Amounts Of Cellulose Nanocrystals Research Articles

Tannic acid adsorption properties of cellulose nanocrystalline/fish swim bladder gelatin composite sponge

Foods and beverages with excessive tannins acid (TA) content taste astringent and bitter. The overconsumption of TA could result in nutritional and digestive problems. In this study, the cellulose nanocrystals (CNC)/fish swim bladder gelatin (FG) composite sponge was prepared with glutaraldehyde as a crosslinking agent. The TA adsorption performance of the sponge was discussed. The freeze-dried CNC/FG composite sponge had a porous network structure. CNC was combined into the FG matrix as a reinforcing phase. The mechanical strength, thermal stability, and swelling properties of the composite sponge were improved with the addition of an appropriate amount of CNC. Although CNC decreased the porosity of composite sponge, the increase in active adsorption sites resulted in an overall positive effect on its TA adsorption properties. Under the optimal adsorption conditions, the TA removal rate of 1.0 % CNC composites reached 80.4 %. Furthermore, the sponge retained a TA removal rate of 54 % after five cycles of adsorption and desorption using 50 % ethanol. The results demonstrated that CNC/FG composite sponge has application potential in the field of adsorption materials for TA.

Response surface optimization of process parameters for preparation of cellulose nanocrystal stabilized nanosulphur suspension

This study employed response surface methodology (RSM) to optimize various parameters involved in the synthesis of nanosulphur (NS) stabilized by cellulose nanocrystals (CNCs). The elemental sulphur (ES) mixed with CNCs was processed in a high-pressure homogenizer to make a stable formulation of CNC-stabilized NS (CNC-NS). RSM was adopted to formulate the experiments using Box-Behnken design (BBD) by considering three independent variables i.e., ES (5, 10, 15 g), CNCs (25, 50, 75 ml), and the number of passes (NP) in the high-pressure homogenizer (1, 2, 3). For the prepared suspensions (CNC-NS), the range of the responses viz. settling time (0.84–20.60 min), particle size (500.41–1432.62 nm), viscosity (29.20–420.60 cP), and surface tension (60.35–73.61 N/m) were observed. The numerical optimization technique was followed by keeping the independent and dependent factors in the range yielded in the optimized solution viz. 46 ml (CNCs), 8 g (ES), and 2 (NP). It was interpreted from the findings that the stability of the suspension had a positive correlation with the amount of CNC while the increasing proportion of ES resulted in reduced stability. The quadratic model was fitted adequately to all the responses as justified with the higher coefficient of determination (R2 ≥ 0.88). The characterization performed by X-ray diffraction (XRD), zeta potential, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR) revealed better-stabilizing properties of the optimized CNCs–ES suspension. The study confirmed that CNCs have the potential to be utilized as a stabilizing agent in synthesizing stable nanosulphur formulation by high-pressure homogenization.

Cellulose rubber foam composite use as oil absorbent

The focus of this study was to explore the fabrication of cellulose rubber foam (CRF) using kapok fibers (KF) as an oil absorbent material. Chemical methods such as sodium hydroxide surface treatment, hydrogen peroxide treatment, and acid hydrolysis were employed to prepare cellulose nanocrystals (CNC). The results of the nuclear magnetic resonance (NMR) spectroscopy test indicated that the chemical modification of kapok fiber resulted in the removal of lignin and hemicellulose by a disappearing peak at 17, 52, and 148 ppm, respectively. Hydrolysis process of the kapok fiber resulted in nanometer-sized cellulose, with a yield of 72% as revealed by transmission electron microscopy (TEM). The amount of cellulose nanocrystals from kapok fiber (KF-CNC) used in the study varied from 0 to 5 phr during the formation of the cellulose rubber foam, and it was found that the foam density increased as the number of cellulose nanocrystals from kapok fiber increased. Additionally, the percentage of collapse from the compressive strength of cellulose rubber foam decreased as the amount of cellulose nanocrystals from kapok fiber increased. Fourier transform infrared spectroscopy (FTIR) confirmed the incorporation of cellulose nanocrystals from kapok fiber into the rubber foam (RF) as the amount of cellulose nanocrystals from kapok fiber increased. The oil absorbent of cellulose rubber foam composite with 1 phr cellulose nanocrystals from kapok fiber show highest absorption capacity was 17.8 g/g. The cellulose rubber foam composite absorbs oil before absorbing water when water and oil are combined. Moreover, the cellulose rubber foam could be reused more than 50 times.

