Enhancing Chitosan Films for Egg Packaging Using Cellulose Nanocrystals and Sodium Montmorillonite Nanoparticles.

The effect of two types of nanocellulose on the mechanical properties of chitosan (CH) film was examined in terms of elongation, tensile strength, and dynamic-mechanical properties such as tan δ and storage modulus. Chitosan films were reinforced by cellulose nanocrystal (CNC) and cellulose nanofiber (CNF) with different ratios. CH/CNC and CH/CNF nanocomposite films containing 0–7 wt.% nanofibers were produced by solution casting. A comparison between CNC and CNF was made based on their nanostructures and interfacial bonding with the CH matrix. For both CNC and CNF, reinforcing effects in nanocomposite polymer films were presented. The results demonstrated that nanocomposite films can increase mechanical properties; 7 wt.% CNF and CNC had the most increasing effect on the mechanical properties, raising the tensile strength of the chitosan film by 104% and 52%, respectively. Moreover, the values of CH/CNC and CH/CNF films showed higher storage modulus compared to the pure chitosan film. CNF shows higher modulus and strength compared with CNC at the same amount of fiber because of CNFs’ percolation networks and their larger aspect ratio. Morphological studies revealed the dispersion of CNC and CNF is in the contiguous matrix of chitosan with a homogeneous distribution without agglomeration. The results also illustrated that CNC and CNF can improve the water resistance of chitosan films. The mechanical properties of composite films were acceptable to use as artificial skin and wound dressings.

Traditional food packaging systems help reduce food wastage, but they also produce environmental impacts when not properly disposed of. Bio-based polymers are a promising solution to overcome these impacts, but they have poor barrier and mechanical properties. This work evaluates two strategies to improve these properties in pectin films: the incorporation of cellulose nanocrystals (CNC) or sodium montmorillonite (MMT) nanoparticles, and an additional layer of chitosan (i.e., a bilayer film). The bionanocomposites and bilayer films were characterized in terms of optical, morphological, hygroscopic, mechanical and barrier properties. The inclusion of the nanofillers in the polymer reduced the water vapor permeability and the hydrophilicity of the films without compromising their visual properties (i.e., their transparency). However, the nanoparticles did not substantially improve the mechanical properties of the bionanocomposites. Regarding the bilayer films, FTIR and contact angle studies revealed no surface and/or chemical modifications, confirming only physical coating/lamination between the two polymers. These bilayer films exhibited a dense homogenous structure, with intermediate optical and hygroscopic properties. An additional layer of chitosan did not improve the mechanical, water vapor and oxygen barrier properties of the pectin films. However, this additional layer made the material more hydrophobic, which may play an important role in the application of pectin as a food packaging material.

This pilot study aimed to fill the knowledge gap on incorporating cellulose nanocrystals (CNC) in concrete pavements in real-world construction settings. The constructability of CNC concrete was evaluated, and the fresh and hardened properties were fully characterised. A series of concrete slabs were placed using ordinary portland cement concrete (OPC mix), portland limestone cement concrete (PLC mix), and PLC-concrete with CNC at a dosage of 0.10% wt. of cementitious materials (CNC mix). CNC and PLC mix showed no significant differences in consistency, workability, and other fresh properties. The addition of CNC did not show significant changes in cumulative heat over PLC. CNC did not lead to notable changes in compressive and flexural strength, modulus of elasticity, coefficient of thermal expansion (CTE), and electrical resistivity. However, the CNC mix had a notably 9% lower drying shrinkage strain at seven months than the PLC mix. The PLC mix exhibited the lowest water absorption rate, while CNC did not induce significant changes. Overall, this study highlights the constructability of concrete slabs with CNC, with notable contributions of CNC to reducing long-term drying shrinkage.

Interpenetrating and semi-interpenetrating network superabsorbent hydrogels based on sodium alginate and cellulose nanocrystals: A biodegradable and high-performance solution for adult incontinence pads

Biological lubricants are essential for the effective functioning of biomedical systems that involve relative motion. Hyaluronic acid (HA) is often used for its excellent lubrication properties; however, its long-term effectiveness is compromised by its tendency to accelerate metal corrosion. Incorporating cellulose nanocrystals (CNCs) into HA offers a promising solution due to CNCs' corrosion-inhibition properties, tunable rheological behavior, and tribological properties. This study examines the impact of varying HA and CNC concentrations on friction, wear, and corrosion in HA/CNC suspensions. Optimal performance was achieved with 2wt% CNC in 1mg/mL HA, corresponding to the onset of gelation. Below this CNC concentration, lubrication improves through the formation of a protective film and the mitigation of corrosion. Increasing CNC beyond 2wt% yields minimal additional benefit. HA concentration also plays a key role: at low HA levels, corrosion predominates, leading to increased friction and wear. In contrast, HA levels above 1mg/mL in 2wt% CNC suspensions enhance lubricant film formation due to improved rheology, resulting in reduced wear, coefficient of friction, and corrosion. These results underscore the importance of optimizing HA and CNC concentrations to maximize their synergistic effects in advanced bio-tribological lubrication applications.

