Cellulose Iβ Research Articles

Effect of Titanium Dioxide Nanoparticle on Properties of Nanocomposite Membrane Made of Bacterial Cellulose

ABSTRACT The purpose of this study was to see the effect of adding TiO2 nanoparticles had on the characteristics of bacterial nanocellulose (BNC)-based membranes. Pellicles were created from the pineapple peel waste extract, and to obtain BNC, pellicle was disintegrated in six cycles using high-pressure homogenizer at 150 bar. The concentrations of TiO2 nanoparticles in the membrane reinforcement solution were 0.5, 1.0, 1.5, 2.0, and 2.5 wt.%. They were sonicated and dried in an oven at 60°C for 8 h. X-ray diffraction, Fourier transform infrared spectroscopy, roughness test, mechanical properties, and scanning electron microscopy were investigated to explore its claims. The results revealed that diffraction pattern of BNC/TiO2 membrane has a new peak at 25.05° that ensures the presence of TiO2 nanoparticles as well as diffraction peak occurred at 22.49°, which indicates the presence of cellulose Iβ. Moreover, the addition of TiO2 nanoparticles until 1.5 wt.%, the crystallinity index is relatively same and the optimum strength of 99.5 MPa was attained. Further, improvement in addition of TiO2 nanoparticle at 2 wt.% showed a decline in crystallinity index as 80.16% to 74.72% at 2.5 wt.%. The morphology of the membrane surface revealed that TiO2 nanoparticles were still agglomerated and not equally distributed across the BNC membrane, leading to increase in surface roughness.

Extraction and Characterization of Cellulose from Agricultural Residues: Wheat Straw and Sugarcane Bagasse

Wheat straw and Sugarcane bagasse are agricultural as well as industrial wastes rich in lignocellulosic components that can be extracted easily and used as a renewable source of energy. The main aim of this present work was to explore the alternative source of cellulose extraction using simple, fast, and eco-friendly conditions. The process involves NaOH degradation, acid hydrolysis, and bleaching using hydrogen peroxide as a bleaching agent. The extracted compound was analyzed by XRD and FTIR techniques. The XRD peaks obtained were specific to cellulose Iβ which is a crystalline allomorph with a monoclinic structure. The crystallite size of cellulose obtained from sugarcane bagasse was 10.51 nm which is larger than the size of cellulose obtained from wheat straw i.e 4.04 nm. Cellulose from sugarcane bagasse showed a crystallinity index of 51.84 % whereas wheat straw showed only 17.94 %. The yield was slightly higher in wheat straw than in sugarcane bagasse. FTIR analysis in sugarcane bagasse showed a characteristic peak at 3255.84 cm-1 which is shifted to 3340 cm-1 in the case of wheat straw. This peak is due to the vibration of the –OH group in both of the materials. However, both of the materials showed the vibration of the C-O-C bond at 1033 cm-1.

Molecular Insight into the Self-Assembly Process of Cellulose Iβ Microfibril.

The self-assembly process of β-D-glucose oligomers on the surface of cellulose Iβ microfibril involves crystallization, and this process is analyzed herein, in terms of the length and flexibility of the oligomer chain, by means of molecular dynamics (MD) simulations. The characterization of this process involves the structural relaxation of the oligomer, the recognition of the cellulose I microfibril, and the formation of several hydrogen bonds (HBs). This process is monitored on the basis of the changes in non-bonded energies and the interaction with hydrophilic and hydrophobic crystal faces. The oligomer length is considered a parameter for capturing insight into the energy landscape and its stability in the bound form with the cellulose I microfibril. We notice that the oligomer–microfibril complexes are more stable by increasing the number of hydrogen bond interactions, which is consistent with a gain in electrostatic energy. Our studies highlight the interaction with hydrophilic crystal planes on the microfibril and the acceptor role of the flexible oligomers in HB formation. In addition, we study by MD simulation the interaction between a protofibril and the cellulose I microfibril in solution. In this case, the main interaction consists of the formation of hydrogen bonds between hydrophilic faces, and those HBs involve donor groups in the protofibril.