Modification mechanism of cellulose nanocrystals in cement

To investigate the modification mechanism of cellulose nanocrystals (CNCs) in cement, this paper simplifies the complex cement system to pure tricalcium silicate (C3S) mineral components. The hydration characteristics of C3S mixed with different amounts of CNCs and the chemical environment of the hydration products were explored. CNCs have a similar effect to superplasticizers in reducing the hydration exothermic. The addition of CNCs promotes the growth of Ca(OH)2 on the (001) crystal plane and increases the grain size of Ca(OH)2. CNCs provide additional nucleation sites, which reduces the degree of polymerization and shortens the main chain length of the generated C-S-H. The separate-hydration test confirmed that the CNCs successively adsorbed calcium ions and silicate ions, which promoted the formation of C-S-H gel coating on the surface of CNCs. The elucidation of the modification mechanism of CNCs provides theoretical guidance for its application in cement.

Cellulose nanocrystals as sustainable additives in water-based cutting fluids

Cutting fluid is indispensable in the machining industry as a fluid for lubrication and cooling in the metalworking process due to their ability to significantly improve various properties of cutting fluid. Castor oil, as a common base oil and additive in cutting fluid, can be grafted onto the surface of cellulose nanocrystals (CNC) to further enhance the lubricating properties of cutting fluid. It has been shown that cellulose nanocrystals and castor oil modified cellulose nanocrystals (CO-CNC) as additives in cutting fluid have good dispersion stability and can effectively improve the lubricating properties. When the amount of CNC or CO-CNC was added in the working fluid at about 0.5 wt%, the friction coefficient was significantly reduced. According to the results from this study, cellulose nanocrystal is a promising candidate as the nontoxic and renewable additive for the improvement of diverse performances for the water-based cutting fluid.

Cellulose Nanocrystals Reinforced Zein/Catechin/β-Cyclodextrin Inclusion Complex Nanoparticles Nanocomposite Film for Active Food Packaging.

In this study, following the green, environmentally friendly and sustainable development strategy, cellulose nanocrystals (CNCs) were prepared through a solvent-free esterification reaction between microcrystalline cellulose and maleic anhydride, combined with subsequent ultrasonic treatment, and maleic-anhydride-modified CNC-reinforced zein/catechin/β-cyclodextrin inclusion complex nanoparticles nanocomposite films were prepared by a facile solution casting. The amount of CNCs in the film matrix was 0–8 wt%, and their effect on structural, physicochemical and functional properties of the resulting films were investigated. SEM images showed that the addition of CNCs made the microstructure of the film more smooth and uniform. The intermolecular hydrogen bonds between CNCs and film matrix were supported by FT-IR. XRD analysis also confirmed the appearance of a crystalline peak due to the existence of CNCs inside the films. The incorporation of CNCs significantly reduced water vapor permeability, water solubility and the swelling degree of the nanocomposite film, and also significantly increased tensile strength and elongation at break from 12.66 to 37.82 MPa and 4.5% to 5.2% (p < 0.05). Moreover, nanocomposite film packaging with CNCs can effectively inhibit the oxidation of soybean oil.

Cellulose Nanocrystals as Template for Improving the Crystallinity of Two-Dimensional Covalent Organic Framework Films.

