Addition Of Cellulose Nanocrystals Research Articles

Complexation between rice starch and cellulose nanocrystal from black tea residues: Gelatinization properties and digestibility in vitro

In this work, cellulose nanocrystal (CNC) was extracted from black tea waste and its effects on the physicochemical properties of rice starch were explored. It was revealed that CNC improved the viscosity of starch during pasting and inhibited its short-term retrogradation. The addition of CNC changed the gelatinization enthalpy and improved the shear resistance, viscoelasticity, and short-range ordering of starch paste, which meant that CNC made the starch paste system more stable. The interaction of CNC with starch was analyzed using quantum chemistry methods, and it was demonstrated that the hydrogen bonds were formed between starch molecules and the hydroxyl groups of CNC. In addition, the digestibility of starch gels containing CNC was significantly decreased because CNC could dissociate and act as an inhibitor of amylase. This study further expanded the understanding of the interactions between CNC and starch during processing, which could provide a reference for the application of CNC in starch-based foods and the development of functional foods with a low glycemic index.

The Fabrication of Gelatin-Elastin-Nanocellulose Composite Bioscaffold as a Potential Acellular Skin Substitute.

Gelatin usage in scaffold fabrication is limited due to its lack of enzymatic and thermal resistance, as well as its mechanical weakness. Hence, gelatin requires crosslinking and reinforcement with other materials. This study aimed to fabricate and characterise composite scaffolds composed of gelatin, elastin, and cellulose nanocrystals (CNC) and crosslinked with genipin. The scaffolds were fabricated using the freeze-drying method. The composite scaffolds were composed of different concentrations of CNC, whereas scaffolds made of pure gelatin and a gelatin-elastin mixture served as controls. The physicochemical and mechanical properties of the scaffolds, and their cellular biocompatibility with human dermal fibroblasts (HDF), were evaluated. The composite scaffolds demonstrated higher porosity and swelling capacity and improved enzymatic resistance compared to the controls. Although the group with 0.5% (w/v) CNC recorded the highest pore size homogeneity, the diameters of most of the pores in the composite scaffolds ranged from 100 to 200 μm, which is sufficient for cell migration. Tensile strength analysis revealed that increasing the CNC concentration reduced the scaffolds' stiffness. Chemical analyses revealed that despite chemical and structural alterations, both elastin and CNC were integrated into the gelatin scaffold. HDF cultured on the scaffolds expressed collagen type I and α-SMA proteins, indicating the scaffolds' biocompatibility with HDF. Overall, the addition of elastin and CNC improved the properties of gelatin-based scaffolds. The composite scaffolds are promising candidates for an acellular skin substitute.

Cellulose Nano Crystals (CNC) as Additive for a Bio-Based Waterborne Acrylic Wood Coating: Decay, Artificial Weathering, Physical and Chemical Tests.

Wood coatings prolong the service life of wood-based products, but they are usually of synthetic origin. The aim of the present article is to reduce the fossil-based compounds in a commercial waterborne acrylic coating by CNC addition and to test its performance. The coatings were applied on European beech and Norway spruce wood in order to test durability against Gloeophyllum trabeum (brown wood rot) and Trametes versicolor (white wood rot). Artificial weathering and blue stain, contact angle, physical tests (adhesion, impact and scratch test), chemical (FTIR) and morpho-anatomical analysis (SEM) were carried out. CNC addition increased viscosity, limiting the spreading of the coating into wood pores as visible after SEM observation, which reduced coating adhesion on the substrate. CNC improved fungal resistance as seen by a reduced mass loss and FTIR spectroscopy thanks to crosslinks formation, which reduced water sorption as well. Color change was not significant, and, on the other hand, glossiness was reduced but resulted as more homogeneous than control. CNC addition gave good results also in blue stain protection. CNC improved scratch resistance, but no visible change to impact was registered. CNC has promising results in coatings depending on wood and fungal species and presence of further commercial additives (biocides).

