Cellulose最新文献

Dry thermoformed paper-based materials have been used in the food packaging industry due to their biodegradability and recyclability. However, the poor barrier properties limit applications to certain products. In the past, some paper-based tableware relied on per-and polyfluoroalkyl substances (PFAS) to obtain the oil-resistant properties required by consumers. However, due to health and environmental concerns, there is a quest for alternative biodegradable materials for single-use food packaging. Cellulose nanofibrils (CNFs) applied to paperboard yield excellent oil barrier properties even after folding. However, it is unclear how CNF layers perform after a dry thermoforming event. In this study, different qualities of CNF films are formed on paperboard through vacuum dewatering. The properties of the paperboard with the CNF layer and other coatings were determined. Plates are then formed with a plate former using the fabricated paperboard. The corn oil Cobb value of the paperboard decreased from 220 to 5 g/m² after CNF coating, indicating an enhanced oil barrier property. After folding, it retained its oil barrier property with only a slight increase in corn oil Cobb value to 14 g/m² and passed a Kit test of 12. This value is comparable to those of many PFAS coated paperboards reported in literature (Kit value usually greater than 9). As CNFs are hydrophilic, different water-based dispersion coatings were explored to enhance the water barrier properties. The added coatings did not deteriorate the oil barrier properties. Biowax (BW), alkyl ketene dimer (AKD), and styrene acrylic latex (SAL) showed promising results with a reduction in water Cobb value from 350 g/m² to 5, 20, and 6 g/m² for coat weights of 15, 9, and 8 g/m², respectively. Barrier properties were retained after thermoforming into plates. The fabricated plates exhibited better oil barrier properties and comparable water barrier properties to those of randomly selected commercial paper plates. This should be of value to the food packaging industry in producing PFAS-free tableware.

Graphical Abstract

This work describes the interfacial bond characteristics of a novel natural fiber laminate system. The natural fiber laminates are fabricated by combining a bi-directional natural fiber mat (flax or hemp) and discrete natural fiber-reinforced ultra-high toughness cementitious composites (UHTCC). To utilize the proposed bio-fiber laminates for retrofitting applications, it is essential to understand the bond between the existing concrete and proposed UHTCC matrix and the natural fiber mat and UHTCC matrix. Hence, the present work experimentally investigates the bond characteristics through (a) a slant shear test, (b) a pull-out test, and (c) a four-point bending test. Moreover, a detailed techno-economic sustainability analysis was carried out using the cradle-to-gate principle to understand the economic aspect and environment-friendly nature of the proposed laminate system. Experimental results reveal that the hybrid combination of hemp mat and flax UHTCC matrix showed a high bond stress of 8.64 N/mm². Moreover, the micro-structural analysis revealed a strong interfacial bonding between the fiber and UHTCC matrix. From the sustainability analysis, it can be inferred that the cost required for fabricating a bio-composite panel is less expensive, ranges between 0.5–0.65 dollar ($), require less energy of 0.0053 gigajoule (GJ), and has a reduced carbon footprint of 3.324 to 4.568 kg-carbon-di-oxide- equivalent/cubic meter (kg-CO₂-eq/m³).

In this research, hybrids (NH-CMC-nSiO₂) were synthesized using a carbodiimide-mediated amidation reaction from carboxymethylcellulose (CMC) obtained from cellulose extracted from cotton linters and amino-functionalized silica nanoparticles (nSiO₂-APTES). One of the nanoparticles was obtained commercially (nSiO₂-2% APTES), while the others required the corresponding amino-functionalization reaction with the respective aminosilane (APTES). The precursors and products were characterized by spectroscopic (FTIR-ATR, DLS, Pζ, XRD, XPS, SEM, EDS) and thermogravimetric (TGA and DSC) techniques. Additionally, the viscosifying and gelation capacity of NH-CMC-nSiO₂ solutions and its precursor biopolymer solutions were evaluated under different temperature and salinity conditions. The results reveal that the hybrid materials show similar thermal properties, but differ in morphology, chemical structure, and crystallinity properties compared to CMC’s. Subsequently, a viscosity study was performed on the new obtained hybrid materials; the viscosities of the hybrids increased significantly compared to carboxymethylcellulose, with a viscosity difference of 9 cP for NH-CMC A380-APTES. Finally, the gelation kinetics and thermal stability of the gels at different concentrations of the new nanomaterials and cross-linker were evaluated, validating that these materials are suitable for being incorporated into chemical conformance treatments.