Despite the rapid development of two-dimensional covalent organic frameworks (2D COFs) in recent years, it remains a great challenge to synthesize highly crystalline COF materials. Here, a CNC-assisted approach was adopted to synthesize high crystallinity COF materials. A series of 2D COF films were synthesized at the air–water interface by using cellulose nanocrystals (CNCs) as the template. The occurrence of Schiff reactions based on the imine bond was demonstrated by Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) exhibited the appearances of 2D COF films were flower-like. When CNCs were added to a certain extent, the size of a single petal in the flowers gradually increased with the amount of CNCs. The film with large petals was characterized by Ultraviolet–Visible diffuse reflectance spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). In UV–Vis DRS curves, the S-band of COF-366 film was red-shifted by 24 nm compared with that of 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin (TAPP), confirming the existence of extended conjugation in COF-366 film. XPS was used to identify the surface composition of the sample. The N1s signal of the film indicated that each TAPP formed four imine bonds with 2,5-dihydroxyterephthalaldehyde (DHTA) in COF-366 film. TEM images showed that CNCs had an influence on the crystal size. It was observed from SAED that the crystallinity of the film with CNCs was higher than the film without CNCs. This work provided a new template for improving the crystallinity of 2D COF films.

Multifunctional bioactive chitosan/cellulose nanocrystal scaffolds eradicate bacterial growth and sustain drug delivery

Chitosan-based hydrogels have received significant interest in tissue engineering and regenerative medicine applications owing to their superior biocompatibility. However, their applications are restricted owing to their weak mechanical strength. Cellulose nanocrystals (CNCs) are often explored as reinforcing agents to improve the native properties of polymers owing to their superior physicochemical properties. We fabricated a multi-functional hydrogel scaffold of chitosan/CNCs by incorporating different amounts of CNCs into a chitosan (CH) hydrogel. Significant enhancement in the mechanical strength was noted in the CH/CNCs as compared to that in pure CH hydrogel scaffolds. The cytocompatibility of the fabricated scaffolds was monitored in the presence of bone-marrow-derived mesenchymal stem cells (BMSCs). Improved cell viability and mineralization were observed with CH/CNC hydrogel scaffolds than those with pure CH hydrogel scaffolds. Enhanced osteogenic-related gene expression was observed in the CH/CNC hydrogel scaffold environment than that in the control, indicating their osteogenic potential, in addition to enhanced antibacterial activity. Developed composite scaffolds exhibited improved sustained drug release compared to that by pure polymer scaffolds, and this was more sustained in the scaffolds with higher CNC content. Therefore, the fabricated scaffolds may have been used in tissue engineering for osteogenesis, as antibacterial agents, and in sustained drug delivery.

Effect of Cellulose Nanocrystals Nanofiller on the Structure and Sorption Properties of Carboxymethyl Cellulose-Glycerol-Cellulose Nanocrystals Nanocomposite Systems.

Biobased materials present a great interest due to their properties and biodegradability. Cellulose nanocrystals (CNC) nanofiller, in various amounts, was incorporated into a carboxymethyl cellulose (CMC)–glycerol (G) matrix in order to obtain nanocomposite systems with improved properties. The effect of the nanofiller on the structural features was investigated by Fourier transform infrared (FT-IR) spectroscopy, principal component analysis (PCA), two-dimensional correlation spectroscopy (2D-COS), and X-ray diffraction, while the sorption properties were evaluated by water vapor isotherms using the gravimetric method coupled with infrared spectroscopy. We observed the presence of the interactions taking place between the CMC-G and CNC involving the hydroxyl and carboxylate groups, which decreased the number of water sorption sites. Following this, the moisture content in the nanocomposite films decreased with the increase in the amount of CNC. Moreover, the bands associated to water molecules presented different wavenumber values separated for CMC-G and CNC components.

Self-Healing Polyester Urethane Supramolecular Elastomers Reinforced with Cellulose Nanocrystals for Biomedical Applications.

Stretchable self-healing urethane-based biomaterials have always been crucial for biomedical applications; however, the strength is the main constraint of utilization of these healable materials. Here, a series of novel, healable, elastomeric, supramolecular polyester urethane nanocomposites of poly(1,8-octanediol citrate) and hexamethylene diisocyanate reinforced with cellulose nanocrystals (CNCs) are introduced. Nanocomposites with various amounts of CNCs from 10 to 50 wt% are prepared using solvent casting technique followed by the evaluation of their microstructural features, mechanical properties, healability, and biocompatibility. The synthesized nanocomposites indicate significantly higher tensile modulus (approximately 36-500-fold) in comparison to the supramolecular polymer alone. Upon exposure to heat, the materials can reheal, but nevertheless when the amount of CNC is greater than 10 wt%, the self-healing ability of nanocomposites is deteriorated. These materials are capable of rebonding ruptured parts and fully restoring their mechanical properties. In vitro cytotoxicity test of the nanocomposites using human dermal fibroblasts confirms their good cytocompatibility. The optimized structure, self-healing attributes, and noncytotoxicity make these nanocomposites highly promising for tissue engineering and other biomedical applications.