Starch-Based Bioplastic Reinforced by Cellulose Nanocrystal Isolated from Water Hyacinth

This study aims to determine the effect of the addition of cellulose nanocrystals (CNC) with different concentrations (0,2,4,6,8,10%) isolated from water hyacinth on tensile strength, elongation, and biodegradability of corn starch bioplastics. CNC isolation was conducted, including alkalization, bleaching, acid hydrolysis, and sonication. After the isolation process, CNC was characterized based on functional group, crystallinity, and morphology surface. Then, the production of starch bioplastic using solution casting was carried out with the addition of CNC. The results showed chemical treatments affected the functional group, increasing the crystallinity index, and removing the fibril structure in water hyacinth fibers. Likewise, the addition of CNC to starch bioplastic fluctuated the tensile strength and elongation. In the biodegradability test, the physical appearance of the bioplastic completely changed. Then, the optimum mass reduction occurred in the 6% CNC on the 10th day.

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.

Date Palm Cellulose Nanocrystals (CNCs)/Polyamide Composites: Tailoring Morphological, Mechanical, and Thermal Properties

In the present study, polyamide (PA) was successfully reinforced with cellulose nanocrystal (CNC) prepared from date palm leaves using two different techniques, electrospinning and the solution casting method, and a comparative study of these two systems was performed. The morphological, thermal, wetting, and mechanical properties of the nanocomposites were analyzed for CNC content between 0 and 5 wt%. Morphological analyses showed different roughness in the fractured surface of neat PA and its nanocomposites after the addition of CNC. The modified composite is found to have a smooth surface without cracks and showed increased roughness with greater hydrophilicity and thermal stability. The nano-indentation results showed that the highest hardness was obtained at 5% CNC loading for the solution cast composite samples, which could be related to the relatively good CNC dispersion with good filler matrix bonding as evidenced by the morphological characterization. We also observed that the electrospinning technique produced nanocomposites of better thermo-physical properties than the solution cast method. The results point to the prospect of the development of nanocomposite films using date-palm-leaf-derived CNC incorporated in PA for high-performance and advanced material applications such as membranes.

Preparation of A Dynamically Vulcanized Nanocomposite Thermoplastic Based on PLA/NR and Cellulose Nanocrystal (CNC)

Dynamically vulcanized nanocomposite thermoplastic based on poly (lactic acid) (PLA)/natural rubber (NR) is prepared through a dynamic curing process. The cross-linked NR phase exhibits a continuous network structure embedded in the PLA phase, which differs from the conventional plastic/rubber system with an "island-sea" morphology in which vulcanized rubber particles are dispersed in the plastic matrix. Its favorable internal interfacial compatibility was confirmed by SEM analysis. Also, CNC has been used as a sustainable additive to improve the mechanical properties of PLA/NR thermoplastic vulcanizate (TPV). To achieve homogeneous dispersion of CNC, the melt mixing method was used. The mechanical properties were considerably enhanced by CNC addition, which increased from 14% of the unfilled TPV to 70% of the sample with CNC (1.5 phr relative to PLA). The "green" raw materials and high mechanical properties of PLA/NR/CNC prepared from the dynamic curing process are expected to open up a wide range of potential applications in the fields of smart medicine.

Preparation of cellulose nanocrystal (CNCs) reinforced polylactic acid (PLA) bionanocomposites filaments using biobased additives for 3D printing applications.

