Cellulose最新文献

Cellulose offers potential applications across various fields, enhancing the mechanical strength, insulation properties, and high-temperature resistance of fiber-reinforced composites through its high aspect ratio characteristics. Despite this, challenges remain due to difficulties in dispersion within the polymer matrix and chemical compatibility. In this study, we fabricated three-component supramolecular nanocomposite films, exploring their morphology, mechanical, and thermal properties. The films were reinforced with heterocyclic aramid nanofibers and cellulose nanocrystals in a poly(vinyl alcohol) (PVA) matrix. Additionally, we describe the production of heterocyclic aramid nanofibers using a microreactor. The findings reveal that the nanocomposites exhibit enhanced strength and toughness due to robust hydrogen bonding between the matrix and fillers. Optimal results were obtained with a composition of 3 wt% heterocyclic aramid nanofiber and 5 wt% cellulose nanocrystals in PVA, displaying a 2–5 fold increase in tensile strength, Young’s modulus, and elongation at break compared to pure PVA. Additionally, these films showed improved electronic breakdown strength and thermal stability. These findings highlight the potential of integrating heterocyclic aramid nanofibers and cellulose nanocrystals as innovative polymer reinforcement materials.

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Air filtration materials have become a focal point due to the increasing concern over global air pollution. However, it remains challenging to achieve an optimal balance between reliable filtration performance and superior mechanical strength, particularly across diverse applications. Herein, a novel composite air filter paper was designed by integrating hardwood pulp and glass fiber through a straightforward paper-making process. Our findings indicate that the incorporation of hardwood pulp enhanced the tensile strength of the composite paper, achieving a tensile index of 15.22 N m/g, while simultaneously maintaining commendable filtration performance, as evidenced by a quality factor of 2.15 Pa^–1. Furthermore, the in-situ growth of silver nanoparticles (AgNPs) endowed the composite paper with stable antibacterial properties, as demonstrated by inhibition zones measuring 1.52 mm and 2.04 mm against E. coli and S. aureus, respectively. The favorable mechanical, filtration, and antibacterial properties, make this composite paper an ideal candidate for practical applications across various scenarios. Our research establishes a solid foundation for further advancements in antimicrobial filtration, highlighting the potential of cellulose-based materials in air purification as a viable strategy for combating air pollution and protecting human health.

Tubular esophageal grafts have been widely studied for their potential in replacing tissue damaged by esophageal cancer. However, developing readily available grafts for clinical use remains challenging due to high rates of esophageal leakage and limited biocompatibility. Herein, bilayer bacterial cellulose (BC)/poly(vinyl alcohol) (PVA)/glycerol (Gly)-PVA/silk microfiber (SMF) tubes were developed, featuring an inner BC/PVA/Gly layer and an outer PVA/SMF hydrogel sheath. The tubes were fabricated through a combination of rolling and freeze-thawing, creating a strong inner BC/PVA/Gly layer and a bioactive outer PVA/SMF hydrogel layer. The effects of the inner layer’s thickness and SMF content on the morphology, microstructure, thermal stability, mechanical properties, suture retention strength, and burst pressure strength of the bilayer tubes were examined. The inner BC/PVA/Gly tubes exhibited a compact structure, while the outer PVA/SMF sheaths had a porous architecture. The mechanical properties, suture retention strength, and burst pressure strength of the bilayer tubes were much greater than that of the native esophagus. Hemocompatibility and cytocompatibility testing confirmed the excellent blood compatibility and strong biocompatibility of these new bilayer tubes, largely attributed to the SMF content. These characteristics highlight the potential of bilayer BC/PVA/Gly-PVA/SMF tubes as promising candidates for esophageal graft applications.

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Globally, there is a significant concern about controlling the growth of pathogenic microorganisms to prevent infectious diseases. In this context, the study focused on the synthesis of a nanocomposite via the Ugi multicomponent reaction using silanized titanate nanotubes [NtsTi–Si(CH₂)₃NH₂] and bacterial nanocellulose (BNC–COOH) with antimicrobial properties. The NtsTi–Si(CH₂)₃NH₂ exhibited antimicrobial activity, with inhibition halos of 21 mm against S. aureus and 25 mm against E. coli. Additionally, the [BNC–COOH/NtsTi–Si(CH₂)₃NH₂] nanocomposite was tested against Gram-negative and Gram-positive bacteria, showing inhibition halos of 9 mm against E. coli and 15 mm against S. aureus, indicating sensitivity comparable to that of chloramphenicol.

