Figure - available from: Cellulose
This content is subject to copyright. Terms and conditions apply.
Cellulose chains functionalized via: a carboxylate groups (TEMPO), b Carboxymethylated (CM) groups and neutralized by Na⁺ counterion (in orange), c TEMPO-modified amorphous cellulose film at initial dry state and final hydrated state when subjected to 80% RH and temperature of 285 K. Insets at the bottom show a representative cellulose chains; water molecules are depicted in blue. d Array of four TEMPO-modified cellulose nanocrystals arranged in bundle at initial dry state and hydrated state when subjected to 80% RH at 285 K. The cellulose chains and water molecules are shown in grey and blue color respectively
Source publication
Foams made from cellulose nanomaterials are highly porous and possess excellent mechanical and thermal insulation properties. However, the moisture uptake and hygroscopic properties of these materials need to be better understood for their use in biomedical and bioelectronics applications, in humidity sensing and thermal insulation. In this work, w...
Citations
... Consequently, less than 1% of adsorbed water can intercalate between crystalline cellulose sheets, indicating that water molecules are more readily absorbed in the disordered amorphous regions [42]. It elucidates that the treated ramie fibres (IPF@OPT and CMF) adsorbed more moisture than the raw ramie fibre. ...
Deep shade dyeing of ramie fibre is challenging due to its high degree of polymerisation, orientation, and crystallinity. The present work involved pre-treating ramie fibre with a solution containing a mixture of NaOH and alcohol in order to improve its dyeing ability. Based on the first screening results, it has been shown that iso-propanol is the optimal alcohol solvent for modifying ramie fibres with a mixture of NaOH solution, resulting in greater levels of dye exhaustion (E%), dye fixation rate (F%), total dye fixation efficiency (T%), and K/S values. Subsequently, the orthogonal array experimental technique (L16) was utilised to optimise the treatment conditions, and it was determined at a temperature of 25 °C, using a NaOH solution with a concentration of 140 g/L, a liquid ratio of 1:2 for the volume ratio of NaOH solution to iso-propanol solvent, and a treating period of 3 min. The treated samples were subjected to a range of analytical techniques, including XRD, FTIR, TGA, and SEM; these analyses conclusively verified that the samples' properties were altered due to the optimal combination treatment. The combination solution-treated samples had significantly higher barium values compared to the other samples, suggesting an ideal mercerisation treatment. The colourfastness to washing values exhibited satisfactory results for the treated samples. Besides, a handle assessment of raw ramie fabric and treated ramie fabric was conducted to enhance the practical application feasibility.
... The regenerated cellulose (RC) hydrogels had a yield of 97.1 % and a polymerization degree of 71 % of those of original cotton cellulose [19]. Besides, a few attempts have been made to dissolve the low contents of cellulose (2-3 wt%) in 64 wt% H 2 SO 4 solution at low temperatures to produce RC films with tensile strengths of about [60][61][62][63][64][65][66][67][68][69][70]20,21]. ...
... This discrepancy could be attributed to the interplay between moisture sorption and material porosity. Although RC-N4 exhibited a higher CI, its lower density and higher porosity facilitated moisture absorption within the films [60,61]. The comparison of WVP values of RC-N4 and RC-H films is illustrated in Fig. 5B. ...
Forests are a major source of wealth for Canadians, and cellulose makes up the “skeleton” of wood fibers. Concentrated H2SO4 and NaOH/urea aqueous solutions are two efficient solvents that can rapidly dissolve cellulose. Our preliminary experiment obtained regenerated wood cellulose films with different mechanical properties from these two solvents. Therefore, herein, we aim to investigate the effects of aqueous solvents on the structure and properties of wood cellulose films. Regenerated cellulose (RC) films were produced by dissolving wood cellulose in either 64 wt% H2SO4 solution (RC-H4) or NaOH/urea aqueous solution (RC-N4). RC-H4 showed the higher tensile strength (109.78 ± 2.14 MPa), better folding endurance (20–28 times), and higher torsion angle (42°) than RC-N4 (62.90 ± 2.27 MPa, un-foldable, and 12°). The increased cellulose contents in the H2SO4 solutions from 3 to 5 wt% resulted in an improved tensile strength from 102.61 ± 1.99 to 132.93 ± 5.64 MPa and did not affect the foldability. RC-H4 also exhibited better water vapor barrier property (1.52 ± 0.04 × 10−7 g m−1 h−1 Pa−1), superior transparency (~90 % transmittance at 800 nm), but lower thermal stability compared to RC-N4. This work provides special insights into the regenerated wood cellulose from two aqueous solvents and is expected to facilitate the development of high-performance RC films from abundant forestry resources.