This work presents the experimental steps taken towards the preparation of 3D printable bionanocomposites using polylactic acid (PLA) biopolymer containing 0.1, 0.5 and 1 wt% CNCs. Optimized amounts of bio-based additives were added to improve the processability and flexibility of the bionanocomposites. The 3D printable bionanocomposite filaments were drawn using a single screw extruder. The bionanocomposites filament was used to 3D print prototypes and test specimens for dynamic mechanical analysis (DMA). Characterization of the CNCs and bionanocomposites was performed using Fourier Transform Infrared Spectroscopy (FTIR) analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The nucleating effect of CNCs enhanced the crystallization behaviour of bionanocomposites by 5%, 15% and 11%, for the different CNCs loadings. The TGA analysis revealed a ∼20 °C improvement in the thermal stability of the bionanocomposites. Meanwhile, the tensile analysis showed a ≥48% increase in the tensile strength of the bionanocomposites filaments which was attributed to the reinforcing effects of CNC. The addition of CNCs significantly increased the melt viscosity, storage and loss modulus of PLA. In summary, the bionanocomposite filaments produced in this study exhibited excellent processibility and superior mechanical and thermal properties.

Improving the decorative performance of UV-curable coatings with iridescent cellulose nanocrystal film.

Cellulose nanocrystals (CNC) possess remarkable mechanical properties, a high aspect ratio, a large specific surface area, and a unique nanostructure, making them a popular choice in various fields. In this study, a CNC suspension was prepared through acid hydrolysis, and subsequently, a film exhibiting iridescence and chiral nematic structure was formed on the cured UV-WA surface via evaporation-induced self-assembly. The mean diameter and length of CNC were determined to be 25.1-33.3 nm and 281.3-404.2 nm, respectively, through transmission electron microscope analysis. The experimental results revealed that the color of the film significantly changes with variations in the CNC suspension concentration. Notably, the formation of the iridescent film is dependent on the concentration of CNC, with concentrations between 1.2% and 2.9% being optimal, and the aspect ratio of the CNC nanoparticles being around 11.3. X-ray diffraction analysis confirmed that the CNC nanoparticles possess the same crystal structure as microcrystalline cellulose (cellulose I). Fourier transform infrared spectroscopy revealed that the C[double bond, length as m-dash]C bond present in the liquid UV-curable coating disappeared upon UV irradiation. The performance of the CNC iridescent film, with varying thickness, was evaluated using UV-vis spectroscopy. The thermogravimetric analysis results indicate that the addition of CNC enhances the membrane's thermal stability and heat resistance. The results indicate that as the thickness of the CNC iridescent film increases, the corresponding UV-vis spectra display a redshift. The UV-WA/CNC shows potential in the field of decoration and establishing a straightforward, cost-effective, and efficient method for producing photonic materials with structural colors.

Preparation and properties of cellulose nanocrystals-reinforced Poly (lactic acid) composite filaments for 3D printing applications

In this work, the composite filaments containing different cellulose nanocrystals (CNCs) were successfully fabricated by using a single screw extruder and used to 3D print. The influence of CNCs contents (0, 0.75, 1, and 2 wt%) on the properties of the filaments and 3D printed samples were evaluated. The properties of the filaments and 3D printed samples were characterized by using SEM, FT-IR, XRD, DSC, TGA, and tensile tests. Results revealed that no chemical changes occurred in the presence of CNCs but improved crystallinity was found. The presence of 2 wt% CNCs slightly improved the thermal stability of the neat PLA filament and 3D printed sample. The tensile strength of the neat PLA filament was enhanced by 18.2% by adding up to 1 wt% CNCs but reduced at 2 wt% CNCs content. For the 3D printed samples, the tensile strength of the neat PLA was improved by 11% with the introduction of 0.75 wt% CNCs and decreased for further CNC addition. In addition, compared with the 3D printed samples, the filaments exhibited a higher tensile strength for all CNCs contents. Furthermore, the water absorption of the composite filaments was increased with increasing the CNCs contents. On the other hand, the 3D printed samples containing CNCs showed a lower water absorption than the neat PLA.

The Influence of the Surface Chemistry of Cellulose Nanocrystals on Ethyl Lauroyl Arginate Foam Stability.

