Innovative process for obtaining modified nanocellulose from soybean straw

Emerging nanocellulose from agricultural waste: Recent advances in preparation and applications in biobased food packaging

With the increasing emphasis on sustainability and eco-friendliness, a novel biodegradable packaging materials has received unprecedented attention. Nanocellulose, owing to its high crystallinity, degradability, minimal toxicity, and outstanding biocompatibility, has gained considerable interest in the field of sustainable packaging. This review provided a comprehensive perspective about the recent advances and future development of cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs). We first introduced the utilization of agricultural waste for nanocellulose production, such as straw, bagasse, fruit byproducts, and shells. Next, we discussed the preparation process of nanocellulose from various agricultural wastes and expounded the advantages and shortcomings of different methods. Subsequently, this review offered an in-depth investigation on the application of nanocellulose in food packaging, especially the function and packaged form of nanocellulose on food preservation. Finally, the safety evaluation of nanocellulose in food packaging is conducted to enlighten and promote the perfection of relevant regulatory documents. In short, this review provided valuable insights for potential research on the biobased materials utilized in future food packaging.

Biodegradable starch foams reinforced by food-chain side streams

Biodegradable starch foam trays offer an eco-friendly substitute for petroleum-based single-use packaging, notably polystyrene foams. However, they lack flexibility, tensile strength, and water-sensitivity, addressable through lignocellulosic reinforcement. This study aimed to develop biodegradable starch foam trays filled with different food-chain side streams for sustainable alternative packaging. Corncob, soybean straw, cassava peel, araucaria seed hull, yerba mate stalks and yerba mate leaves petiole were collected, dried and ground to <250 μm. The trays were filled with 13 % (w/w) of each food-chain side streams and produced by hot molding. The trays morphology, moisture, water activity (aw), thickness, bulk density, tensile strength, elongation at break, Young's modulus, bending strength, maximum deflection, and sorption isotherms were investigated. Reinforcements slightly increased the foams bulk density, reduced the tensile strength and maximum deflection and while bending strength increased from 0.20 MPa to 1.17-1.80 MPa. The elasticity modulus decreased by adding any filling, that resulted in ductility improvement; however, these packaging have moisture-sensitive material especially for aw higher than 0.52, which drives the use recommendation for dry products storage or shipping/transport. The biodegradable starch foam trays filled with side streams were successfully produced and offer excellent alternative to petroleum-based packaging low-density material with bending strength improved.

Current progress in functionalization of cellulose nanofibers (CNFs) for active food packaging

There is a growing interest in utilizing renewable biomass resources to manufacture environmentally friendly active food packaging, against the petroleum-based polymers. Cellulose nanofibers (CNFs) have received significant attention recently due to their sustainability, biodegradability, and widely available sources. CNFs are generally obtained through chemical or physical treatment, wherein the original surface chemistry and interfacial interactions can be changed if the functionalization process is applied. This review focuses on promising and sustainable methods of functionalization to broaden the potential uses of CNFs in active food packaging. Novel aspects, including functionalization before, during and after cellulose isolation, and functionalization during and after material processing are addressed. The CNF-involved structural construction including films, membranes, hydrogels, aerogels, foams, and microcapsules, is illustrated, which enables to explore the correlations between structure and performance in active food packaging. Additionally, the enhancement of CNFs on multiple properties of active food packaging are discussed, in which the interaction between active packaging systems and encapsulated food or the internal environment are highlighted. This review emphasizes novel approaches and emerging trends that have the potential to revolutionize the field, paving the way for advancements in the properties and applications of CNF-involved active food packaging.

Comparison of Emulsion Stabilizers: Application for the Enhancement of the Bioactivity of Lemongrass Essential Oil

Recent focus on cellulose nanomaterials, particularly biodegradable and biocompatible cellulose nanocrystals (CNCs), has prompted their use as emulsion stabilizers. CNCs, when combined with salt, demonstrate enhanced emulsion stabilization. This study explored three emulsion stabilizers: Tween 80, soybean CNCs with salt (salted CNCs), and a combination of salted CNCs with Tween 80. Soybean CNCs, derived from soybean stover, were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Antifungal testing against Aspergillus flavus revealed increased bioactivity in all lemongrass essential oil (EO)-loaded emulsions compared to pure essential oil. In addition, all three emulsions exhibited a slight reduction in antifungal activity after 30 days of room temperature storage. The release experiment revealed that the EO-loaded nanoemulsion exhibited a slow-release profile. The nanoemulsion stabilized by salted CNCs and Tween 80 exhibited significantly lower release rates when compared to the nanoemulsion stabilized solely by Tween 80, attributed to the gel network formed by salted CNCs. The findings of this study highlight the efficacy of cellulose nanocrystals procured from soybean byproducts in conjunction with synthetic surfactants to create nanoencapsulated essential oils, resulting in improved antimicrobial efficacy and the achievement of sustained release properties.