Critical Evaluation of Reactive Force Fields for Vibrational Spectra: Case Study of Crystalline Cellulose Iβ

AbstractLattice dynamical calculations based on atomic potentials are used in the study of energetic materials for vibrational spectra. Features in the potential energy surface, however, can lead to negative eigenvalues of the dynamical matrix which can signify artifactual underlying dynamic or configurational instabilities or underconvergence. In this paper, using crystalline cellulose Iβ as a representative material, we show that a reactive force field (ReaxFF) necessarily yields structures associated with negative eigenvalues. We then propose a modification through a tapering function to eliminate barriers to potential energy minimization and thereby yield structures with no associated negative eigenvalues. Three particular ReaxFF parameterizations are evaluated with the tapering modification by comparing available electronic structure and experimental results from the literature. The newly minimized structures were evaluated using lattice properties, elastic constants, phonon dispersion, temperature‐dependent entropy, and heat capacity. Though the modification allows the models to produce only non‐imaginary vibrational spectra, the variations in computed properties can be large between the parameterizations, especially for those being used outside of the context for which the parameters were developed. Our calculations provide important information for the study of the phonon properties of molecular crystals such as cellulose and energetic materials.

Hirshfeld surface analysis of the intermolecular interaction networks in cellulose Iα and Iβ

Due to the high crystallinity and natural abundance, the crystal structures of native cellulose allomorphs have been theoretically studied until today, but some details remain to be deciphered. In this work, research was extended on the visualization and quantification of intermolecular interactions related to hydrogen bonds and van der Waals interactions in cellulose crystals Iα and Iβ based on previous studies. For each allomorph, the crystal structure has been described by two models of hydrogen bonding networks designated here as (A) and (B). This network diversity is due to the location of the hydrogen atoms of two disordered positions in the hydroxyl groups O6 and O2. Hirshfeld surface analysis (3D) was used to visualize the fidelity of intermolecular interactions O–H⋯O (involving O2 and O6) in the different cellulosic structural models Iα and Iβ. Two-dimensional fingerprint plots were used to identify the individual type of intermolecular contact and its impact on crystal packaging by graphical representation. A crystal contact study using the enrichment ratio was performed to investigate the tendency of intermolecular interactions to form the crystalline packing. The control of O–H⋯O inter-chain interactions in each type of network shows that hydrogen bonding is more favored in the model (A) than in the model (B).

Preparation of Cellulose Nanocrystals from Jujube Cores by Fractional Purification.

Jujube cores are fiber-rich industrial waste. Dewaxing, alkali treatment, bleaching, and sulfuric acid hydrolysis were used to generate cellulose nanocrystals (CNCs) from the jujube cores in this study. The morphological, structural, crystallinity, and thermal properties of the fibers were investigated using FE-SEM, TEM, AFM, FT-IR, XRD, and TGA under various processes. CNCs’ zeta (ζ) potential and water contact angle (WAC) were also investigated. The findings demonstrate that non-fibrous components were effectively removed, and the fiber particles shrunk over time because of many activities. CNCs had a rod-like shape, with a length of 205.7 ± 52.4 nm and a 20.5 aspect ratio. The crystal structure of cellulose Iβ was preserved by the CNCs, and the crystallinity was 72.36%. The temperature of the fibers’ thermal degradation lowered during the operations, although CNCs still had outstanding thermal stability (>200 °C). Aside from the CNCs, the aqueous suspension of CNCs was slightly agglomerated; thus, the zeta (ζ) potential of the CNCs’ suspension was −23.72 ± 1.7 mV, and the powder had high hydrophilicity. This research will be valuable to individuals who want to explore the possibility for CNCs made of jujube cores.