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A phosphorus‑nitrogen synergistic flame retardant polymer (FR-P) was synthesized by condensation reaction of tetrakis(hydroxymethyl)phosphonium chloride-urea (THPC-Urea) with ammonia, resulting in a polymer containing 17.71% phosphorus and 18.43% nitrogen. The FR-P was characterized using thermogravimetry (TG), Fourier-transform infrared spectroscopy (FTIR), inductively coupled plasma (ICP), and X-ray photoelectron spectroscopy (XPS). Flame retardant lyocell fibers (FR-L) were subsequently prepared using dry–wet spinning technology, with FR-P incorporated as a filler. The flame-retardant properties were evaluated using the limiting oxygen index (LOI), thermogravimetric analysis coupled with FTIR (TG-FTIR), and TG. The results indicated that the incorporation of 26 wt % FR-P brought a 31.6% LOI, which remained at 29.3% even after 30 laundering cycles (LCs). The pyrolysis mechanism of cellulose was changed by FR-P which played a crucial role in the condensed phase during combustion by catalyzing the dehydration of cellulose to form a compact char layer structure. Under a nitrogen atmosphere at 700 °C, the char residue of FR-L was 37.42%. The char residue was characterized using raman spectra, and scanning electron microscopy (SEM). The results indicated that the char residue exhibited a higher degree of graphitization. Furthermore, the mechanical properties were tested by fiber strength and elongation tester. The results showed that the draw ratio increased from 4.11 to 6.88, while the tensile strength of FR-L remained at 3 cN/dtex. The crystal structure of the fibers was characterized by X-ray diffraction (XRD), revealing that the crystallinity of the fibers was cellulose II. At a draw ratio of 5.27, the crystallinity was measured at 61.0%.

Numerous studies have investigated the use of cellulose hydrogels produced via the dissolution–regeneration method. However, using different cellulose solvents, a comprehensive comparison of their structures and properties has yet to be reported. In this study, we prepared cellulose hydrogels using six different solvents: LiCl/N,N-dimethylacetamide (DMAc), 1-butyl-3-methylimidazolium chloride, NaOH/urea, ZnCl₂/AlCl₃, LiBr, and Ca(SCN)₂ solutions with the same cellulose concentration and evaluated their structure, transparency, and mechanical properties. Depending on the cellulose solvent used, significant differences in volume shrinkage were observed during regeneration and washing with water. The cellulose hydrogels prepared from LiCl/DMAc and NaOH/urea solutions showed the most significant volume shrinkage during regeneration and washing. Greater volume shrinkage resulted in a higher solid cellulose content in the hydrogel. A positive correlation exists between solid content and both elastic modulus and strength. The cellulose hydrogel prepared from LiCl/DMAc showed excellent mechanical properties: compressive modulus of 332 kPa, tensile modulus of almost 1000 kPa, and ultimate tensile strength of 523 kPa. The cellulose hydrogels prepared from LiBr and Ca(SCN)₂ solutions showed negligible volume shrinkage and lower solid content. However, the elastic modulus and strength of the hydrogels were relatively high despite their solid content due to the three-dimensional network structure composed of nanofibers. Moreover, the transparency was higher for the hydrogels prepared from LiCl/DMAc with amorphous cellulose and a uniform internal structure. These findings could assist in customizing the material properties of cellulose hydrogels.