Guanidine-based surfactant ethyl lauroyl arginate (LAE) and cellulose nanocrystals (CNCs) form complexes of enhanced surface activity when compared to pure surfactants. The LAE-CNC mixtures show enhanced foaming properties. The dynamic thin-film balance technique (DTFB) was used to study the morphology, drainage and rupture of LAE-CNC thin liquid films under constant driving pressure. A total of three concentrations of surfactant and the corresponding mixtures of LAE with sulfated (sCNC) and carboxylated (cCNC) cellulose nanocrystals were studied. The sCNC and cCNC suspension with LAE formed thin films, with stability increasing with surfactant concentration and with complex rheological properties. In the presence of LAE, the aggregation of CNC was observed. While the sCNC aggregates were preferentially present in the film volume with a small fraction at the surface, the cCNC aggregates, due to their higher hydrophobicity, were preferentially located at film interfaces, forming compact layers. The presence of both types of aggregates decreased the stability of the thin liquid film compared to the one for the LAE solution with the same concentration. The addition of CNC to LAE was critical for foam formation, and foam stability was in qualitative agreement with the thin films' lifetimes. The foam volume increased with the LAE concentration. However, there was an optimum surfactant concentration to achieve stable foam. In particular, the very resistant foam was obtained with cCNC suspensions that formed the interfaces with a complex structure and rheology. On the other hand, at high LAE concentrations, the aggregates of CNC may exhibit antifoaming properties.

CNC Synthesis from Cellulose Macromolecule and Fabrication of PVA/TiO2/CNC Bio-Nanocomposite Thin Film for Biomedical Applications

PolyVinyl Alcohol (PVA) based films with varying concentrations of Cellulose Nano Crystals (CNC) and Titanium dioxide (TiO2) have been prepared and characterised in this study to determine their applications in the biomedical field. Biophysical, microscopic and mechanical property characterization of the films - PVA/CNC/T0.5, PVA/CNC/T1.0 and PVA/CNC/T1.5 were performed. The CNC were extracted from pea peel waste fibres (PPWF) which are rich in cellulose macromolecule (Mol Wt > 5000 da) by adopting acid hydrolysis method. Through Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis, uniform distribution and successful incorporation of CNC and TiO2 in the films have been confirmed. From the X-ray diffraction pattern of the films, it could be noted that the crystallinity increased in the films with the addition of CNC and rutile TiO2 in the PVA. The tensile strength of the films also greatly improved with the CNC reinforcement and increase in TiO2 content in the films. Overall, the results of this study suggest that the PVA/CNC/ TiO2 films have the potential to find their application in biomedical devices, especially to be used as a footprint of an ultrasound transducer.

A study on thermal resistance evaluation of carbon nanotube buckypaper with cellulose material for thermal interface material

Multi-walled carbon nanotubes (MWCNTs), which has been studied as a heat conduction material, has excellent thermal properties, with thermal conductivity value of 3000 W/m·K. This study aims to reduce the thermal resistance of MWCNTs–buckypaper (BP) as a thermal interface material (TIM). Three methods are used in this experiment: ultrasonication, oxidation, and the addition of cellulose nanocrystal (CNC). The oxidation process is to remove impurities, which when prepared as a suspension, disturb the particle dispersion, and reveal a tendency to agglomerate. Therefore, a strong acid treatment removes impurities, and improves the dispersibility of nanofluids. The third method, the addition of CNC, which has been in the limelight recently, can affect structural stability, is eco-friendly, and is used for composite material synthesis with high tensile strength. These preeminent effects of CNC help improve the thermal resistance of CNC/treated CNT (C–tCNTs) mixed buckypaper. The thermal performances of TIMs used an ASTM D5470 standard tester, and various ratios of BP were tested using thermal resistance test. BP manufactured by adding MWCNTs and CNC had a resistance value of 0.776. This provided a 33.1 % decrease, compared to the oxidized MWCNTs BP. As a result, it was confirmed that CNC–CNTs BP has the possibility of being applied as TIM. • Cellulose nanocrystals, an eco-friendly material, are applied to carbon nanotubes. • It is made of paper-type buckypaper for use as a thermal interface material. • ASTM D5470 standard instrument is used for thermal resistance comparison. • It achieves maximum heat transfer performance at the optimum ratio.