Cellulose nanocrystals-starch nanocomposites produced by extrusion: Structure and behavior in physiological conditions

Different amounts of cellulose nanocrystals (CNCs) were added to glycerol-plasticized thermoplastic starch (TPS) to obtain bio-based nanocomposites. First, nanocomposites are prepared by extrusion and their structure is studied at different scales using WAXS (Wide Angle X-ray Scattering) and solid-state NMR (Nuclear Magnetic Resonance) for local/crystalline organization, AF4 (Asymmetrical Flow Field-Flow Fractionation) for molecular weight and chain length, and SEM (Scanning Electron Microscopy) for the morphology at a larger scale. Then, relevant mechanical properties and behavior in physiological conditions (swelling, enzymatic degradation) are characterized. The results show that the incorporation of cellulose nanocrystals up to 2.5 wt% causes a mechanical reinforcement as determined by DMTA (Dynamic Mechanical Thermal Analysis) and reduces the swelling and the enzymatic degradation of the materials compared to reference TPS. This could be linked to the formation of starch-cellulose hydrogen and hydroxyl bonds. Conversely, above 5 wt% CNC content nanocrystals seem to aggregate which in turn worsens the behavior in physiological conditions.

Effect of cellulose nanocrystals on the performance of oil-immersed transformer insulating paper

The possibility of enhancing both mechanical and breakdown properties of oil-immersed transformer insulating paper were considered by introduction of cellulose nanocrystals (CNCs). Two kinds of CNCs were taken into account: the TEMPO-oxidized CNCs (T-CNC) and the sulfuric acid hydrolyzed CNCs (S-CNC). Insulating paper containing no CNCs was also prepared as a reference. Obtained samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The effects of different amounts of CNC on tensile strength, AC breakdown strength, oil absorption rate, and conductivity of insulating paper extract were studied. The CNC improved the mechanical and electrical performances of insulating paper, and the effect of T-CNC was a little better than that of S-CNC. When the T-CNC dosage was 0.9%, the tensile strength, AC breakdown strength in oil, and oil absorption rate of the insulating paper were 70.22 N • m/g, 59.8 kV/mm, and 53.1%, respectively, which was improved by 21.7%, 24.6%, and 39.4%, respectively, compared with the reference insulating paper. The beating degree of pulp also affected the mechanical and electrical properties of insulating paper containing CNC. Based on overall performance, it was concluded that CNCs are promising nano-additives for oil-immersed transformer insulating paper, especially for T-CNC.

Effect of cellulose nanocrystals on crystallization, morphology and phase transition of polyamide 6

ABSTRACTNanocomposites comprised of polyamide 6 (PA6) and cellulose nanocrystals (CNC) were prepared by solvent casting and subsequent melt pressing. The role of cellulose nanocrystals on morphology, crystallization and conformation of the resulting PA6 nanocomposites were investigated using differential scanning calorimetry, thermogravimetric analysis and Fourier transform infrared (FTIR) spectroscopy. Scanning electron microscopic observation showed that the CNC were homogenously dispersed in the PA6 nanocomposites up to 5 wt% CNC. The thermal stability of the PA6 nanocomposites slightly decreased with the CNC loading. The addition of the CNC modified the non-isothermal crystallization behavior of the PA6 nanocomposites by increasing the crystallization temperature and the rate of nucleation. FTIR spectroscopic observation showed that the neat PA6 primarily crystallized in the more stable α crystalline form and that an α to metastable γ crystalline transformation occurred with increasing concentrations of the CNC in the PA6 matrix. The non-isothermal crystallization kinetics of these nanocomposites with increasing CNC content were investigated, and it was demonstrated that the amount of CNC plays a significant role in crystallization kinetics.

