Cellulose最新文献

Bamboo fibres, which are widely regarded as a contemporary environmentally sustainable resource, have been utilised in various industries including construction materials and packaging sectors. Malaysia possesses a diverse array of bamboo species, rendering it a significant resource for exploration. Five out of the 69 bamboo species discovered in Malaysia were selected for their suitability and availability in the pulp and paper industry, considering properties such as high cellulose content and long fibers. The objective of this study is to conduct a comprehensive analysis of the morphological, physiochemical, thermal, and chemical properties of five specific bamboo species that are often found in Malaysia: Gigantochloa scortechinii (GS), Gigantochloa wrayi (GW), Gigantochloa levis (GL), Schizostachyum grande (SG) and Dendrocalamus asper (DA). Selected from a pool of 69 species based on their availability, these various types of bamboo were subjected to analysis using advanced scientific techniques such as Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), and X-ray Diffraction (XRD). Furthermore, a chemical composition study was performed to clarify the presence of cellulose, hemicellulose, lignin, and ash in all five species. By employing various analytical methodologies, this study investigates and records the properties offered by the bamboo species, providing a significant contribution to the comprehension and knowledge of their potential applications across diverse disciplines. This holds relevance as all five bamboo species are readily available but remain underutilized for further applications in various fields especially in packaging industries.

The food and beverage industry worldwide is trying to switch to using environment-friendly and bio-degradable materials in food packaging to avoid environmental concerns of using petroleum-derived plastic (synthetic polymers) materials. In this study, chitosan (CH) hydrogel films were fabricated by using its derivative chitooligosaccharides (COS) as an additive, polyvinyl alcohol as a plasticiser, and bioactive gallic acid as a cross-linker. The physical, mechanical, structural, barrier (e.g., moisture, water vapour permeability (WVP), and UV-barrier property), thermal properties, and biodegradation patterns of fabricated films were investigated. The use of bio–composite in CH films exhibited a synergistic effect. A film with a homogenous/smooth surface and excellent mechanical and thermal properties was obtained. Additionally, incorporating COS and gallic acid reduced the moisture content, WVP, and transparency. Moreover, the films exhibited good colour, strong UV-barrier properties, and good biodegradable capacity in soil. The results suggest that eco-friendly CH hydrogel films have promising potential to be used in food packaging.

Here, a facile method to extract the carboxylated cellulose nanocrystals (CNCs) with high yield from microcrystalline cellulose (MCC) at room temperature (RT) is put forward that uses a solvent system of zinc chloride (ZnCl₂) and citric acid (CA) aqueous solution. The rod-like carboxylated CNCs were achieved with a maximum yield of 72.3% and a maximum carboxyl group content of 0.75 mmol/g. Meanwhile, the crystal transformation from cellulose I to II was detected with variation of solvent composition. In addition, to the best of our knowledge, this is the first time that the iridescent phenomenon was observed in extremely thin films which were prepared from carboxylated CNC suspension with a concentration of only 0.08–0.15 wt% via evaporation-induced self-assembly. The possible formation mechanism is considered to be related to the synergistic effects of film confinement and drying stresses. Furthermore, the interaction between Petri dish substrate and the film played a role. As the first example of isolation of carboxylated CNCs with high yield at RT using ZnCl₂/CA aqueous solution, this work provides a facile and practical strategy for the preparation of functional cellulose nanomaterials.

Microfibrillated cellulose (MFC) and hydroxypropyl methylcellulose (HPMC) were employed as gelling agents in hydroalcoholic solutions. However, a limited number of studies have explored the interactions between MFC and cellulose derivatives in organic solvents. Most of these studies have primarily focused on either the interactions between MFC and polymers in aqueous solutions. To investigate their collaborative effect, phase diagrams were constructed by varying the concentration of the constituent elements, confirming phase separation, and identifying liquid-like and gel-like properties through oscillatory rheological measurements. Oscillatory amplitude, frequency, oscillatory swing temperature and viscosity were performed. Additionally, aerogels were fabricated with and without ethanol for microscopic analysis. It was demonstrated that ethanol significantly influences the rheological characteristics of MFC and MFC + HPMC dispersions, resulting in an increase in the elastic modulus (G'), decreased thixotropic behavior, and increased stability. Tests were also conducted with urea, a strongly chaotropic agent, providing evidence of the types of interactions governing the systems, and demonstrating that intermolecular hydrogen bond interactions play a predominant role.