Green-in-green biohybrids as transient biotriboelectric nanogenerators

Green self-powered devices based on biodegradable materials have attracted widespread attention. Here, we propose the construction of the transient biotriboelectric nanogenerator (TENG) using green-in-green bionanocompoites. The green-in-green nanocomposites, cellulose nanocrystal (CNC)/polyhydroxybutyrate (PHB), are prepared with a high-pressure molding method. The CNC promotes the degradation and enhances the dielectric constant of CNC/PHB. It further allows for the significant improvement of the triboelectric output of CNC/PHB-based TENG. The voltage output and current output of CNC/PHB-based TENG are 5.7 and 12.5 times higher than those of pristine PHB-based TENG, respectively. Also, the bio-TENG exhibits admirable signal stability in over 20000 cycles. Despite the high hardness of CNC/PHB, a soft but simple-structured arch sensor is successfully assembled using CNC/PHB-based TENG. It can attain the precise real-time monitoring of various human motions. This study may provide new insights into the design/fabrication of green functional materials, and initiate the next wave of innovations in eco-friendly self-powered devices.

Crosslinked poly (vinyl alcohol) composite reinforced with tunicate, wood, and hybrid cellulose nanocrystals: Comparative physicochemical, thermal, and mechanical properties

The development of sustainable and biodegradable composites has gained increasing attention in recent years. Effective interaction and adhesion between polymers and fillers are crucial. In this study, the effect of different aspect ratios of cellulose nanocrystals (CNCs) and their hybrid within a crosslinked poly (vinyl alcohol) (PVA) nanocomposite has been investigated to develop biodegradable materials. The physicochemical, thermal, and mechanical properties of the specimens have been studied. SEM images indicate that the addition of CNC reduced the porosity of the films. The XPS results confirmed the significant formation of covalent bonds for all composites except those reinforced with wood-CNC, which showed a lower amount of crosslinking and CC formation. EDS maps reveals that the dispersity of the CNCs could be different depending on the aspect ratio of the CNCs. Results from the solubility in water (SW) tests indicated that the use of hybrid-CNC in a crosslinked system decreased the SW significantly. The crosslinking and addition of CNC to the PVA composite led to improved mechanical properties. Elongation at break (EB) decreased significantly for the crosslinked hybrid-CNC nanocomposite. Overall, the results of this study indicate that the aspect ratio of CNCs as fillers in nanocomposites may contribute to their physicochemical, mechanical, and thermal properties for the development of biodegradable materials.

Effect of Cellulose Material-Based Additives on Dispersibility of Carbon Nanotubes

In nanoscience, nanotechnology is applied to various technologies, and research is actively being conducted. As the application of multi-walled carbon nanotubes (MWCNTs) in various fields increases, efforts have been made to develop dispersion and functionalization technologies. In order to effectively use MWCNT nanofluids, it is most important to solve the problem of dispersion. In this study, MWCNTs were improved in dispersibility and functionalized through various chemical and mechanical treatments. In addition, MWCNTs aggregation was alleviated by using cellulose nanocrystal (CNC) as a dispersant. The processing results of MWCNTs and CNC were analyzed through transmission electron microscopy (TEM) and the dispersion was characterized by UV–Vis spectroscopy. The addition of CNC to MWCNTs has been confirmed to have high dispersibility and improved stability compared to untreated MWCNTs, and this effect affects the quality of the machine.