... These studies have primarily concentrated on cellulose crystal deformation and were exclusively conducted at 300 K (Fujisawa et al., 2023;Ogawa et al., 2020). Moreover, the wettability process and the effect of water molecule adsorption on modified nanocellulose surfaces have been evaluated through MD simulations (Chen et al., 2020;Garg et al., 2021;Sridhar et al., 2023). In these studies, fibers and Iβ-cellulose crystals were placed in a simulation box filled with water molecules to evaluate the cellulose-water molecular interaction. ...
... The addition of microfibrillated cellulose appreciably decreased stain resistance even at concentrations as low as 0.10 wt%, due to the highly hydrophilic and hygroscopic nature of cellulose. 51 The improved stain resistance did not correlate directly with higher advancing contact angle, as shown Fig. 3(b). Both nanofibers demonstrated a significant ( p < 0.05) increase in advancing contact angle relative to the commercial interior acrylic paint ( Fig. 3(b)), but addition of PS fibers led to a slightly higher contact angle than FF fibers. ...
Nanofibers synthesized by PISA-RAFT and added into pigmented commercial paint improve stain resistance, extensibility and toughness.
... In this scenario, germination is due largely to the water content present in the CNCs and, to a lesser extent, their capability to adsorb moisture. In environments with high relative humidity and low concentrations of CNCs, the model is flipped: Because of hydrogen bonding, water adsorption is the primary factor that makes germination occur (Garg et al., 2021). The abundance of hydroxyl functional groups in CNCs makes them highly susceptible to water molecule attraction through hydrogen bonding, given that water also possesses hydroxyl groups. ...
Cellulose nanocrystals (CNCs) were extracted from waste corrugated cardboard (WCC), waste paper towel (WPT), and waste paper towel cardboard roll (WPTR) using modified chemical methods. Instead of being discarded in landfills, these household waste materials were recognized as cost-effective and readily available sources for producing CNCs, which can serve as efficient water adsorbents in agricultural applications. Despite the inherent impurities and contaminants in household waste, the pretreatment and acid hydrolysis processes were found to be effective in removing a significant portion of these undesirable substances, as confirmed by FTIR spectra analysis. The extracted CNCs displayed a needle/whisker-shaped morphology with diameters ranging from 4 to 15 nm. Crystallinity levels of the CNCs extracted from WCC, WPT, and WPTR were determined to be 81.11 %, 85.29 %, and 80.68 %, respectively. The CNCs were then tested for their role as promoters of seed germination in plant starter plugs under different relative humidity conditions. Results indicated that under high relative humidity (above 70 %), seeds exhibited rapid germination (within 3–4 days) when the plugs were coated with CNCs at a minimum concentration of 5 %. However, under moderate relative humidity (50 %), germination occurred within 5–6 days at CNC concentrations of 10–15 %.
... High hemicellulose content and low crystallinity were found to correlate with high water uptake ability (Table 3). This is expected since hemicellulose is shown to increase water retention (Schild and Liftinger 2014) and amorphous cellulose is known to have higher moisture uptake compared to crystalline cellulose (Garg et al. 2021). ...