Morphological, UV blocking, and antimicrobial features of multifunctional cotton fibers coated with ZnO/Cu via sonochemistry

Multifunctional textiles have been quoted as a technologically and economically viable alternative to prevent the contamination and proliferation of microorganisms, increasing biomedical devices' safety by combining different properties with antimicrobial activities. The present work applied ultrasound waves to coat cotton fibers with ZnO and copper nanoparticles, using citric acid as an eco-friendly reductant/binder agent with different concentrations. We evaluated the cellulose morphology change caused by the surface treatment and the modification impact on different properties of cotton fibers using X-ray Diffractometry (XRD), Fourier-Transform Raman Spectroscopy (FT-Raman), colorimetry, Scanning Electron Microscopy (SEM), agar diffusion tests, and uniaxial tensile tests. The surface functionalization caused significant changes in the properties of the cotton fibers, including the relative proportions of cellulose Iβ and II, present in the cotton fibers, as demonstrated by the Rietveld refinement using X-ray diffractogram data. The multifunctional fibers are effective against Escherichia coli under photoirradiation, indicating that ROS generation is the most responsible mechanism for the bactericidal properties of the fibers. The sonochemical treatment present here is suitable for developing fabrics with multiple functional capacities, such as antimicrobial properties and UV blocking, using renewable sources.

Morphology, composition and structure of the fibers of a Chimu culture textile

In this work we studied the microfibers of a textile (T-shirt) of the Chimú culture. This culture developed on the northern coast of Peru. To determine the raw material and structural quality of the microfibers, the results of the Chimú textile were compared with the corresponding results for the microfibers of cotton from the northern coast of Peru (native cotton). Scanning electron microscopy images revealed that the Chimú textile yarns are composed of a set of interwoven microfibers. Energy dispersive X-ray spectroscopy and pulsed laser-induced plasma spectroscopy techniques allowed the identification of characteristic cellulose atoms in the microfibers of Chimú textile and native cotton. Only for the Chimú textile, these spectroscopic techniques allowed the identification of atoms corresponding to natural dyes and powder residues. Attenuated total reflection Fourier transform infrared spectroscopy identified the same molecular bonds for the microfibers of Chimú textile and native cotton. For the microfibers of Chimú textile and native cotton, the X-ray diffractograms showed peaks characteristic of the cellulose Iβ polymorphism of of monoclinic P21 structure. The raw material of the Chimú textile is cotton and the microfibers of this material show significant structural stability.

Stepwise allomorphic transformations by alkaline and ethylenediamine treatments on bamboo crystalline cellulose for enhanced enzymatic digestibility

Efficient modification and decrystallization of cellulose Iβ in lignocellulosic biomass are potential ways to overcome biomass recalcitrance and facilitates enzymatic degradation. Herein, we have treated moso bamboo and microcrystalline cellulose separately by either alkali or ethylenediamine (EDA) treatments, as well as using both in succession. The pretreatments successfully transformed the initial cellulose Iβ allomorph into cellulose II, IIII, and cellulose IIIII. Crystal structures and crystallinities were determined by Rietveld X-ray diffraction and CP/MAS 13C NMR. Comparatively, the samples that were sequentially treated by EDA and NaOH had low crystallinity (~50%), larger d-spacings of ~4.4 Å for the hydrophobic (110) planes, and less condensed microfibrillar aggregation. The factors simultaneously contributed to as high enzymatic hydrolysis yield as 89.5% and 91.7% respectively, followed by the yields of mercerized cellulose II and cellulose IIIII allomorph. The stepwise allomorphic transformations may provide new strategies on improving efficiency of saccharification process and biomass utilization.

Influence of Temperature on the Properties of Cellulose Iβ based on Molecular Dynamics Simulations

Natural plants, such as cotton and linen, are rich in cellulose Iβ. The properties of cellulose Iβ under different temperatures was studied using molecular dynamics simulations. Firstly, the crystal of cellulose Iβ was built. To verify the model, the X-ray fibre diffraction and thermal expansion coefficients were calculated, which were found to agree with experimental results. Then the Mulliken population of the bonds were computed and the movement of the centre chain and hydrogen bonds studied over the range 300-550 K using a PCFF force field. The results of the Mulliken population reveal the three steps of pyrolysis. The higher the temperature is, the more intensely the movement of the centre chain is. However, the impact of temperature on the movement of the centre chain is not obvious. From 300 K to 550 K, the total number of hydrogen bonds decreased by only 20%. Moreocer, the rupture of intrachain hydrogen bonds and the formation of interchain hydrogen bonds at 400 K ~ 450 K temperature occurred.