Cellulose nanocrystals reinforced κ-carrageenan based UV resistant transparent bionanocomposite films for sustainable packaging applications

In this work, κ-carrageenan bionanocomposite films were prepared by solution casting of a mixture of κ-carrageenan, glycerol, and various amounts of cellulose nanocrystals (CNCs, 0–9 wt.%). The structure and morphology of the bionanocomposite films were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Compared with κ-carrageenan films, the κ-carrageenan bionanocomposite films showed better mechanical and barrier properties (water and UV) and thermal stability. The water contact angle increased from 23.30° to 71.80° and the water vapor permeation decreased from 8.93 gm−1 s−1 Pa−1 to 4.69 × 10−11 gm−1 s−1 Pa−1 in the κ-carrageenan films loaded with 9–7 wt.% CNCs, respectively. The tensile strength and elongation at break of the films increased from 38.33 ± 3.79 MPa to 52.73 ± 0.70 MPa and from 21.50 ± 3.72% to 28.27 ± 2.39%, respectively, after CNC loading increased from 0 wt.% to 7.0 wt.%. These results indicated that the κ-carrageenan nanocomposite films have potential applications in food packaging.

Synthesis and characterization of novel Cellulose Nanocrystals-based Thin Film Nanocomposite membranes for reverse osmosis applications

A novel TFN membrane was fabricated by embedding Cellulose Nanocrystals (CNCs) into the polyamide active layer. Membranes were synthesized by in-situ interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) containing different amounts of CNCs. Successful incorporation of CNCs into the polyamide layer was confirmed by XRD analyses. Surface morphology of the membranes was characterized by SEM and AFM. Water contact angle measurements showed improved hydrophilicity of the TFN membranes. Desalination experiments with synthetic brackish water at 20 bar(g) revealed doubling of the water flux from 30 to 63 ± 10 L/m2·h, without significantly compromising the salt rejection (97.8%) for 0.1% (w/v) CNCs loading. In the fouling/filtration experiments with 300 ppm of Bovine Serum Albumin (BSA) in the feed solution, the TFN membrane had 11% smaller water flux reduction compared to the control TFC membrane. The promising performance of the CNCs-based TFN membranes and the fact that CNCs are inexpensive and abundant nanoparticles indicates their potential for a large-scale use in water desalination. Moreover, since CNCs are safe and environmentally friendly nanoparticles their possible leaching out during membrane operation would not impose health and environmental concerns.

Effect of cellulose nanocrystals from sugarcane bagasse on whey protein isolate-based films

Whey protein isolate (WPI) has been utilized as edible film or food packaging material. However, WPI films are hydrophilic due to highly polar amino acids which provide a moderate barrier to water vapor and low mechanical properties. To overcome these drawbacks, cellulose nanocrystals (CNCs) extracted from sugarcane bagasse were incorporated with whey protein. FTIR and TGA were used to confirm the changes in chemical structures and to observe the thermal properties, respectively. The CNCs had sizes of 200–300 nm and diameters of 20–40 nm using TEM and AFM technique, respectively. Different amounts of CNCs (0–8 wt% based on WPI) were added into whey protein solution and formed films. The lightness and transparency of the films tended to decrease with increasing WPI content. The water activity (aw) and water solubility of those films increased, whereas their water contact angle values decreased, implying that the film became more hydrophilic when the cellulose nanocrystal was added. The addition of CNCs increased the tensile strength and Young's modulus and reduced the water vapor permeability of WPI-based CNC films. However, the CNCs did not change the oxygen permeability of the film. Therefore, the obtained WPI films provided good mechanical performance and may be promising as an alternative product for film packaging.