Hemicellulose-rich pulp raw materials are avoided in the production of man-made cellulosic textile fibres due to hemicellulose reactivity with the currently used industrial solvent systems. Incorporation of hemicelluloses in regenerated fibres could, however, increase the share of used wood biomass and thus improve the environmental footprint of regenerated fibre products. Superbase ionic liquids have shown potential in dissolving and regenerating all the major wood polymers i.e. cellulose, hemicellulose and lignin into regenerated products. In this work, regenerated fibres were spun from hemicellulose-rich softwood and eucalyptus paper-grade pulps and eucalyptus dissolving pulp using a superbase ionic liquid [mTBNH][OAc]. Before dissolution and spinning, intrinsic viscosities of the paper-grade pulps were adjusted either enzymatically or by using a mild acid-treatment to improve dope rheology for dry-jet wet spinning. In fibre spinning, hemicellulose was found to regenerate in high yield and the obtained regenerated fibres had high dry tenacities (5.3 to 15 cN/dtex). The best mechanical properties were measured from fibres with high hemicellulose content (17.3% (w/w)). Pulp pretreatment was found to be critical for achieving good mechanical properties. Acid-pretreatment, which modified both cellulose and hemicellulose, yielded regenerated fibres with better mechanical properties compared to an enzyme-pretreatment which did not alter the hemicellulose structure. Removal of hemicellulose substituents and hydrolysis of hemicellulose backbone in acid-pretreatment may be the key to improved mechanical properties in hemicellulose-containing regenerated fibres. Enzymatic peeling and imaging with a xylan-specific monoclonal antibody (CCRC-M138) suggest that hemicelluloses were enriched to the outermost layers of the regenerated fibres.
... CNF production can involve a wide array of different operations (Fig. 10), resulting in a myriad of different CNF variants [229]. The general processing of cellulose to CNF involves sourcing the raw material (typically softwood/softwood pulp or hardwood/hardwood pulp), purification (typically via Kraft process or, sulfite process, and bleaching), mechanical pretreatment, biological/chemical pre-treatment (typically enzymatic, TEMPO-mediated carboxylation or sulfonation), principle mechanical treatment (typically refining, homogenization or grinding) and post-treatment [229,231,235]. ...
... As humidity increased, thermal conductivity initially decreased due to nanofibril swelling (increases inter-fibrillar distance, decreasing thermal boundary conductance) then increased sharply (at~70 % RH) as air displacement by water became the dominant effect As CNFs became thinner, moisture-dependent phonon scattering was enhanced, reducing thermal conductivity [235] Studied moisture uptake via simulations (hybrid Molecular Dynamic (MD) and Grand Canonical Monte Carlo (GCMC)) and experimental measurements at varying temperatures and relative humidity levels in cellulose films and foams composed of 1) TEMPOoxidized CNFs (TCNFs) and nanocrystals (TCNCs) 2) carboxymethylated CNFs (CMCNFs) ...
... A significant area of uncertainty related to the development of CNF foams is the effects of moisture on foam properties. As cellulose is naturally hygroscopic (due to the presence of hydroxyl surface groups), the thermal and mechanical properties of CNF foams can vary significantly during exposure to humid environments [235]. Thus, several studies have focused on quantifying and reducing the effects of moisture on CNF foam properties [235,255,259]. ...
A surge of research into renewable foams has yielded an array of high‐performance polymeric materials, many of which exhibit promising properties for next generation thermal insulating materials. Biobased materials are of particular interest, due to growing concerns towards enhancing the circular economy while reducing fossil fuel dependency in the construction industry. This review outlines recent developments in biobased foams based on biobased polyurethanes (BPU), biobased phenol formaldehyde (BPF) and cellulose nanofibers (CNF) foams. These three areas of polymers are of particular interest due to their early stage of market adoption, yet significant industrial potential. As our focus is on construction materials, we will review their thermal, mechanical, and fire‐retardant performance, their synthesis/fabrication methods and future prospects. Improving the scalability, reproducibility and cost‐effectiveness of their production is vital for successful commercialization adoption.
... CNF production can involve a wide array of different operations (Fig. 10), resulting in a myriad of different CNF variants [229]. The general processing of cellulose to CNF involves sourcing the raw material (typically softwood/softwood pulp or hardwood/hardwood pulp), purification (typically via Kraft process or, sulfite process, and bleaching), mechanical pretreatment, biological/chemical pre-treatment (typically enzymatic, TEMPO-mediated carboxylation or sulfonation), principle mechanical treatment (typically refining, homogenization or grinding) and post-treatment [229,231,235]. ...
