuosity, than that of the unaligned fibers (0.011 W m⁻¹ K⁻¹). Moreover, they also provide a shorter path of water flow, which is indicated by the higher hydraulic conductivity and the higher water pumping capacity. When used as the substrate for bilayer heat localization SSG system by depositing magnetite nanoparticles as the photothermal material, the vertical and unidirectional fibers can quickly replace the evaporating water resulting in high solar evaporation rate of 1.178 Kg m⁻² h⁻¹ under 1 sun irradiation. The electro-assisted cellulose aerogel appears promising as a sustainable and excellent substrate for bilayer SSG system in solar-driven water purification to supply clean water from seawater.

Gradiently denitrated gun propellant (GDGP) prepared from nitrocellulose-based propellant by denitration strategy has the advantages of high combustion progressivity and storage stability, but still presents the problems of difficult ignition and lower oxygen balance than that of the raw propellant. In addition, the low utilization efficiency of uniformly added ablation inhibitors in conventional propellant formulations can also lead to harmful shooting phenomena. In this paper, nano-zinc oxide (ZnO) with high thermal conductivity as one of the ablation inhibitors was loaded on the surface of GDGP for the first time. FTIR, Raman, XRD, SEM, and XPS characterizations confirmed the preparation and structural integrity of the GDGP and gradiently denitrated gun propellant-ZnO composite (GDGP@ZnO) with ZnO in nano-size and adjustable loading concentration. The test results showed that GDGP@ZnO exhibited higher combustion progressivity than raw propellant, and the appropriate loading concentration of ZnO could enhance the heat conduction across the surface of the gun propellant and improve the ignition performance. The ablation inhibitor loaded on the surface of the gun propellant can provide an ablation inhibition effect while reducing the dosage. This work provides a new idea for the design and fabrication of a novel multifunctional integrated gun propellant with high combustion progressivity, easy ignition and low ablation.

High bulk papers are attractive because they use less pulp but achieve properties suitable for applications in tissue, filters, and lightweight packaging. This study explores using hydroxypropyl methylcellulose (HPMC), a low-cost and renewably-sourced cellulose derivative, as a surface modifier for mechanical pulps to enhance paper properties. Two application methods were investigated: (1) pre-treatment by adding HPMC to the pulp dispersion and (2) post-treatment by spraying HPMC solution onto paper. Both pre- and post-treated handsheets exhibited improved tensile index and bulk concurrently, which is rarely observed. HPMC adsorbed to the fibre surface spontaneously improving fibre–fibre bonds through polymer entanglement, which led to higher tensile properties. Higher bulk values resulted from preventing fibre collapse during drying (i.e., maintaining open fibre lumens), attributed to the surface activity of HPMC and reinforcement of the fibre cell wall (supported by reduced kinks and curl index upon HPMC adsorption). X-ray tomography showed non-collapsed fibres and symmetric structures in handsheets from fibres pre-treated with HPMC, also suggesting improved cell wall strength and fibres that resisted pressure gradients. These findings indicate that HPMC as a paper additive is a practical and sustainable approach to reinforcing paper products, offering an alternative to high energy refining and oxidizing agents. This approach challenges the traditional trade-off between tensile index and bulk in pulp refining, emphasizing the potential of HPMC as a “green” surface modifier to enhance the strength of bulky papers.

