Cellulose最新文献

High-performance cellulose fibers have attracted significant attention due to their renewability, biocompatibility, and excellent mechanical properties. However, the high viscosity of spinning solutions and the difficulty in achieving uniform dispersion of additives hinder chain alignment and the development of fiber crystallinity. In this study, Fe₃O₄ nanoparticles (NPs) were uniformly dispersed into a cellulose (Cel)/4-( ( ω- ( methylimidazole) hexyloxy) -4 ‘—( cyano) -biphenyl (CBP6)/[AMIMCl] side-chain liquid crystal solution using ultrasound and mechanical stirring. During the dry-jet wet spinning process, a 200 mT axial magnetic field was applied to induce cellulose molecular alignment and produce high-strength fibers. Characterization techniques including torque rheometry, POM, SEM, TEM, XRD, SAXS, VSM, MR, and DSC were employed. Results show that Fe₃O₄ NPs aligned under the magnetic field, enhancing molecular orientation and crystallinity. The Cel/3%CBP6/3%NPs fibers exhibited a breaking strength of 3.30 cN/dtex and an elongation at 13.5%. Notably, the fibers prepared with magnetic field assistance (Cel/CBP6/NPs-M) achieved a significantly higher breaking strength of 3.86 cN/dtex and an elongation of 11.8%, representing a 107.52% increase in strength relative to pure cellulose fibers. XRD analysis confirmed an enhanced crystallinity of 60.69%, while SAXS results indicated improved molecular orientation with a value of orientation of 75.27%. This study highlights that magnetic field-assisted liquid crystal spinning is an effective strategy for enhancing the structure and mechanical performance of cellulose fibers, advancing the development of high-performance bio-based materials.

This study examined the influence of polyhydroxybutyrate grafted maleic anhydride (PHB – g – MA) copolymer on the mechanical, structural, thermal, morphological, and rheological properties of polyhydroxybutyrate (PHB)—cellulose nanocrystal (CNC) nanocomposites. The results showed that the adding PHB – g – MA and CNCs had a positive effect on the mechanical and morphological properties of the BNCs (biopolymer nanocomposites). According to the DSC results, there were slight changes in the crystallization temperature (Tc) and the melting temperature (Tm) of the BNCs, and the DMA curves showed that the inclusion of PHB – g – MA resulted in an increase in the storage and loss moduli. The XRD results showed four main peaks with 2θ values of 13.57°, 16.98°, 22.2°, and 25.39° with the presence of both PHB – g – MA and CNCs. In rheological studies, it was determined that both elastic and viscous moduli of the neat PHB and the BNCs generally increased as the frequency value was raised.

Nanotechnology is used on a large scale in the textile sector to improve fabrics or give them unique functions. Medical textiles used in healthcare settings require enhanced functional properties to protect healthcare workers from pathogenic bacteria and fluid contamination while maintaining comfort and durability. Medical textile products must meet stringent quality standards to ensure safety for both patients and healthcare workers in clinical environments worldwide. Therefore, to achieve certain functional properties like antibacterial and liquid-repellent qualities, silicon dioxide nanoparticles and chitosan nanoparticles were used to treat some knitted fabrics (viscose, lyocell, and viscose/lyocell blends) for use in creating medical gowns for doctors to protect them from the risks posed by bacteria and fluid. The results indicated that the best concentration of silicon dioxide nanoparticles was 3%, which recorded water contact angles of 154.6 ± 1.8 degrees, 155.3 ± 1.5 degrees, and 163.4 ± 1.3 degrees for viscose, viscose/lyocell blends, and lyocell fabrics, respectively. Fabrics treated with a weight concentration of 3% chitosan nanoparticles showed ideal bacterial resistance reaching 98.4 ± 0.5%, 98.7 ± 0.3%, and 99.1 ± 0.4% for gram-positive bacteria and 95.6 ± 0.6%, 96.1 ± 0.4%, and 97.2 ± 0.5% for gram-negative bacteria for viscose, lyocell, viscose/lyocell blends, respectively. This study demonstrates the successful development of multifunctional cellulosic textiles with combined antimicrobial and water-repellent properties for medical applications.