Surface-initiated atom transfer radical polymerization was used to graft hydrophobic poly(butyl acrylate) from cellulose nanocrystals (CNCs) resulting in compatibilized CNCs that were successfully incorporated inside the core of polymer latex particles. CNCs are anisotropic nanoparticles derived from renewable resources and have potential as reinforcing agents in nanocomposites. However, challenges due to the incompatibility between cellulose and hydrophobic polymers and processing difficulties, such as aggregation, have limited the performance of CNC nanocomposites produced to date. Here, CNCs were incorporated into the miniemulsion polymerization of methyl methacrylate by adding polymer-grafted CNCs to the monomer phase. A poly(methyl methacrylate)-CNC nanocomposite latex was subsequently produced in situ, whereby polymer-grafted CNCs (with optimized graft length) were located inside the latex particles, as shown by transmission electron microscopy. This work provides a method for controlling the location of CNCs in latex-based nanocomposites and may extend the use of CNCs in commercial adhesives and coatings.

The objective of this work is to improve the mechanical properties of polylactic acid (PLA) by incorporating cellulose nanocrystals (CNC) previously obtained from a cellulose pulp extracted from olive tree pruning (OTP) waste. Composites were manufactured by melt processing and injection moulding to evaluate the effect of the introduction of CNC with conventional manufacturing methods. This OTP-cellulose pulp was subjected to a further purification process by bleaching, thus bringing the cellulose content up to 86.1%wt. This highly purified cellulose was hydrolysed with sulfuric acid to obtain CNCs with an average length of 267 nm and a degradation temperature of 300 °C. The CNCs obtained were used in different percentages (1, 3, and 5%wt.) as reinforcement in the manufacture of PLA-based composites. The effect of incorporating CNC into PLA matrix on the mechanical, water absorption, thermal, structural, and morphological properties was studied. Maximum tensile stress and Young’s modulus improved by 87 and 58%, respectively, by incorporating 3 and 5%wt. CNC. Charpy impact strength increased by 21% with 3%wt. These results were attributed to the good dispersion of CNCs in the matrix, which was corroborated by SEM images. Crystallinity index, glass transition, and melting temperatures were maintained.

The aim of this study was to produce innovative edible films and coatings with various combinations of materials, in order to achieve the best possible resulting properties. More specifically, the effect of cellulose nanocrystals (CNC) or beta-cyclodextrin (CD) addition to chitosan (CH) films and the development of composite CH–CNC–CD films were investigated. According to the results, most properties of both CH–CNC and CH–CD edible films were improved. The viscosity of the solutions was decreased up to 50% while the surface tension was minimally changed even at high levels of CNC or CD addition. Furthermore, oxygen and water vapor permeability of the CH–CNC and the CH–CD edible films was decreased, whereas transparency and heterogeneity were increased. On the other hand, the study of the composite CH–CNC–CD films, showed that CNC improved viscosity, supporting thus the coating procedure. Moreover, CNC led to more stable structures with enhanced mechanical properties. Finally, CD mostly contributed to the improvement of the optical properties (lighter color and increased transparency).

Extraction of cellulose nanocrystals from areca waste and its application in eco-friendly biocomposite film

The potential of developing nanocomposite‐based biofilms by incorporating cellulose nanocrystals (CNC) into chitosan (Chi) matrices has yet to be fully explored. This study specifically examined how the incorporation of CNC influences the surface hydrophobicity and ultraviolet–visible (UV–vis) light barrier properties of Chi‐based biofilms, with the aim of enhancing their suitability for active food packaging applications. Film‐forming solutions were prepared using 0.8% chitosan blended with CNC at varying concentrations (0%, 0.1%, 0.5%, and 1%). The morphology of CNC was analyzed using atomic force microscopy (AFM). Results showed that CNC addition enhanced both UV and visible light barrier properties, as well as the hydrophobicity of the films. Scanning electron microscopy (SEM) was used to examine the surface and internal microstructure of the films. Overall, the study indicates that the developed CNC–Chi nanocomposite films possess promising potential for application as environmentally friendly active packaging materials.