Synergistic Stabilization of Nanoemulsion Using Nonionic Surfactants and Salt-Sensitive Cellulose Nanocrystals

Soybean stover is a lignocellulose biomass that is rich in cellulose. In the present study, soybean cellulose nanocrystals (CNCs) were prepared from soybean stover by alkaline treatment, bleaching treatment, acid hydrolysis, dialysis and ultrasonication. The as-prepared soybean CNC was characterized by transmission electron microscopy (TEM), zetasizer and rheometer. The effects of NaCl on the particle size, zeta potential, and viscosity of soybean CNC was studied. Soybean CNC was explored as an emulsion stabilizer for lemongrass-essential-oil-loaded emulsions. Soybean CNCs could stabilize the oil-in-water emulsion against coalescence but not flocculation. The addition of NaCl reduced the creaming index and enhanced the encapsulation efficiency and freeze-thaw stability of the CNC-stabilized emulsion. Salted CNC (i.e., CNC in the presence of NaCl) enhanced the thermodynamic stability (i.e., heating-cooling and freeze-thaw stability) of Tween 80 stabilized emulsion, while unsalted CNC did not. Synergistic effects existed between Tween 80 and salted CNC in stabilizing oil-in-water emulsions. The nanoemulsion stabilized with Tween 80 and salted CNC had a mean particle size of ~70 nm, and it was stable against all thermodynamic stability tests. This is the first study to report the synergistic interaction between salted CNC and small molecular weight surfactants (e.g., Tween 80) to improve the thermodynamic stability of nanoemulsion.

Graphene composite paper synergized with micro/nanocellulose-fiber and silk fibroin for flexible strain sensor

The fabrication of uniform and strong graphene-based conductive paper is challenging due to easy aggregation and poor film formability of graphene. Herein, on the basis of good dispersing effect of nanocellulose, high content graphene (50 wt%) composite paper with micro/nanocellulose fibers and silk fibroin (SF) was manufactured via simple casting method. The synergistic effects of cellulose microfibers (CMFs), cellulose nanofibers (CNFs) and SF result in the paper with ideal combination of flexibility, electrical conductivity and mechanical strength, where CNFs, CMFs and SF act as dispersing and film forming for GNPs, dimensional stability, and interfacial binding agents, respectively. Extraordinarily, by adding SF, graphene nanosheets are tightly coated on the surface of CMFs. The composite paper shows a tensile strength of 49.29 MPa, surface resistance of 39.0-42.1 Ω and good joints bend sensing performance. Additionally, it is found that CMFs can hinder the micro-cracks from propagating during the cyclic elbow bending test. The graphene-based conductive paper is helpful for the development of smart clothing wearable biosensing devices.

Understanding Nanocellulose-Water Interactions: Turning a Detriment into an Asset

Modern technology has enabled the isolation of nanocellulose from plant-based fibers, and the current trend focuses on utilizing nanocellulose in a broad range of sustainable materials applications. Water is generally seen as a detrimental component when in contact with nanocellulose-based materials, just like it is harmful for traditional cellulosic materials such as paper or cardboard. However, water is an integral component in plants, and many applications of nanocellulose already accept the presence of water or make use of it. This review gives a comprehensive account of nanocellulose-water interactions and their repercussions in all key areas of contemporary research: fundamental physical chemistry, chemical modification of nanocellulose, materials applications, and analytical methods to map the water interactions and the effect of water on a nanocellulose matrix.

Fabrication and Properties of Tree-Branched Cellulose Nanofibers (CNFs) via Acid Hydrolysis Assisted with Pre-Disintegration Treatment

In this paper, the novel morphology of cellulose nanofibers (CNFs) with a unique tree-branched structure was discovered by using acid hydrolysis assisted with pre-disintegration treatment from wood pulps. For comparison, the pulps derived from both softwood and hardwood were utilized to extract nanocellulose in order to validate the feasibility of proposed material fabrication technique. The morphology, crystalline structures, chemical structures, and thermal stability of nanocellulose were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetric analysis (TGA). Prior to acid hydrolysis, softwood and hardwood pulps underwent the disintegration treatment in the fiber dissociator. It has been found that nanocellulose derived from disintegrated pulps possesses much longer fiber length (approximately 5-6 μm) and more evident tree-branched structures along with lower degree of crystallinity when compared with those untreated counterparts. The maximum mass loss rate of CNFs takes place at the temperature level of approximately 225 °C, and appears to be higher than that of cellulose nanowhiskers (CNWs), which might be attributed to an induced impact of amorphous content. On the other hand, disintegration treatment is quite beneficial to the enhancement of tensile strength of nanocellulose films. This study elaborates a new route of material fabrication toward the development of well-tailored tree-branched CNFs in order to broaden the potential widespread applications of nanocellulose with diverse morphological structures.