With the depletion of fossil fuels, biomass as a renewable resource is considered as an alternative to fossil fuels. Lignocellulosic biomass (LCB) is a promising renewable resource, and the main components can be used to produce liquid fuels. Fractionating the main components (cellulose, hemicellulose, and lignin) of LCB is the most vital step in the biorefining process due to the complex structure of LCB. Organic solvents, as environmentally friendly, low-cost, and recyclable compounds, can effectively deconstruct LCB. Organic solvent-based pretreatments (OPs) have been widely used to promote the production of fermentable sugars and their conversion rates for green liquid fuels. Herein, we first compared and investigated the current status of the development of OPs of different kinds of organic solvents, including alcohols, organic acids, esters, amines, ketones, aldehydes, and cyclic ethers. The efficiency of fractionation on the three components (cellulose, hemicellulose, and lignin) of OPs and the effects on products of pyrolysis or hydrolysis were systematically summarized. The mechanisms of OPs of different kinds of organic solvents and strategies based on first principles to improve the performance of OPs were summarized. The conversion rates of fermentable sugars to ethanol through fermentation were also summarized. The current challenges and prospects of OPs were presented. This paper aims to assist in the selection and mechanism investigation of OPs for biomass utilization.

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The process of organic solvent-based pretreatments of lignocellulosic biomass for producing liquid fuels

Derivatization holds huge potential for high-value utilization of cellulose by enhancing its processability and functionality. Typically, the cellulose derivatives with outstanding ultraviolet (UV) shielding properties have received great attention. Herein, a feasible method was proposed for efficiently converting regenerated cellulose to cellulose folate ester with exceptional UV shielding properties via esterification with folic acid (FA) in a homogeneous solvation system, where N,N'-dicyclohexylcarbodiimide was employed as a water absorber and 4-dimethylaminopyridine as a catalyst to facilitate the esterification reaction. The finding indicated that increased FA dosage led to enhanced UV shielding performance of cellulose folate ester films (CFEF). Notably, at FA content of 1.0 wt.%, CFEF exhibited a transmittance of 0% in the UV region and a transparency of 86% in the visible region. Moreover, CFEF was found to display superior performance in thermal stability, tensile strength and ductility over regenerated cellulose films. Based on FTIR, XRD, NMR and XPS analysis, the characteristic peaks associated with C = O band of ester were present in CFEF, supporting the successful esterification of cellulose. Overall, this work provides an eco-friendly and effective method to enhance the UV shielding abilities of cellulose, paving the way for its application in high-performance food packaging materials.

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The flammability of most decorative paper poses a potential fire hazard to buildings. In this study, softwood fibers were modified with phytic acid and urea to obtain phytic acid esterified cellulose (PAEC) with good flame-retardant properties. Due to the introduction of phosphorus and nitrogen elements in PAEC, the heat release rate (HRR) and total heat release (THR) decreased from 170.9 W/g and 7.6 kJ/g to 104.3 W/g and 4.9 kJ/g, respectively, when compared with raw fibers. Subsequently, PAEC was composited with talc powder, carboxylated nanofibers, and calcium ions to prepare flame retardant paper. The results indicated that the HRR of the 170.9 W/g of the paper was decreased to 47.0 W/g. The network structure formed by the cross-linking between carboxyl groups in nanofibers and Ca^2⁺ enhanced the paper’s mechanical properties. The strength reached 12.18 MPa, which was 1.4 times as high as that of raw paper. Therefore, the prepared flame-retardant paper is expected to provide a candidate for the preparation of decorative paper.