... As humidity increased, thermal conductivity initially decreased due to nanofibril swelling (increases inter-fibrillar distance, decreasing thermal boundary conductance) then increased sharply (at~70 % RH) as air displacement by water became the dominant effect As CNFs became thinner, moisture-dependent phonon scattering was enhanced, reducing thermal conductivity [235] Studied moisture uptake via simulations (hybrid Molecular Dynamic (MD) and Grand Canonical Monte Carlo (GCMC)) and experimental measurements at varying temperatures and relative humidity levels in cellulose films and foams composed of 1) TEMPOoxidized CNFs (TCNFs) and nanocrystals (TCNCs) 2) carboxymethylated CNFs (CMCNFs) ...
... A significant area of uncertainty related to the development of CNF foams is the effects of moisture on foam properties. As cellulose is naturally hygroscopic (due to the presence of hydroxyl surface groups), the thermal and mechanical properties of CNF foams can vary significantly during exposure to humid environments [235]. Thus, several studies have focused on quantifying and reducing the effects of moisture on CNF foam properties [235,255,259]. ...
... The moisture uptake by CNC is a phenomenon that depends on charge of ions, in this case gluconate, the Coulombic forces and weak Van der Waals forces. The higher acid concentration leads to smaller surface area, thus more chances of water uptake [26]. Moisture absorption of CNC is higher in comparison with MCC, might be due to more hydrophilic gluconate presence on the CNC surface. ...
Objective: The main objective of this work was to understand the basic properties of crystalline nanocellulose (CNC) that can be useful as a novel excipient in pharmaceutical formulations. This covers the isolation and preparation of nanocellulose followed by characterization. Methods: Cellulose was isolated from aquatic weed by autoclaving and bleaching. Cellulose to CNC conversion involved gluconic acid treatments at different concentrations (40%, 50% and 60%) followed by centrifugation and neutralization. CNC was further characterized by Differential Scanning Calorimetry (DSC) and Thermo gravimetric Analysis (TGA), Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscopy (AFM) for surface morphology, elemental analysis by Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), crystallinity index by X-Ray Diffraction (XRD), and optical microscopy. Results: Acid concentration affects the moisture uptake, particle size, and yield of CNC. CNC size ranged from 350 nm to 900 nm with a crystallinity index 80% to 85%. Moisture uptake was 6.38±0.12% at 33% relative humidity. DSC and TGA established thermal stability over 200 °C. Nanocellulose has shown Angle of repose (28.81°), Carrs index (12.32), zeta potential (33mV) values and heavy metals within pharmacopoeial limits. Conclusion: CNC from water hyacinth was prepared successfully by sustainable process. CNC physico-chemical characterization revealed the stable nature of CNC, suitable to be used as an excipient in pharmaceutical formulations.
... This could be explained by the addition of NCC which increased diffusional pathways for water uptake, thus reducing the water permeability of the bioplastic which resulted in the lower water absorption capacity [57]. A similar finding for the decrease in water absorption performance with crystalline cellulose has been reported by Garg et al. [58]. ...
The production and disposal of plastics have become a major global concern owing to its non-biodegradable properties in the environment. The recycling of apple biowaste as a value-added bioplastic precursor offers a solution to this waste disposal issue. In this study, readily available apple waste was converted into bioplastic through the delignification of cellulose cum reinforcement by nanocrystalline cellulose (NCC) extracted from the biowaste. The results indicated that the inclusion of apple waste and delignification effect had improved the bioplastic storage modulus (0.42–4.23 MPa) and brittleness in terms of hardness (5.22–0.51 kg). Morphological analysis revealed that the NCC had an average size of 70 nm and was homogeneously blended within the bioplastic matrix. The integration of the apple waste into the bioplastic promoted biodegradability, evident from the maximum weight loss of 58.1% after 4 weeks of biodegradation test, thus presenting a novel and alternative biodegradable plastic. The obtained results support apple waste as a potential filler for bioplastic development in food packaging, medical implants, 3D printing and water bottles.
Graphical Abstract