Poly(3-hydroxybutyrate) Nanocomposites with Cellulose Nanocrystals

Poly(3-hydroxybutyrate) (PHB) is one of the most promising substitutes for the petroleum-based polymers used in the packaging and biomedical fields due to its biodegradability, biocompatibility, good stiffness, and strength, along with its good gas-barrier properties. One route to overcome some of the PHB’s weaknesses, such as its slow crystallization, brittleness, modest thermal stability, and low melt strength is the addition of cellulose nanocrystals (CNCs) and the production of PHB/CNCs nanocomposites. Choosing the adequate processing technology for the fabrication of the PHB/CNCs nanocomposites and a suitable surface treatment for the CNCs are key factors in obtaining a good interfacial adhesion, superior thermal stability, and mechanical performances for the resulting nanocomposites. The information provided in this review related to the preparation routes, thermal, mechanical, and barrier properties of the PHB/CNCs nanocomposites may represent a starting point in finding new strategies to reduce the manufacturing costs or to design better technological solutions for the production of these materials at industrial scale. It is outlined in this review that the use of low-value biomass resources in the obtaining of both PHB and CNCs might be a safe track for a circular and bio-based economy. Undoubtedly, the PHB/CNCs nanocomposites will be an important part of a greener future in terms of successful replacement of the conventional plastic materials in many engineering and biomedical applications.

Recent advancement in isolation, processing, characterization and applications of emerging nanocellulose: A review

The emergence of nanocellulose from various natural resources as a promising nanomaterial has been gaining interest for a wide range application. Nanocellulose serves as an excellent candidate since it contributes numerous superior properties and functionalities. In this review, details of the three main nanocellulose categorised: cellulose nanocrystal (CNC), cellulose nanofibril (CNF), and bacterial nanocellulose (BNC) have been described. We focused on the preparation and isolation techniques to produce nanocellulose including alkaline pre-treatment, acid hydrolysis, TEMPO-mediated oxidation, and enzymatic hydrolysis. The surface modification of nanocellulose through esterification, silylation, amidation, phosphorylation, and carboxymethylation to improve the diverse applications has also been reviewed. Some invigorating perspectives on the applications, challenges, and future directions on the relevant issues regarding nanocellulose are also presented.

Structure and Properties of Cellulose/Mycelium Biocomposites

The current environmental problems require the use of low-energy, environmentally friendly methods and nature-like technologies for the creation of materials. In this work, we aim to study the possibility of the direct biotransformation of fibrillar cellulose by fungi through obtaining a cellulose/mycelium-based biocomposite. The cellulose micro- and nanofibrils were used as the main carbon sources in the solid-phase cultivation of basidiomycete Trametes hirsuta. The cellulose fibrils in this process act as a template for growing mycelium with the formation of well-developed net structure. The biotransformation dynamics of cellulose fibrils were studied with the help of scanning electron microscopy. The appearance of nitrogen in the structure of formed fibers was revealed by elemental analysis and FTIR-spectroscopy. The fibers diameters were estimated based on micrograph analysis and the laser diffraction method. It was shown that the diameter of cellulose fibrils can be tuned by fungi through obtaining cellulose-based mycelium fibers with a narrower diameter-size distribution as compared to the pristine cellulose fibrils. The morphology of the resulting mycelium differed when the micro or nanofibrils were used as a substrate.

Utilization of mesoporous phosphotungstic acid in nanocellulose membranes for direct methanol fuel cells

Nanocellulose (NC) composite membranes containing novel ternary materials including NC, imidazole (Im), and mesoporous phosphotungstic acid (m-PTA) were successfully fabricated by a phase inversion method. The single-particle size of NC was 88.79 nm with a spherical form. A m-PTA filler with a mesopore size of 4.89 nm was also successfully synthesized by a self-assembly method. Moreover, the fabricated membrane NC/Im/m-PTA-5 exhibited the best performances towards its proton conductivity and methanol permeability at 31.88 mS cm⁻¹ and 1.74 × 10⁻⁶ cm² s⁻¹, respectively. The membrane selectivity was 1.83 × 10⁴ S cm⁻³.

A NC/Im/m-PTA membrane was fabricated for direct methanol fuel cell applications.

Waste Natural Polymers as Potential Fillers for Biodegradable Latex-Based Composites: A Review

In recent years, biodegradable composites have become important in various fields because of the increasing awareness of the global environment. Waste natural polymers have received much attention as renewable, biodegradable, non-toxic and low-cost filler in polymer composites. In order to exploit the high potential for residual natural loading in latex composites, different types of surface modification techniques have been applied. This review discusses the preparation and characterization of the modified waste natural fillers for latex-based composites. The potency of the waste natural filler for the latex-based composites was explored with a focus on the mechanical, thermal, biodegradability and filler-latex interaction. This review also offers an update on the possible application of the waste natural filler towards the biodegradability of the latex-based composites for a more sustainable future.