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In this paper, the flame retardant agent ammonium alcohol polyvinyl phosphate (AAPP) with abundance of nitrogen and phosphorous elements is synthesized. Through a simple impregnation and squeezing method, followed by high temperature baking, AAPP polymer chains are covalently grafted to lyocell, which makes the as-obtained AAPP/lyocell fibers exhibit highly efficient flame retardancy, as well as durability to water and alkali washing. 15%-AAPP/lyocell fibers achieve a limiting oxygen index (LOI) value of 39%. After 20 laundering cycles in water and 2% Na₂CO₃ solution, the LOI could still remain at 32% and 29%, meeting the non-combustible grade requirements. Comparing with raw lyocell fibers, the peak heat release rate and total heat release for 15%-AAPP/lyocell fibers decrease to 10.34% and 47.12%, respectively. The flame-retardant mechanism of AAPP/lyocell is ascribed to nitrogen-phosphorus synergistic effect via dual condensed-phase and gas-phase pathways to suppress combustion. The flame retardant AAPP/lyocell fibers hold great promising in the field of protective clothing for military and firefighting occupations.

The substitution of acetyl groups significantly affects the birefringence properties of cellulose acetate (CA) and is a crucial factor in the design and fabrication of high-performance CA optical films. In this paper, the contribution of CA monomers, their conformations and acetyl substitutions at different sites to the intrinsic birefringence (Δn⁰) was studied by molecular modeling and density functional theory (DFT) calculations. Combined with ¹³C nuclear magnetic resonance (NMR) analysis, the relationship between the monomer composition and birefringence (Δn) of commercial CA was evaluated. The results show that in CA monomers containing C6 acetyl groups (6OAc), the conformational type and proportion of 6OAc will lead to changes in both the sign and magnitude of Δn⁰. Additionally, the contribution of acetyl groups to Δn⁰ at different sites is in the following order: 6OAc > 3OAc > 2OAc, and 6OAc plays a greater role in regulating the Δn⁰ of CA. The measured Δn value of commercial CA is consistent with the theoretical value in terms of the change trend and relative size. This study illustrates the feasibility of calculating and evaluating CA birefringence and its wavelength dispersion by analyzing the substitution situation and combining the theoretical Δn⁰ contribution of the substituent.

Wound healing is a complex physiological process involving a series of intricate cellular events. Despite significant advances in our understanding of these mechanisms and the development of various wound management products, achieving optimal wound healing remains a major challenge in healthcare. Wounds and burn injuries cause not only severe physical trauma but also considerable social and economic burdens for patients. Conventional dressings, such as gauze and bandages, are limited by their vulnerability to infections and other complications. In contrast, recent innovations in cellulose-based wound dressings particularly those incorporating cellulose nanomaterials, have demonstrated great potential in addressing these limitations. Nanocellulose is commonly available in different forms, such as cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs), which can be functionalized with metal oxide nanoparticles like zinc oxide (ZnO) and magnesium oxide (MgO). This comprehensive review highlights recent advancements in the development of cellulose nanomaterial-based dressings, with an emphasis on metal oxide nanohybrid integration. It also discusses the crucial role of biocompatible polymers in enhancing the mechanical strength and adhesive properties of these dressings. Furthermore, the review outlines potential applications and future directions of bacterial cellulose-based wound dressing biomaterials, underscoring their promise to transform wound care paradigms.

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This study presents a robust approach for enhancing the thermal insulation, mechanical durability, and wash stability of organic cotton fabrics (OCFs) through a polydopamine-assisted silver nanoparticle (AgNP) deposition and subsequent thermoplastic polyurethane/silica aerogel/dimethylformamide (TPU/SAP/DMF) composite coating. A systematic investigation of silver-plating reaction time revealed its critical influence on surface morphology, roughness, and coating adhesion. Optimal AgNP growth occurred at 20 min, yielding a 94.9% increase in peel strength and a 91.7% rise in surface roughness. Infrared reflectance was significantly enhanced in the 8–14 μm range, with a peak reflectance of 16.0%, demonstrating the silver layer’s ability to reflect radiative body heat. The coated Ag/OCF composite achieved a skin temperature increase of 2.78 °C and a clo value (a standard measure of clothing insulation, where higher values indicate greater resistance to heat loss) of 0.20, a 122% improvement over untreated OCFs. Additionally, mechanical performance and durability were preserved after multiple washes, highlighting the stability of AgNP anchoring. These findings establish an effective multifunctional textile platform for smart thermal regulation, suitable for advanced clothing systems and adaptive insulation materials.