Cellulose最新文献

Researchers have turned their attention to the potential of lignocellulosic fibre-reinforced composites for various applications. This fibre can take different forms, such as short fibres, long fibres, woven mats, non-woven mats and fabrics. Each form has different properties. This study evaluates the physical, mechanical, dynamic mechanical and thermal properties of woven kenaf (WK) and kenaf/cotton (KC) reinforced bio-epoxy composites. The composites were fabricated using a hand lay-up technique and cured with a hot press. The obtained results show that woven kenaf composites with a 40% fibre loading (WK-FL40: 1.26 g.cm⁻³) have the highest density, while kenaf/cotton composites (KC-FL35: 8.03%) have the highest void content. Additionally, kenaf/cotton composites exhibit higher water absorption than woven kenaf composites. Under saturated conditions, the highest water absorption is shown by KC-FL40, which is 13.8%. Kenaf/cotton composites have superior mechanical properties correlated to woven kenaf composites, where the best overall mechanical properties are shown by composites KC-FL40 (Tensile strength: 117.95 MPa, Tensile Modulus: 11.23 GPa, Flexural Strength: 154.25 MPa, Flexural Modulus: 9.72 MPa, Impact Strength: 10.42 J/m²). The dynamic mechanical analysis reveals that the storage modulus and peak loss modulus increase with fibre loading, while the tan delta peak decreases with addition of reinforcement. In terms of thermal stability, the incorporation of woven kenaf and kenaf cotton fabric slightly improves thermal stability, with the highest residue at 700 °C shown by composites KC-FL30, which is 20.35. Overall, it can be concluded that kenaf/cotton composites have better overall properties compared to woven kenaf composites. They can be used for various indoor applications, such as food trays for aeroplanes.

In this study, the multi-objective optimization of selected mechanical properties of polyester composite plates, produced using hemp and jute fibers in the same structure, were investigated using the Taguchi-TOPSIS method. Hemp and jute natural fibers were incorporated at weight ratios of 30%, 50%, and 70%, with two different arrangements and two surface modification treatments applied to reinforce the composites. Polyester resin was used as the matrix material. Taguchi L18 mixed 2–3 level orthogonal experimental design was employed in the experimental plan. The selected mechanical properties included impact strength, flexural modulus, flexural strength, tensile modulus, and tensile strength. In the study, the optimum levels of the factors corresponding to the best mechanical properties were identified, and the optimal composite plate was determined. The resulting composite was a fiber-reinforced polyester composite treated with 3% NaOH, arranged in a Jute/Hemp/Hemp/Jute layer sequence, with a total fiber weight ratio of 30%. The mechanical properties of this composite were as follows: impact strength of 2.1 kJ/m², flexural strength of 55.17 MPa, flexural modulus 2.75 GPa, tensile strength of 29.06 MPa and tensile modulus 733.56 MPa. The SEM images showed that 3% NaOH application provided effective bonding at the fiber-matrix interface and preserved the structural integrity of the fibers.

In this work, an integrated strategy was proposed for preparing hydrogel based on acrylic acid (AA) and sodium alginate (SA) by adding TEMPO-oxidized cellulose nanocrystals (TOCNs) with different carboxylic groups (–COOH) contents. The addition of TOCNs and increase of its contents in poly(acrylic acid) (PAA)/SA hydrogel systems played a multifunctional role by which the mechanical properties and ionic conductivity of PAA/SA hydrogels were significantly affected and enhanced. TOCNs with their abundant –COOH groups disperses SA and AA in the hydrogel precursor solution for forming a uniform semi-interpenetrating network. It also provides more hydrogen bonds with SA and AA, and results in high modulus of the final hydrogel. Accordingly, the as-prepared hydrogels showed simultaneous good compressive (1.41 MPa at compressive strain of 70%) and tensile (365 kPa strength at fracture strain of 628%) stresses, excellent swelling rate (2509%), good transparency (86.3%) and conductivity (0.229 S m⁻¹). The work confirmed the important roles of –COOH in the TOCNs played in the construction and properties of the hydrogel, and the hydrogels may find great potential applications in the fields of flexible wearable sensors benefits by excellent natural biocompatibility from all the raw materials used.