Microfibrillated cellulose or cellulose microfibrils (CMF) are promising materials with versatile applications. However, the utilization of CMF is limited due to the high cost of production. In the present study, CMF were prepared from spruce bark subjected to different intensities of chemical pretreatment and used for nanocomposite preparation. Spruce bark was delignified using various methods, including subcritical water extraction, neutral sulfite semi-chemical pulping, and peracetic acid treatment. The pretreated bark was mechanically fibrillated and the resulting CMF suspensions were processed into cellulose nanopapers. For composite preparation, the latter were impregnated with phenolic resin and hot-pressed to form a composite laminate. Nanopapers and composites were characterized in tensile and flexural tests, respectively. Results showed that the chemical composition, morphology, and physical properties of cellulose nanopapers were highly dependent on the pretreatment method. The thermal stability of nanopapers was found to increase with increasing lignin content. All treated samples showed nanoscale cellulose fibrils with diameters ranging from 8–16 nm with average tensile strength and Young’s modulus of 29–114 MPa and 5–12 GPa, respectively. Furthermore, the prepared composites demonstrated promising flexural properties with values of 109–195 MPa and 8–13 GPa for flexural strength and modulus, respectively. Despite the low purity of CMF used herein, the flexural properties of the resulting composites exceeded that of similar nanocomposites reported in previous studies. The findings of the present study thus indicate that a composite with favorable mechanical properties can be prepared from spruce bark, a resource typically not put to material use.

The sustainable processing of natural fibres, such as ramie (Boehmeria nivea) bast fibres and pineapple (Ananas comosus) leaf (PAL) fibres is limited by the presence of non-cellulosic components like pectin, hemicellulose and lignin. In this study, an eco-friendly enzymatic degumming strategy was developed by using three crude recombinant carbohydrate-active enzymes viz.: xylobiohydrolase (AcGH30A), pectate lyase (CtPL1B) and mannanase (RfGH5_7). The optimised concentration for all three crude enzymes was determined to be 15 mg·mL⁻¹ and the enzyme reactions were performed under optimised conditions of 50 °C, pH 7.5 and 100 rpm for 60 min. The maximum degumming efficiency among multi-enzyme treatments, measured by fibre weight loss, was 11% for ramie (AcGH30A + CtPL1B) and 18% for PAL fibres (CtPL1B + RfGH5_7), closely matching with that of chemical, NaOH treatment (15.0 ± 0.6% for ramie, 21.0 ± 0.4% for PAL). FESEM analysis revealed smoother fibre surfaces post-enzymatic treatment, while ATR-FTIR spectra confirmed substantial removal of pectin and hemicellulose. Thermogravimetric analysis showed improved thermal stability of the enzyme-treated fibres, with degradation temperatures elevated to 356.3 °C from 338.8 °C for ramie and to 377.1 °C from 361.0 °C for PAL untreated fibres, indicating higher purity and crystallinity. Tensile strength improved in enzyme-treated ramie and PAL fibres to 418.3 and 323.2 MPa, respectively, from 388 and 270 MPa in untreated fibres. The optimised enzymatic treatment provided a viable and sustainable alternative to conventional chemical degumming, enabling the valorisation of underutilised biomass like pineapple leaves, thereby supporting eco-friendly practices in the fibre processing and textile industries.