Microcrystalline cellulose was subjected to acetylation by different agents in solvent mixtures, composed of the ionic liquids (ILs) 1-butyl-3-methylimidazolium X (X = acetate, BuMeImAcO; chloride, BuMeImCl), and the molecular solvents (MSs), N,N-dimethylacetamide (DMAc) and dimethyl sulfoxide (DMSO). The reactions were carried out under homogeneous conditions using the following acetylation agents: acetic anhydride ((Ac)₂O), 1-acetyl-3-methylimidazolium acetate (AcMeImAcO), and vinyl acetate (VA). The efficiency of acetylation was judged by the degree of biopolymer substitution, DS. For all binary solvent mixtures, the order of DS was: AcMeImAcO > (Ac)₂O > VA. For the same acetylating agent, the order of DS was: BuMeImAcO-DMSO > BuMeImAcO-DMAc > BuMeImCl-DMSO. We rationalize this dependence of DS on reaction conditions by considering our experimental data and the results of molecular dynamics simulations (MD). Thus, solvent-induced separation of cellulose chains leads to higher acetylation rates, hence larger DS values. The order of biopolymer dissolution/chain separation is attributed to a combination of hydrogen-bonding of the IL anion with cellulose hydroxyl groups, and biopolymer-solvent hydrophobic interactions. The results of MD simulations showed an additional important point: the compositions of the cellulose solvation layers are different from those of bulk solvent mixtures; they are richer in IL ions; this difference affects the values of DS. Thus, theoretical calculations help in choosing the best solvents for cellulose dissolution/derivatization.

Spun-dyed lyocell fibers were prepared by mixing cellulose pulp with an indigo dye dispersion and subsequent spinning. The indigo dye dispersion was obtained by adding leuco indigo to N-methylmorpholine-N-oxide (NMMO) solution. The particle size of the indigo dye was controlled by adjusting the dispersion conditions. Furthermore, the application of ball milling resulted in a reduced average dye particle size of 222.3 nm. The structure and properties of the fibers were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and strength testing. Indigo dye particles were distributed in the interior and surface of the fibers. Relative to the undyed fiber, the crystal structure of the colored fibers was unchanged, but the crystallinity and mechanical properties improved. The color strength and color fastness of the spun-dyed lyocell fibers were assessed according to industry standards. Increasing the dye content and reducing the dye particle size (via ball milling) increased the color strength of the fibers, and the color fastness to sun and soap washing was high (Gray card grade 5). Additionally, the dye did not diffuse into the spinning coagulation bath and thus did not affect the recovery of NMMO solvent. The present study demonstrates a viable strategy for preparing spun-dyed lyocell fibers.

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Ramie fibers have poor flame-retardant properties, which limits their application. To improve the flame-retardant properties of ramie fabric (RF), a durable flame-retardant coating was successfully realized on RF by combining covalent bonding and electrostatic adsorption. Si/P/N flame-retardant coatings were constructed on RF using cationic polyethyleneimine (PEI) and anionic sodium hexametaphosphate (PSP) via the layer-by-layer (LBL) assembly approach with the introduction of 3-glycidoxypropyltrimethoxysilane (GPTMS) as an organic cross-linker. Compared with the untreated RF samples, the fabrics treated with the flame-retardant coating PEI/PSP via the LBL method presented reductions of 51.06%, 48.30%, and 40.05% in the fire growth rate, peak heat release rate, and total heat release, respectively, in the cone calorimeter test. In addition, at a weight gain of 31.57%, the fabric self-extinguished in the UL-94 test within 10 s after leaving the ignition source, resulting in a damaged length of 6.13 cm. G-3 retained the limiting oxygen index (LOI) of 26.40% after 6 laundering cycles (LCs). The TG results revealed that the char residue of G-3 at 800 °C reached 30.34 wt%. The surface of the flame-retardant coating of GPTMS-PEI/PSP had good char formation. This study provides a feasible method for realizing durable flame-retardant RFs.

There is a need for sustainable and eco-friendly materials to drive innovation in the ever-evolving paper industry in producing high-quality paper. Conventional approaches use woody fibers for their better paper-forming properties and strength. However, with an increase in population and a ban on single-use plastics, a need exists to produce more paper at economical prices. This research aims to minimize the use of woody fibers in papermaking by blending miscanthus (non-woody) pulp in eucalyptus (woody) pulp, thereby achieving similar paper properties as virgin pulp. Cationic starch and sodium alginate were electrostatically deposited on fibers to enhance the strength of the paper produced. The addition of cationic starch and sodium alginate increased the water retention value while the freeness in terms of °SR remained constant. The Fourier-transform infrared spectroscopy confirmed the presence of cationic starch and alginate which reduced the carboxyl peaks on bonding with hydroxyl groups of cellulose fibers. The developed paper sheets made from pulp blend after adding cationic starch and alginate were more remarkable than those made from virgin eucalyptus pulp in terms of mechanical properties, justifying their application in the packaging sector. Moreover, the handsheets were completely recyclable without any micro-stickies or flocs. The developed paper can be a sustainable and cost-effective alternative for reducing the utilization of wood fibers in papermaking.