Morphology of Nanometric Overlayers Made of Porphyrin-Type Molecules Physisorbed on Cellulose Iβ Crystals and Nanocrystals.

Molecular dynamics simulations based on an atomistic empirical force field have been carried out to investigate structural, thermodynamic, and dynamical properties of adlayers made of porphyrin-type molecules physisorbed on surfaces of cellulose Iβ nanocrystals. The results show that low-index surfaces provide a thermally stable, weakly perturbing support for the deposition of non-hydrogen-bonded organic molecules. At submonolayer coverage, the discoidal porphyrin molecules lay flat on the surface, forming compact 2D clusters with clear elements of ordering. The adlayer grows layer-by-layer for the smallest porphyrin species on compact cellulose surfaces, while forming 3D clusters on a first relatively ordered adlayer (Stranski–Krastanov growth) in all other cases. The adsorption energy exceeds ∼1 eV per molecule, underlying the thermal stability of the adsorbate. Entropy plays a non-negligible role, destabilizing to some extent the adlayer. The in-plane dynamics of the smallest porphyrin species, i.e., porphine, on compact surfaces shows signs of superlubricity, due to the low energy and momentum exchange between the flat admolecule and the equally flat cellulose surface.

Characterization of Natural Cellulosic Fiber from Coccinia Grandis Root

ABSTRACT Adapting a sustainable and ecofriendly material system needs strategic induction of viable natural material. Toward this mission, a potential plant fiber, Coccinia grandis root fiber (CGRF), was characterized extensively to utilize as reinforcement in composites. The polarized light microscopy and SEM micrograph images of CGRF revealed a porous xylem and a thin primary cell wall, whereas the secondary cell walls are thick and lumens are wide. The fiber density was low at 1.29 ± .005 g/cm3 with a cross-sectional area of .01408 ± .00352 mm2. The existence of Iβ cellulose with 54.31% crystallinity index (CI) in CGRF was exhibited through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) studies. Tensile tests revealed that tensile strength and Young’s modulus of CGRF were around 710 MPa and 12 GPa respectively. The thermo-gravimetric inspection assured the thermal steadiness of CGRFs until 280°C, which was sufficient enough to withstand the polymerization process, which is an intended application of this fiber.

Solvent behavior of an ionic liquid set around a cellulose Iβ crystallite model through molecular dynamics simulations

Solvent behavior of an ionic liquid set around a cellulose Iβ crystallite model through molecular dynamics simulations

Molecular dynamics of dissolution of a 36-chain cellulose Iβ microfibril at different temperatures above the critical pressure of water

The cellulose dissolution is an essential pretreatment process for the chemical conversion of lignocellulosic biomass into biofuels. Here, the dissolution of a 36-chain Iβ cellulose model with a hexagonal cross-section (M36HCS) in water is analyzed by Molecular Dynamics (MD) with CHARMM36/TIP3P (C36/TIP3P) force field using gradual heating at 25 MPa. Our simulations showed that the dissolution of M36HCS starts to occur between 560 K and 600 K, which agrees with experimental observations. In our system, conditions near the critical point of water reveal that translational and rotational entropies decrease, while the low hydration level increases vibrational entropy. This investigation theoretically shows that C36/TIP3P adequately reproduces the dissolution of M36HCS even in high-pressure water as corroborated in reactors.

Time-Dependent Elastic Tensor of Cellulose Nanocrystal Probed by Hydrostatic Pressure and Uniaxial Stretching.