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Natural polymer-based hydrogels have importance in tissue engineering, drug delivery systems, and wound dressings due to their non-toxicity, renewability, biocompatibility, and biodegradability. Also, hydrogels can be modified to increase their antibacterial activity and mechanical properties. In this study, a novel nanobiocomposite was fabricated using raffinose (Raff)-carboxymethyl cellulose (CMC) hydrogel, silk fibroin (SF), and AgBTC metal organic framework (MOF). The nanobiocomposite was characterized using Fourier transform infrared (FT-IR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) analyses. After 48 h of incubation, the (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) (MTT) assay of Raff-CMC hydrogel/SF/AgBTC nanobiocomposite on HEK293T cells (human embryonic healthy kidney cell lines) and MCF-7 cells (human breast cancer cell lines) showed that the percentage of cell viability of the two cell lines was 90.46% and 29.18%, respectively. The measured hemolytic activity of the nanobiocomposite on human red blood cells was 2.39%, indicating its safety for use in the human circulatory system, as it did not cause significant hemolysis in erythrocytes compared to the negative control. The potential of the Raff-CMC hydrogel/SF/AgBTC nanobiocomposite to inhibit bacterial growth was investigated, and results showed that E. coli and S. aureus growth was restricted by 60.38% and 57.09%, respectively. As a result, considering the biocompatibility of nanobiocomposite with healthy cells, its antibacterial and anticancer activity, as well as its hemocompatibility, it can be considered a potential candidate for biomedical applications such as wound healing, tissue engineering, and cancer therapy.

Industrialization and human activities have exacerbated water pollution, demanding effective pollutant removal methods. Bio-based hydrogels, with their high porosity and extensive surface area, hold promise for this purpose. Cellulose is a suitable biopolymer for gel fabrication; however, the adsorption capacity of unmodified raw cellulose fibers often falls short of performance expectations due to the lack of strong binding sites. Therefore, this study investigates how different cellulose fiber types, chemical treatments, and solvent systems influence hydrogel properties for adsorption applications. Hydrogels were prepared from phosphorylated and unphosphorylated unbleached kraft pulps (UKP) derived from eucalyptus and pine using NMMO and IL solvent systems. Phosphorylation increased the surface charge of UKP from ~ 0.05 to ~ 2.3 mmol/g. However, the surface charge of phosphorylated samples decreased to 0.5–0.72 mmol/g after coagulation into hydrogels. Hydrogels prepared from phosphorylated UKP exhibited superior properties compared to the unphosphorylated counterparts, including increased specific surface area (12–64 m²/g to 53–95 m²/g), swelling capacity (1930–2800% to 3400–4800%), and higher MB adsorption capacity (13–30 mg/g to 156–291 mg/g). When comparing solvent systems, the NMMO-based hydrogel showed enhanced surface area and pore characteristics, while the IL-based hydrogel exhibited increased MB adsorption capacity (291 mg/g vs. 233 mg/g). Although pine-derived hydrogels had lower MB adsorption than eucalyptus-derived ones (156 mg/g vs. 291 mg/g), both showed comparable adsorption performance for Cu²⁺ ions (~ 40 mg/g). Overall, the IL-derived hydrogel from phosphorylated eucalyptus UKP proved most effective for removing MB and Cu²⁺ from aqueous solutions. These findings contribute to advancing cellulose-based hydrogels for efficient adsorption in wastewater treatment.

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A group of new hydrogel materials combining high physical properties and pronounced antibacterial activity has been developed. These are composite hydrogels “cellulose-polyacrylamide” based on cellulose matrices of two types: bacterial or regenerated plant cellulose. To form biologically active materials, a method of introducing cerium oxide nanoparticles with sizes less than 5 nm was elaborated. The developed technology allows to obtain hydrogels with the content of cerium oxide (in swollen material) up to 0.4–0.5 wt%. Variations of the ratio of gel components concentrations, type of matrix cellulose and synthesis conditions allow to change the complex of mechanical properties of the material within a wide range, in particular, to obtain both soft, low-modular nanocomposites and hydrogels with record high rigidity. Significant differences in mechanical properties of hydrogels based on different types of cellulose fully correlate with the difference in morphological characteristics of these two groups of materials, revealed by SEM. No palpable effect of nanoparticles on the morphological characteristics of the material was revealed. Both cerium oxide nanoparticles and hydrogels containing cerium oxide showed antibacterial activity against S. aureus ATCC 29213, S. aureus ATCC 43300, P. aeruginosa ATCC 27853, K. pneumoniae ATCC 33495. Different intensity of growth depression of the bacterial cells was determined depending on the samples composition and of the bacteria species.