To address the issue of deterrent migration in current nitrocellulose-based propellant, this study designed a UV-curable deterrent. The deterrent precursor penetrates the propellant to a certain depth, after which UV irradiation induces a curing reaction, producing a UV-curable deterrent propellant. Scanning electron microscopy, energy-dispersive spectroscopy, and confocal laser Raman spectroscopy (Raman) were employed to observe the surface morphology of the UV-cured deterrent propellant and analyze the elemental distribution of its surface and internal structural composition. Additionally, thermogravimetric–differential scanning calorimetry was used to investigate the impact of the UV-curable deterrent on the thermal decomposition performance of the propellant and to evaluate its compatibility with the propellant. Molecular dynamics simulations were further conducted to examine the diffusion behavior of the deterrent within the propellant system before and after curing, explore the diffusion mechanism, and compare the diffusion rates before and after curing. The results indicate that the UV-curable deterrent effectively reduced the concentration of energetic nitro groups (–NO₂) on the propellant surface. When the deterrent concentration was 7%, the nitrogen content on the surface decreased from 13.5 to 12.82%. Confocal laser Raman spectroscopy revealed that the I₁₁₀₃-to-I₁₂₈₅ ratio (I₁₁₀₃/I₁₂₈₅) of the UV-polymer deterrent gradually decreased from 53.09% at 5 μm to 16.48% at 80 μm, establishing a gradient distribution of the deterrent within the propellant. The molecular dynamics simulation results demonstrated that, following UV-induced curing, the deterrent diffusion coefficient decreased from 41.0 × 10⁻¹⁰ and 18.8 × 10⁻¹⁰ to 3.5 × 10⁻¹⁰ m²s⁻¹, indicating that the UV-curable deterrent provides excellent antimigration properties while achieving efficient precursor penetration.

This study presents a method for preparing biobased cellulose diacetate (CDA)/polyester blends. The method involves melt blending CDA with polybutylene adipate (PBS), polybutylene adipate/terephthalate (PBAT), or poly-L-lactic acid (PLLA) without the addition of any small molecule plasticizers, with the inclusion of 0.5 phr phosphite antioxidant Bis-(2,4-di-tert-butyl phenyl) pentaerythritol diphosphite (BPE-DP). The ratio of cellulose acetate to polyester is 8:2, 7:3, 6:4, and 5:5. CDA, PBS, and PLLA are common bio-based plastics, and PBAT can also be produced using bio-based monomers. This study leverages the high glass transition temperature (T(_g)) of CDA to develop CDA/polyester blends with high melt fluidity and good resistance to heat-induced deformation, after addressing the challenges of hot processing without small molecule plasticizers. This material has the potential to be applied in high-heat environments, such as car engine, and can be fully bio-based.

Separating emulsified oil/water mixture is full of challenges. Special permeable wetted surfaces can separate emulsions but usually require modification by fluorine or silicon based chemicals, which can cause second pollution after use. Carbon aerogels are porous hydrophobic materials, which provide a promising approach to selectively adsorb oil from oil water mixture. However, during the course of the fabrication of carbon cryogels, freeze drying is essential, which is time-consuming and energy-intensive process. In this article, we introduced wet papermaking technology manufacturing base paper to replace freeze drying, followed by carbonization in N₂ at 800 ºC, hydrophobic carbon paper with a porosity of 90.22% was obtained when the content of micro glass fiber was 70%. The resulting carbon paper not only separates oil slick but also separates water-in-oil emulsion with an efficiency of 98.5% and flux of 1200 L/m²·h.

Superhydrophobic cotton fabric is regarded as an accessible and efficient technology for oily wastewater cleanup because of high porosity, switch wettability, and low cost. However, the existing superhydrophobic fabrics cannot maintain durable superhydrophobicity during practical application due to poor action force between hydrophobic substance and fabric. Herein, a robust and durable fluorine-free superhydrophobic cotton fabric was successfully fabricated through a facile two-step modification process. Firstly, amino-functionalized SiO₂ nanoparticles were chemically bonded to the cotton fabric surface, creating a rough structure with peaks and valleys. Subsequently, the surface was coated with a layer of hydrophobic polydimethylsiloxane (PDMS) for surface modification, resulting in a superhydrophobic surface effective for the separation of oil–water mixtures. The as-prepared superhydrophobic cotton fabric (PDMS-SiO₂@cot) presented superhydrophobic property with water contact angle reached 156.7°. Meanwhile, the prepared PDMS-SiO₂@cot can effectively separate various oil–water mixtures with high separation efficiency (98.2–99.4%). Furthermore, the superhydrophobic cotton fabric demonstrated remarkable robustness by maintaining its hydrophobic characteristics after being subjected to a series of durability tests, including immersing into various solutions (acidic solution, alkaline solution, and organic solvents), and exposing to ultrasonication and mechanical stress (scraping, adhesive tape peeling, and sandpaper abrasion). In conclusion, the as-prepared superhydrophobic cotton fabric PDMS-SiO₂@cot with excellent mechanical stability, chemical resistance, and self-cleaning properties shows considerable potential for oily water remediation.

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