The elastic properties of crystals are fundamental for structural material. However, in the absence of macroscopic single crystals, the experimental determination of the elastic tensor is challenging because the measurement depends on the transmission of stress inside the material. To avoid arbitrary hypotheses about stress transfer, we combine hydrostatic pressure and uniaxial-stretching experiments to investigate the elastic properties of cellulose Iβ. Three orthogonal compressibilities are 50.0, 6.6, and 1.71 TPa-1. Combining Poisson's ratios from a uniaxial stretching experiment directly gives the Young's modulus along the chain direction (E33). However, Poisson's ratio depends on the deformation rate leading to apparent modulus E33 = 113 GPa using a slow cycle (hours) and 161 GPa using a fast cycle (minutes). The lattice deformation along the chain is not time-dependent, so the off-diagonal elements are time-dependent on the scale of minutes to hours.

Structure, thermal stability and electrical properties of cellulose‐6‐phosphate: development of a novel fast Na‐ionic conductor

AbstractIn this study, alkali cellulose‐6‐phosphate (A‐CP) was prepared by the treatment of cellulose‐6‐phosphate (CP) with an aqueous solution of sodium hydroxide. X‐ray diffraction and Fourier transform infrared, 13C NMR, 31P NMR and 23Na NMR spectroscopies were used to characterize the studied polymers. CP and A‐CP crystallize in the monoclinic system of the P21 space group (cellulose Iβ). CP and A‐CP, with relative densities of 70% and 77%, respectively, were shaped into cylindrical pellets by uniaxial pressing and sintering at 423 K of A‐CP. Electrical conductivity measurements of CP and A‐CP were carried out using complex impedance spectroscopy between 298 and 433 K in the frequency range 5 Hz to 13 MHz. The influence of aqueous NaOH on the structure, thermal stability and electrical conductivity of cellulose phosphate was observed. In contrast to CP, A‐CP was stable up to temperatures exceeding 433 K and showed fast ionic conductivity σ393K = 2.03 × 10−6 S cm−1 with an activation energy of 0.73 eV. © 2021 Society of Chemical Industry

Influence of Fine Structure on the Variations of Thermal and Mechanical Properties in Flax Fibers Modified with Different Alkaline Treatment Conditions

ABSTRACT The alkaline treatment condition plays a crucial role in governing the ultimate properties of flax fibers. In this study, flax fibers were modified with mild alkalization and severe mercerization conditions to give fundamental insight into how the molecular-scale changes in cell wall fine structure and cellulose supramolecular structure can affect the macroscopic properties of fibers. SEM, FTIR, XRD, TGA, and DSC techniques were employed to characterize the variations in morphology, composition, crystalline structure, and thermal properties of fibers. Also, tensile tests evaluated their reinforcing performance in polypropylene-based composites. The results indicated that alkalization in 5% (w/v) NaOH solution preserved the tensile properties of fibers, shifted their thermal decomposition temperature from 198 to 254°C, and effectively decreased their moisture absorption content by 18%. The improvements primarily originate from the partial removal of noncellulosic constituents and promoted crystallinity of native cellulose Iβ structure. However, mercerization in 20% (w/v) solution significantly reduced the rigidity of fibers in the longitudinal direction. Furthermore, it decreased the moisture absorption only by 6% and shifted the thermal degradation to 275°C. The excessive elimination of noncellulosic constituents and the polymorphic transformation, which led to a weaker hydrogen bonding network in the cellulose II region, accounts for these changes.

Valorization of khat (Catha edulis) waste for the production of cellulose fibers and nanocrystals.