The anionic nature of both cellulose fibres and reactive dyes prevents substantial exhaustion of dye from the dyebath, which is at neutral pH before alkali is added to initiate dye fixation. Conventionally, salt is added to minimize the electrostatic repulsions that interfere with dye sorption, but that increases salt loads in effluents. An alternative is to affix cationic agents on the cellulose to overcome the inherent anionic charge, but that has generally been observed to result in uneven dye sorption. The focus of investigations in this work is to examine the influence of the ratio of charges on cellulose (of affixed cationic charges to inherent anionic charges) on the extents and evenness of dye sorption. The cationisation agent 3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride (CHPTAC) was grafted on loose viscose fibres to yield 12 to 185 mmol kg⁻¹ cationic group content on the fibre that exhibited an inherent carboxyl group content of 68 mmol kg⁻¹. Three different dyes (of varying molecular sizes and anionic group content) were employed for examination of sorption profiles. The results from both zeta potential measurements and dye sorption profiles showed evidence of limited dye uptake until the cationic group content in fibres exceeded that of the inherent carboxyl groups. Thereafter, an uptick in dye sorption was observed, with dye sorption levels increasing with rise in degree of cationisation. There were differences between the dyes in their degrees of sorption, which appear correlated with their molecular sizes.

In recent years, wearable smart textiles with multifunctional properties have attracted great interest for use with a wide range of applications, including personal protection, sport, healthcare etc. In the present study, all-in-one multifunctional conductive hydrophobic coated cotton fabric with electromagnetic interference (EMI) shielding, joule heating, and antibacterial properties was prepared via in-situ chemical oxidative polymerization. A graphene oxide (GO)–polyaniline (PANI)–silver (Ag) composite was coated onto the cotton fabric, exhibiting a low electrical resistance of 24.3 Ω sq⁻¹ and strong hydrophobicity, with a water contact angle of ~ 139°. The high electrical conductivity of the composite coating resulted in excellent EMI shielding of ~ 52 dB in the X-band frequency region. Notably, the EMI shielding performance was tunable by simply changing the pH due to the acid- and alkali-sensitive nature of PANI. Furthermore, the fabricated conductive cotton fabric demonstrated excellent joule heating, achieving a temperature of 105.7 °C within 30 s at a voltage of 3.5 V. Additionally, in the presence of Ag, the cotton fabric exhibited excellent anti-bacterial properties against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria.

The versatile applications of cellulose nanomaterials derived from natural sources that possess desirable physicochemical properties have garnered significant interest across various disciplines. This contribution focuses on cellulose nanoparticles, which exhibit considerable potential for various biomedical applications, including drug delivery and tissue regeneration, as well as interfacial applications such as catalysis. The ability to modify the surface properties of these nanoparticles by the application of specific and functional groups significantly broadens the range of potential biological applications, with a particular emphasis on cancer treatment. These functionalized nanoparticles exhibit desirable biocompatibility and possess the capability to control biodistribution patterns and are therefore highly appropriate for the advancement of innovative treatment strategies. We review anticancer applications from 2020 to 2024 of these cellulose nanoparticles from a structure-property-function perspective brought out by chemical modifications on the backbone of cellulose structure through various approaches, like carboxymethylation, oxidation, hydroxy propylation, amination reactions, nanogels, and so on. We also pay special attention to a much-overlooked aspect of understanding the interaction of these cellulose nanoparticles in cancerous cells through in vitro methods like MTT assay, western blotting, etc., and in vivo methods.