Thermo-sensitive composite microspheres incorporating cellulose nanocrystals for regulated drug release kinetics

Thermo-sensitive composite microspheres (TPCP) were developed to achieve the on-demand release of drugs. The TPCP microspheres were synthesized using Oil-in-Water (O/W) emulsion evaporation technique and then impregnated with thermo-sensitive polyethylene glycol (PEG). The addition of cellulose nanocrystals (CNCs) significantly enhance thermal stability, crystallization ability, and surface hydrophilicity of TPCP microspheres due to heterogeneous nucleation effect and hydrogen bonding interaction, resulting in stable microsphere structure. The thermal degradation temperature (Tmax) increased by 13.8 °C, and the crystallinity improved by 20.9 % for 10 % TPCP. The thermo-sensitive composite microspheres showed the regulated cumulative release according to in vitro human physiological temperature changes. Besides, four release kinetics and possible release mechanism of TPCP microspheres were provided. Such thermo-responsive composite microspheres with control microsphere sizes and high encapsulation rate may have the potential to the development of on-demand and advanced controlled-release delivery systems.

Preparation of garlic stem cellulose nanocrystal/leaf extract/chitosan film for black garlic preservation by electrostatic spraying

In this study, a novel active chitosan (CH) packaging film that incorporates garlic leaf extract (GL) and stem cellulose nanocrystals (CNC) was prepared. The addition of CNC to the CH film increased its tensile strength, hydrophilicity, thermal stability, and water/oxygen barrier and decreased its water contact angle and weight-loss rate, while the addition of GL greatly enhanced its antioxidant and antibacterial activities. SEM and AFM analyses showed that the CNC agglomerates and deposits in the lower layer and the surface roughness of the film was the highest at 1.2 % concentration. The optimal composition of the film was determined to be 0.8 % CNC and 4 % GL by the fuzzy mathematics evaluation method. Then, black garlic was preserved with the optimized coating by electrostatic spraying and was found to slow water loss and migration, while its excellent antioxidant activities decreased the degree of browning during 90 d of storage.

Fabrication of Poly(Vinyl) Alcohol-Cellulose Nanocrystal Hybrid Aerogel

In this paper, a series of polyvinyl alcohol (PVA) aerogels hybrid with cellulose nanocrystal (CNC) was successfully prepared using freeze-drying process. The influence of different fractions of CNC and crosslinking agent; glutaraldehyde (GA) on the mechanical of PVA/CNC hybrid aerogels property was evaluated by means of compressive strength. Results show that the mechanical property of hybrid aerogels has been improved with the addition of CNC and GA. Variation in the CNC and GA content also led to differences in the porous structure morphologies. Nevertheless, higher content of GA caused adverse effect to the strength of hybrid aerogel which associated to the excessive crosslinking and smaller number of pores formation as evident from scanning electron microscopy (SEM) analysis.

Production of cellulose nanocrystals extracted from Pennisetum purpureum fibers and its application as a lubricating additive in engine oil

In the present work, cellulose nanocrystals (CNCs) were successfully produced from the Pennisetum purpureum (PP) fibers through ammonium persulfate (APS) oxidation. The effect of oxidation temperatures (60, 70, and 80 °C) on the properties of CNCs was characterized. In addition, the influence of CNCs addition (0, 0.05, 0.1, and 0.2 wt%) on the lubrication properties of the base oil SAE 40 lubricant was also investigated. The characteristics of the CNCs were determined by using FT-IR, XRD, TEM, and TGA. The lubrication properties were evaluated using kinematic viscosity and viscosity index measurements. The optimal oxidation temperature was found at 60 °C which resulted in the needle-shaped CNCs particles with high crystallinity (66.56%), an average diameter (15 nm), and an average length (79 nm). The resulting CNCs exhibited higher thermal stability than the PP fibers. Both kinematic viscosity and viscosity index did not significantly change by increasing the CNCs contents. However, a slightly higher viscosity index was exhibited for 0.2 wt% CNCs compared to that of neat base oil SAE 40. The CNCs obtained had high potential as a reinforcing agent of nanocomposites and also as a bio-lubricating additive in engine oil.