Cellulose fibers (C40 and C80) were extracted from khat (Catha edulis) waste (KW) with chlorine-free process using 40% formic acid/40% acetic acid (C40), and 80% formic acid/80% acetic acid (C80) at the pretreatment stage, followed by further delignification and bleaching stages. Cellulose nanocrystals (CNCs40 and CNCs80) were then isolated from C40 and C80 with sulfuric acid hydrolysis, respectively. Thus, the current study aims to isolate cellulose fibers and CNCs from KW as alternative source. The KW, cellulose fibers, and CNCs were investigated for yield, chemical composition, functionality, crystallinity, morphology, and thermal stability. CNCs were also evaluated for colloidal stability, particle size, and their influence on in vitro diclofenac sodium release from gel formulations preliminarily. The FTIR spectra analysis showed the removal of most hemicellulose and lignin from the cellulose fibers. The XRD results indicated that chemical pretreatments and acid hydrolysis significantly increased the crystallinity of cellulose fibers and CNCs. The cellulose fibers and CNCs exhibited Cellulose Iβ crystalline lattice. TEM analysis revealed formation of needle-shaped nanoscale rods (length: 101.55–162.96 nm; aspect ratio: 12.84–22.73). The hydrodynamic size, polydispersity index, and zeta potential of the CNCS ranged from 222.8–362.8 nm; 0.297–0.461, and -45.7 to -75.3 mV, respectively. CNCs40 exhibited superior properties to CNCs80 in terms of aspect ratio, and colloidal and thermal stability. Gel formulations containing high proportion of CNCs sustained diclofenac sodium release (< 50%/cm2) over 12 h. This study suggests that cellulose fibers and nanocrystals can be successfully obtained from abundant and unexploited source, KW for value-added industrial applications.

Cell wall configuration and ultrastructure of cellulose crystals in green seaweeds

Green seaweeds (Chlorophyta) are often considered a nuisance, but may in fact constitute a potential climate-friendly renewable resource in the new bioeconomy. Utilization of green seaweed polysaccharides could in particular enable a new type of green growth in coastal regions in developing countries e.g. in West Africa. The carbohydrate constituents, including cellulose, are lignin-free, but only limited knowledge is available on the cellulose ultrastructure and cellulose crystallinity in commonly occurring green seaweeds. Abundantly available green seaweeds along the coast in West Africa include Chaetomorpha linum, Caulerpa taxifolia, Ulva fasciata and Ulva flexuosa. Here, using X-ray diffraction (XRD), on cellulose gently purified from the green seaweeds, we determined that mainly cellulose Iα was present in both C. linum and U. flexuosa. We also found that the crystallite diameter was particularly large, 16 nm, in both the Ghanaian and the Danish C. linum samples, especially compared to the crystallite diameter of 2.5–5 nm in most terrestrial vascular plants (Tracheophytes), which mainly contain cellulose Iβ. For U. flexuosa, increasing crystallinity of the cellulose was achieved during purification. Cellulose purification was not achievable for C. taxifolia, indicating that in this species the glucose is mainly a constituent of other carbohydrates, presumably notably of starch. Transmission electron microscopy (TEM) confirmed the large size of the crystallites of C. linum showing the cellulose forming a multi-lamellar structure with alternating perpendicular and parallel layers along the fibre axis. The cell wall nano-structure appeared amorphous in C. taxifolia and as a network in U. fasciata and U. flexuosa. As glucose was most abundant in C. linum and its cellulose was crystalline, this green seaweed species appears particularly promising as a source for manufacturing of novel cellulose-based materials, e.g. specialized paper or cellulose-based composite materials.

Humidity-Dependent Thermal Boundary Conductance Controls Heat Transport of Super-Insulating Nanofibrillar Foams

Summary Cellulose nanomaterial (CNM)-based foams and aerogels with thermal conductivities substantially below the value for air attract significant interest as super-insulating materials in energy-efficient green buildings. However, the moisture dependence of the thermal conductivity of hygroscopic CNM-based materials is poorly understood, and the importance of phonon scattering in nanofibrillar foams remains unexplored. Here, we show that the thermal conductivity perpendicular to the aligned nanofibrils in super-insulating ice-templated nanocellulose foams is lower for thinner fibrils and depends strongly on relative humidity (RH), with the lowest thermal conductivity (14 mW m−1 K−1) attained at 35% RH. Molecular simulations show that the thermal boundary conductance is reduced by the moisture-uptake-controlled increase of the fibril-fibril separation distance and increased by the replacement of air with water in the foam walls. Controlling the heat transport of hygroscopic super-insulating nanofibrillar foams by moisture uptake and release is of potential interest in packaging and building applications.