Graphical abstract

This study investigates the dissolution of flax yarns in two imidazolium based ionic liquids ILs (1-butyl-3-methylimidazolium acetate) ([C4mim]⁺[OAc]⁻), and (1-ethyl-3-methylimidazolium octanoate) ([C2mim]⁺ [Oct]⁻). These results are combined with our previous published work on (1-ethyl-3-methylimidazolium acetate) ([C2mim]⁺[OAc]⁻) (Albarakati et al.2023) using the same flax yarns, to establish an understanding of the effect of the anion and cation on dissolution behaviour. The dissolution process involved submerging the flax yarns in the ILs for a range of temperatures and times, followed by coagulation in water. The dissolved coagulated material produced an outer ring that surrounded the centre undissolved yarn. Optical microscopy was used to follow the growth of this region, which was found to follow an Arrhenius behaviour. The dissolution activation energies of the ILs [C4mim][OAc] and [C2mim] [Oct] were found to be 67 ± 1 kJ/mol and 79 ± 1 kJ/mol, respectively. In addition, the growth of the outer coagulated ring’s thickness was measured with time and temperature, enabling the IL’s diffusion to be determined. Nuclear Magnetic Resonance, viscosity and density measurements were combined through a Stokes–Einstein analysis to further understand the dissolution mechanisms. Comparing the resultant data for all three ILs shows that the dissolution rate goes from fastest to slowest in the order [C2mim][OAc] > [C4mim][OAc] > [C2mim][Oct]. Our key observation is that the dissolution of the flax yarns (in all three ILs) is controlled by the diffusion of each IL through a region of swollen cellulose/IL solution around each yarn as it dissolves.

Cellulose nanocrystals (CNCs) self-assemble into cholesteric phase liquid crystals (CPLCs) at a critical concentration in aqueous suspension. The resulting helical structure is retained in the solid-state film, generating left-handed circularly polarized structural color. Optical materials based on CNC CPLCs have attracted extensive interest; however, their assembly is highly sensitive to environmental and interfacial conditions, complicating structural color control. This study investigates the effects of substrate surface properties—surface energy, water absorption, and contact angle—on the self-assembly of CNC photonic thin films. Responsive CNC-based cholesteric films were fabricated by incorporating glucose (Glc) and carbon black (CB) into CNC suspensions and co-assembling the mixture on printing paper via evaporation-induced self-assembly (EISA). The resulting films exhibit a left-handed helical architecture with birefringence and show high humidity response across the ultraviolet (UV) to near-infrared (NIR) range. The CNC/Glc/CB composite films also demonstrate excellent stability and reversibility, offering a promising strategy for applications such as humidity sensing and information encryption.

Graphical Abstract

Unidirectional conductive wet fiber materials are employed in membrane materials because of their directional transport capability. In this study, a Janus membrane with directional transport function was prepared by electrospinning method using cellulose acetate butyrate (CAB) as the main raw material. In order to obtain a hydrophilic nanofiber membrane, the CAB nanofiber membrane was modified to be hydrophilic, and the modified nanofiber membrane was subjected to analysis of membrane density, porosity, contact angle, and FTIR. Finally, the CAB nanofiber membrane was sprayed onto the modified nanofiber membrane using an electrospinning device to obtain the Janus membrane, and its pore structure and single transport capacity were analyzed. The results show that the Janus membrane exhibits a unidirectional moisture conductivity index R of 1037.53, which reaches Level V, and the asymmetric structure and pore size gradient provide the driving force for the unidirectional moisture conductivity.

The aim of this research was to investigate the important features of teff straw fibers and its utilization in the pulp and paper industry through soda-anthraquinone pulping process. Morphological characterization indicated the average length of teff straw and the derived indices were comparable to the most non-wood plants and Eucalyptus. The chemical composition analysis of teff straw showed a cellulose content of 39.4%, hemicellulose of 29.6%, lignin of 14%, extractive of 7.2%, and ash content of 6.78. Response surface methodology with central Composite design was used to compare and optimize the effects of cooking temperature 130℃ to 150℃, cooking time 60 to 120 min, active alkali concentration 10 to 20% w/v and 0.20% w/w of anthraquinone based on oven dried teff straw. The responses evaluated were pulp yield and kappa number. The predicted optimized pulping results yielded 64.00% pulp (based on oven-dried teff straw) with a kappa number of 8.28. FTIR analysis confirmed the elimination of the non-cellulosic fiber compositions. The paper hand sheets of 60 g/m² were prepared from the pulps produced at optimal conditions and tested for its mechanical properties showing breaking length of 4294 m, tensile strength of 11.6 kN/m, tensile index of 42.1 Nm/g, tear index of 5.2 mN.m²/g, burst index of 1.41 kPa.m²/g, and porosity of 19.5 se/100 air. The results indicated the tested morphological, chemical and strength properties were acceptable and made teff straw an alternative material for pulp and paper application.

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.