To successfully convert lignocellulosic biomass into value-added products, it is necessary to overcome its structures’ resistance to enzymatic digestion. Pretreatment of lignocellulosic biomass is an inevitable process loosening the carbohydrate-lignin network, thus improving the digestibility/enzymatic saccharification into second-generation sugars. Several pretreatment methods exist; however, steam explosion with or without catalyst, dilute acid hydrolysis, alkaline pretreatment, hydrothermal, and organosolv pretreatment have been studied in detail. Although several pretreatment techniques have been established, the feasibility of these techniques on a large scale remains a major bottleneck in the biorefinery. In this sense, emerging technologies such as supercritical fluids, ionic liquids, hydrodynamic cavitation, and nanobiotechnology have shown encouraging results in terms of process feasibility. This paper discusses the key pretreatment techniques, their advantages, and disadvantages. Additionally, the chemical and physical changes that occurred due to different pretreatments on the biomass at a molecular level are discussed and compared using Microsoft Power BI. Finally, the perspective of emerging technologies is explored, and future trends in biomass pretreatment are provided.

This study systematically investigates the flow birefringence of cellulose nanocrystal (CNC) suspensions. The aim is to clarify the importance of the stress component along the camera’s optical axis in the stress-optic law (SOL), which describes the relationship between birefringence, the retardation of transmitted polarized light, and the stress field. More than 100 datasets pertaining to the retardation of CNC suspensions (concentrations of 0.1, 0.3, 0.5, and 1.0 wt%) in a laminar flow field within a rectangular channel (aspect ratios of 0.1, 1, and 3) are systematically obtained. The measured retardation data are compared with the predictions given by the conventional SOL excluding the stress component along the camera’s optical axis and by the SOL including these components as second-order terms (2nd-order SOL). The results show that the 2nd-order SOL gives a significantly better agreement with the measurements. Based on the 2nd-order SOL, the retardation at the center of the channel, where the effect of the stress component along the camera’s optical axis is most pronounced, is predicted to be proportional to the square of the flow rate, which agrees with the experimental data. The results confirm the importance of considering the stress component along the camera’s optical axis in the flow birefringence of CNC suspensions at high flow rates, even for quasi-two-dimensional channel flow.

Petroleum-based general-purpose polymers, like polyethylene and polypropylene, have become the most economical and practical solution for packaging applications due to their characteristics, such as low cost, excellent optical, mechanical, and barrier properties. However, the significant environmental issues associated with the extensive use of these synthetic polymers have prompted searches for new sustainable alternatives. In pursuit of a carbon–neutral economy, the aim of this work is to develop a nanocomposite film combining high barrier property and transparency, suitable for packaging purpose, utilizing commercial cellulose derivatives (carboxymethyl cellulose, CMC) and 2D non-toxic layered double hydroxide nanosheets (LDH-NSs). Employing a simple, eco-friendly method, the nanocomposite films (CMC/LDH-NS) are fabricated by mixing and casting a mixed suspension from a CMC solution and an LDH-NS suspension, facilitated by a non-toxic exfoliation method in an aqueous amino acid solution. The effects of different ratios of LDH-NS on the barrier properties and transparency of the nanocomposite films are studied, along with the related mechanism through comprehensive analysis of micromorphology, X-ray diffraction, and Fourier-transform infrared spectroscopy. The CMC/LDH-NS films present a remarkable 252-fold increase of oxygen barrier and a 51% improvement in water vapor barrier performance compared to the pure CMC film. Moreover, the nanocomposite films maintain high light transmittance, with values exceeding 80% at 600 nm, even at a 50% LDH-NS:CMC ratio. These outstanding attributes underscore the potential of CMC/LDH-NS nanocomposite films for broad application in food and pharmaceutical packaging, as well as in electronic encapsulation, marking a significant step forward in the development of sustainable packaging solutions.