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Carboxycellulose nanocrystals (CNCs-COOH) have great potential for applications in areas such as food packaging and pharmaceuticals. In this paper, a modified potassium permanganate (KMnO₄) oxidation method was developed, in which disodium dihydrogen pyrophosphate (Na₂H₂P₂O₇) was introduced into the potassium permanganate, and Na₂H₂P₂O₇ was able to complex with Mn³⁺ to form [Mn(H₂P₂O₇)²⁻]⁺, which prevented Mn³⁺ from being reduced, and the oxidative ability of the system was significantly improved, so that the CNCs-COOH was obtained with a high yield, a high crystallinity, and a higher content of carboxylic acid in a mild condition. The effect of Na₂H₂P₂O₇ on the microstructure, chemical and thermal properties of CNCs-COOH was analysed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TGA) and zeta potential. The results showed that the introduction of Na₂H₂P₂O₇ could accelerate the extraction of CNCs-COOH. The preparation method has the advantages of rapidity and high efficiency, which provides a feasible way for the industrial preparation of CNCs-COOH.

This study explored the creation of sustainable biocomposite films. It used the polyvinyl alcohol (PVA) reinforced with chitin (CH) extracted from shrimp shells and microcrystalline cellulose (MCC) extracted from alfa fibers (Stipa tenacissima). Both raw materials are renewable and biodegradable, offering potential for reducing dependence on petroleum-based plastics. These biocomposites feature semi-crystalline structures and strong intermolecular interactions, which indicate an effective molecular-level compatibility. MCC played a key role in improving morphological uniformity. It reinforced interfacial adhesion and created a tighter matrix. Thermal analysis revealed that CH enhances thermal stability. MCC amplifies this effect by decreasing thermal weight loss through enhanced interfacial interactions. UV–Vis spectroscopy demonstrated that CH substantially improves UV-blocking abilities, with MCC contributing to creating a more effective barrier effect. The addition of CH and MCC led to a significant drop in water absorption. Also, water contact angle measurements confirmed that surface hydrophobicity increased. Mechanical testing revealed notable enhancements in tensile strength, Young’s modulus, and elongation at break. The composites containing 50% and 30% chitin, with 10% MCC in the PVA matrix, demonstrated the best overall performance. These findings highlight the potential of CH and MCC as functional reinforcements for sustainable, high-performance biocomposite materials.

The research investigates the mechanical and thermal properties of hybrid date palm/glass fiber-reinforced composites with varying date palm fiber lengths. The study is motivated by the increasing interest in sustainable, eco-friendly composites incorporating natural fibers. For this purpose, treated date palm fibers (D2, D20, and UD fibers) were used as natural fiber reinforcement, and the composite samples were fabricated using hand lay-up combined with the vacuum-assisted hot press technique. Date palm/glass hybrid composites were characterized by various mechanical tests such as tensile, flexural, and impact testing. UD-glass exhibited a maximum tensile strength of 160.4 MPa, which is approximately 30.7 and 34.4% higher than those of D2-glass (122.7 MPa) and D20-glass (119.3 MPa), respectively. Furthermore, UD-glass indicated a maximum flexural strength of 646.9 MPa, representing an increase of 57.3% over D2-glass (411.4 MPa) and 114.5% over D20-glass (301.6 MPa). Additionally, UD-glass demonstrated the highest impact strength (402 J/m), which is 16.1% higher than D2-glass (346.2 J/m) and 6.8% more than D20-glass (376.4 J/m). The thermal properties of the hybrid composites were analyzed using thermogravimetric analysis (TGA). UD-glass exhibited the highest value of thermal stability at 372.6 °C, indicating enhanced resistance to thermal degradation due to the unidirectional fiber arrangement. Results showed that UD fibers provided the best mechanical properties and highest resistance to thermal degradation. SEM analysis confirmed improved fiber-matrix interaction in composites with longer, aligned fibers.

Bacterial cellulose is a sustainable substitute for synthetic polymers. In this study, 50 bacterial isolates from the soil rhizosphere of indigenous black rice plants were screened for cellulose production. Among these, Enterobacter mori R45 had the most potent ability in cellulose synthesis. White rice straw and black rice straw were investigated as substrates for bacterial cellulose production. A comparative assessment was performed between the standard media and the two modified media containing white rice and black rice straw hydrolysates. The culture parameters of the modified media were optimised using the Taguchi design. White rice straw media gave a maximum yield of 2.48 g/L, followed by black rice straw media (0.93 g/L), which were again higher than standard media, i.e. 0.54 g/L. The higher cellulose yield in the white rice straw media was due to the absence of anthocyanin and the lower phenolic content than in black rice straw media. SEM images showed dense and compact crystalline cellulosic particles in the products of modified media. The FTIR spectra showed the characteristic functional groups of cellulose in all the samples. The crystallinity index (CI) of cellulose produced in standard HS medium was 91.62%, followed by 91.46% in white rice straw (WRS) medium and 88.03% in black rice straw (BRS) medium. The cellulose obtained using white rice straw hydrolysates in the medium was found to be the highest in terms of production yield and thermal stability. This medium could be a potential substrate for microbial cellulose production.