Development of sodium alginate-xanthan gum based nanocomposite scaffolds reinforced with cellulose nanocrystals and halloysite nanotubes

Sodium alginate (Alg) and xanthan gum (XG) based nanocomposite scaffolds reinforced with various amounts of cellulose nanocrystals (CNCs) and/or halloysite nanotubes (HNTs) were prepared by freeze-casting/drying method. In this study, the structure-property-performance relationship was mainly focused and analysed. Morphological analysis showed high porosity and pore-interconnectivity (pore channels) in all obtained scaffolds. Structural analysis demonstrates the good interfacial interactions and uniform dispersion of the CNCs and HNTs, involving partial orientation within the polymeric network. The water uptake capacity (from 14.73.7 ± 0.46 g/g to 11.34 ± 0.32 g/g) and porosity (from 91.7 ± 0.81% to 88.5 ± 0.64%) were reduced. The compressive strengths (in dry state from 91.1 ± 1.2 kPa to 114.4 ± 0.6 kPa and in wet state from 9.0 ± 0.8 kPa to 10.6 ± 0.8 kPa), thermal stability, cytocompatibility (MC3T3-E1 osteoblastic cells) of the nanocomposite scaffolds improved as compared to Alg and AlgX scaffolds without CNCs and/or HNTs. The obtained scaffolds may be appropriate as scaffolding material in bone tissue engineering.

Polylactide/cellulose nanocrystals: The in situ polymerization approach to improved nanocomposites

The in situ polymerization of l-lactide in the presence of various amounts of cellulose nanocrystals (CNC) is described. CNC was prepared efficiently by acidic hydrolysis of cotton linters. Molecular weight, morphology, thermal, mechanical and crystallization properties of the PLA-CNC nanocomposites were evaluated. From size-exclusion chromatography (SEC) analysis, the actual occurrence of chemical bond between CNC and PLA can be assessed. The effect of CNC has been evaluated through differential scanning calorimetry (DSC) analysis, which highlights the probable formation of α′ crystals in the obtained materials. More importantly, from thermogravimetric analysis (TGA) a marked improvement in thermal stability of nanocomposites has been demonstrated, with respect to standard PLA and to previously described PLA-CNC blends. Nanocomposites show also an improvement in rheological properties with respect to standard PLA. In particular, storage modulus greatly increases, indicating a reinforcing effect of CNC. The described in situ synthetic methodology allows an optimal compatibilization between the two entities (PLA and CNC), facing one of the major problems inherent to the preparation of nanocomposites. It leads furthermore to remarkably improved thermal and rheological properties of the obtained materials.

Biodegradable Composite Films based on κ-carrageenan Reinforced by Cellulose Nanocrystal from Kenaf Fibers

Through alkali treatment, bleaching, and sulfuric acid hydrolysis, cellulose nanocrystals (CNCs) were prepared from kenaf fibers and were used as reinforcement materials in biocomposites based on κ-carrageenan. Biocomposites in the form of films were prepared by solution casting of a mixture of κ-carrageenan, glycerol, and various amounts of CNCs (0 to 8 wt%). Fourier transform infrared spectroscopy (FTIR) revealed that alkali treatment followed by bleaching totally removed lignin and hemicellulose from the kenaf. Morphological analysis of the fibers, cellulose, and κ-carrageenan of biocomposite films were carried out using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The effects of filler content on the mechanical and thermal stability of the k-carrageenan biocomposite films were analyzed through tensile strength measurements and thermogravimetric analysis (TGA). At an optimum CNC content of 4%, the κ-carrageenan biocomposite films showed good dispersion, superior mechanical properties, and improved thermal stability.

Preparation and Characterization of Pol(vinyl Alcohol）/ Cellulose Nanocomposites

In this study, nanocomposite membranes were prepared from poly (vinyl alcohol) (PVA) with different amounts of cellulose nanocrystals as filler and characterized by thermogravimetry (TG). Swelling sorption behavior of various feed alcohol mixtures was investigated at 80°C, and found that NCC in PVA matrix could help to reduce the overall membrane swelling. Mechanical properties of the nanocomposite membranes were examined in relation to NCC content in the composite. Optimal NCC content in the composite was found to be 3 wt% in terms of its overall properties as compared to neat PVA film. With the addition of 3 wt% NCC to PVOH the ultimate tensile strength showed improvement compared to pure PVA. The PVA/ NCC nanocomposite membrane had shown increases in elongation at low filler loadings. The TG analysis demonstrated that the nanocomposite membranes exhibited higher thermal resistance.