Increasing environmental awareness has promoted development of ecofriendly materials incorporating renewable raw materials and using green synthesis routes such as waterborne dispersion, avoiding employment of organic solvents and thus reducing generation of volatile organic compounds. In this regard, waterborne polyurethanes (WBPU) present an opportunity to tailor material properties while meeting application requirements and avoiding use of organic solvents. In addition, WBPU dispersions offer the possibility to incorporate hydrophilic water-dispersible reinforcement materials, such as cellulose nanocrystals (CNC), which represent a suitable candidate for preparation of nanocomposites due to their renewability, availability, and unique properties resulting from their nanoscale dimension. Therefore, in this work, different WBPU having small particle size with narrow distribution were synthesized at various isocyanate/hydroxyl (NCO/OH) group ratios, and CNC were isolated for preparation of nanocomposites with 1, 3, or 5 wt% CNC by solvent casting. It was observed that, just by varying the NCO/OH ratio, the polyurethane microstructure was altered, resulting in different ordered structures. At low NCO/OH ratio, soft ordered domains were observed, whereas at higher NCO/OH ratio, hard ordered domains were obtained. These different microstructures of the matrix induced different behaviors of the CNC reinforcement, acting either as crystal growth inhibitor or nucleating agent, thereby modulating the properties of the final material in different ways.

Cellulose nanocrystal (CNC)-reinforced bio-composite films containing glycerol were produced using the solution casting technique. The influences of the addition of CNC (2, 4, and 8 wt%) and glycerol (10, 20, and 30 wt%) on the properties of the bio-composite films were studied in the present work. The resulting films were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetry analysis (TGA), and according to their tensile, water absorption, and light transmission behavior. The introduction of 4 wt% CNC into the chitosan film did not affect the thermal stability, but the presence of 20 wt% glycerol reduced the thermal stability. The addition of 4 wt% CNC to the chitosan film increased its tensile strength, tensile modulus, and elongation at break by 206%, 138%, and 277%, respectively. However, adding more than 8 wt% CNC resulted in a drastic reduction in the strength and ductility of the chitosan film. The highest strength and stiffness of the chitosan bio-composite film were attained with 4 wt% CNC and 20 wt% glycerol. The water absorption and light transmission of the chitosan film were reduced dramatically by the presence of both CNC and glycerol.

Cellulose nanocrystals (CNCs) were acetylated to the various parametrised degrees of substitution (DS), determined through attenuated total reflection Fourier transform infrared spectroscopy (ATR–FTIR) and incorporated into alginate (ALG) and chitosan (CH) film-forming solutions. An investigation of morphology with scanning electron microscopy (SEM) revealed increased chemical compatibility with the CH matrix after acetylation, producing a smooth surface layer, while ALG mixed better with pristine CNCs. The ATR–FTIR analysis of films demonstrated inter-diffusional structural changes upon the integration of pristine/modified CNCs. Films were evaluated in terms of water contact angle (WCA), which decreased upon CNC addition in either of the biocomposite types. The H2O barrier assessed through applicative vapour transmission (WVT) rate increased with the CNC esterification in CH, but was not influenced in ALG. To evaluate the relationship between environmental humidity and mechanical properties, conditioning was applied for 48 h under controlled relative humidity (33%, 54% and 75%) prior to the evaluation of the mechanical properties and moisture content. It was observed that tensile strength was highest upon specimens being dry (25 ± 3 MPa for ALG, reinforced with neat CNCs, or 16 ± 2 MPa in the CH with CNCs, reacting to the highest DS), lowering with dewing, and the elongation at break exhibited the opposite. It is worth noting that the modification of CNCs improved the best base benchmark stress–strain performance. Lastly, (thermal) stability was assessed by means of the thermogravimetric analysis (TGA) technique, suggesting a slight improvement.

A biodegradable packaging paper with excellent grease resistance was produced using cellulose nanocrystals and sodium alginate. This study aims to reduce the porosity of paper by filling the pores with cellulose nanocrystals and using sodium alginate as a binder. Different types of papers, including filter paper, copy paper, and supercalendered paper, were used. Pure cellulose nanocrystals and cellulose nanocrystals/sodium alginate solutions at different concentrations and ratios (2:8, 5:5, and 9:1 by weight ratio) were applied to papers by coating and impregnation techniques. The resulting papers were then characterized with atomic force microscopy and scanning electron microscopy for the surface morphology. The grease barrier and the mechanical property were investigated in accordance with TAPPI standards. The results demonstrated that the copy paper coated with 2:8 of cellulose nanocrystals/sodium alginate showed excellent grease barrier properties. Within 48 h of the test period for grease to penetrate the coated paper, almost 100% of the grease barrier was achieved when the coating weight was set at 4 g/m2. The roughness of the paper surface significantly decreased, thereby resisting the penetration of oil from one side to another. Moreover, the mechanical property of both cellulose nanocrystals- and cellulose nanocrystals/sodium alginate-coated papers was improved due to the addition of cellulose nanocrystals as a reinforced filler.

3D printed polycaprolactone scaffold incorporated with tragacanth gum/bioactive glass and cellulose nanocrystals for bone tissue engineering.