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Customized superabsorbent hydrogels are of significant interest across several fields of science and engineering due to their practical applications. A conventional classification of hydrogels is based on their composition, in which an ion is attached to the polymeric chain, with commercially available hydrogels typically containing of sodium ions. This composition opens the possibility of developing a less explored type of hydrogel based on potassium, which is strategic due to its role as an essential nutrient for both plant and animal life. This enable more beneficial integration into the environment or interaction with various organisms. These aspects contrast with sodium-based hydrogels, which, although more widely used commercially, may pose environmental and biological concerns, including potential toxicity, degradation of soil structure, and health risks such as hypertension and cardiovascular disorders. This study systematically examines the effects of cellulose nanocrystal (CNC) incorporation on the physicochemical properties of potassium polyacrylate-based polymeric hydrogels. Through controlled variation of CNC loading concentrations, we characterize the structure‐property relationships governing hydrogel performance. These polymeric materials were synthesized in an aqueous medium using a free radical technique and subsequently processed through drying, grinding, molding, lyophilization, and electrospinning, resulting in different forms of hydrogel presentations. The materials were characterized using cyclic swelling and deswelling tests, contact angle measurements, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and optical microscopy. The results demonstrated that CNC content directly tuned key properties: FTIR/EDS confirmed CNC integration, swelling tests revealed adjustable absorption capacity, and SEM showed microstructure control in several presentations (films, electrospun mats, particles). These findings highlight the hydrogel’s customizable functionalities—swelling, and deswelling and contact angle—for requests where eco-compatibility and nutrient synergy are critical, advancing the design of adaptive, sustainable hydrogel systems.

Organic pollutants such as dyes, nitro compounds, and halogenated substances are highly toxic, persistent, and often resistant to natural degradation. Therefore, the development of cost-effective, reusable, and environmentally friendly catalysts for the mitigation of organic pollutants is both urgent and essential. This article presents a comprehensive overview of cellulose-supported 3d-transition metal nanocatalysts developed for environmental remediation, focusing on their synthesis, efficiency, and reusability in the degradation of hazardous organic pollutants. It highlights the use of cellulose-based supports, such as carboxymethyl cellulose and cellulose acetate, to enhance the stability and catalytic performance of metal nanostructures, including Fe, Co, Ni, Cu, and bimetallic combinations like Ni–Fe and Cu-Fe. The catalysts demonstrated significant efficacy in reducing toxic compounds like various nitrophenols, dyes, and organohalides, and pharmaceuticals, achieving high reduction rates and maintaining activity across multiple recycling cycles. The document also discusses the kinetics of these reactions, emphasizing pseudo-first-order behavior, and the impact of various parameters such as temperature, pH, and catalyst composition on performance. Additionally, it explores the mechanisms underlying the catalytic processes, including electron transfer and the role of reducing agents. Overall, this work underscores the potential of cellulose-supported nanocatalysts as effective and sustainable solutions for mitigating environmental pollution.

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This study investigated the enhancement of carboxymethyl cellulose (CMC)-based films through the incorporation of gelatin and alkyl ketene dimer (AKD), aiming to address inherent limitations in hydrophobicity, film-forming capability, and mechanical strength. To further optimize film properties, three plasticizers, citric acid, glycerol, and isosorbide, were systematically evaluated for their effects on film morphology and flexibility. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses revealed extensive hydrogen bonding among CMC, gelatin, and AKD, evidenced by a marked reduction in free hydroxy groups, indicative of strong intermolecular interactions. Thermal and morphological characterizations further demonstrated that isosorbide promoted homogeneous film formation, while AKD increased surface roughness and improved water resistance. Among all tested formulations, the CMC–gelatin film incorporated with isosorbide and AKD (SCGI–AKD film) exhibited the most favorable hydrophobic performance, achieving a contact angle (CA) of 105.09°, a water solubility (WS) of 28.46%, and a reduced water vapor permeability (WVP) of 0.65 g m/m² s Pa. This formulation also displayed superior mechanical characteristics, including a tensile strength of 13.27 MPa, a Young’s modulus of 151.24 MPa, and an elongation at break of 38.71%. Optical measurements confirmed the compatibility of composite components, as all films maintained stable visible light transmittance. Notably, the SCGI–AKD film exhibited selective light-filtering capacity, transmitting only 29.59% for UV light at 300 nm while allowing 80.25% transmittance at 600 nm in the visible range. These findings underscore the potential of CMC–gelatin–AKD composite systems as sustainable, multifunctional packaging materials with tunable barrier, mechanical, and optical properties.

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Synopsis: The synergistic incorporation of AKD and isosorbide into CMC films significantly enhanced hydrophobicity, film-forming capability, and mechanical performance, underscoring their potential for application in sustainable packaging systems.