Search Results (36)

The environmental impact of petroleum-based plastics has driven a global shift toward sustainable alternatives like biodegradable polymers, including polylactic acid (PLA), polybutylene succinate (PBS), and polycaprolactone (PCL). Yet, these bioplastics often face limitations in mechanical and thermal properties, hindering broader use. Reinforcement with cellulose nanofibrils (CNFs) has shown promise, yet most research focuses on conventional sources like wood pulp and cotton, neglecting agricultural residues. This review addresses the potential of maize husk, a lignocellulosic waste abundant in South Africa, as a source of CNFs. It evaluates the literature on the structure, extraction, characterisation, and integration of maize husk-derived CNFs into biodegradable polymers. The review examines the chemical composition, extraction methods, and key physicochemical properties that affect performance when blended with PLA, PBS, or PCL. However, high lignin content and heterogeneity pose extraction and dispersion challenges. Optimised maize husk CNFs can enhance the mechanical strength, barrier properties, and thermal resistance of biopolymer systems. This review highlights potential applications in packaging, biomedical, and agricultural sectors, aligning with South African bioeconomic goals. It concludes by identifying research priorities for improving compatibility and processing at an industrial scale, paving the way for maize husk CNFs as effective, locally sourced reinforcements in green material innovation. Full article

Cellulose-based aerogel is an environmentally friendly multifunctional material that is renewable, biodegradable, and easily surface-modified. However, due to its flammability, cellulose serves as an ignition source in fire incidents, leading to the combustion of building materials and resulting in significant economic losses and safety risks. Consequently, it is essential to develop cellulose-based building materials with flame-retardant properties. Initially, a porous cellulose-based flame-retardant aerogel was successfully synthesized through freeze-drying, utilizing lignocellulose as the raw material. Subsequently, phosphorylation of cellulose was coupled with Ca²⁺ cross-linking via self-assembly and surface deposition effects to enhance its flame-retardant properties. Finally, the synthesized materials were characterized using infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, mechanical compression testing, and scanning electron microscopy. The aerogel of the phosphorylated cellulose nanofibrils cross-linked via 1.5% CaCl₂ exhibited the most effective flame-retardant properties and the best mechanical characteristics, achieving a UL-94 test rating of V-0 and a maximum flame-retardant rate of 90.6%. Additionally, its compressive strength and elastic modulus were recorded at 0.39 and 0.98 MPa, respectively. The preparation process is environmentally friendly, yielding products that demonstrate significant flame-retardant effects and are non-toxic. This product is anticipated to replace polymer-based commercial aerogel materials, representing a sustainable solution to the issue of “white pollution”. Full article

This study compared the use of cellulose nanofibrils (CNF) and lignocellulose nanofibrils (LCNF) in different concentrations to reinforce the poly(vinyl alcohol) (PVA) matrix. Both nanofillers significantly improved the elastic modulus and tensile strength of PVA biocomposite films. The optimum concentration of CNF and LCNF was 6% relative to PVA, which improved the tensile strength of the final PVA biocomposite with CNF and LCNF by 53% and 39%, respectively, compared to the neat PVA film. The addition of LCNF resulted in more elastic films than the addition of CNF to the PVA matrix. The elongation at break of the PVA biocomposite with 2% of LCNF was more than 100% higher than that of the neat PVA film. The integration of tannic acid (TA) into the PVA-LCNF system resulted in antioxidant-active and more water-resistant PVA biocomposites. The three-component biocomposite films with 2 and 6% LCNF and 10% TA exhibited a more than 20° higher contact angle of the water droplet on the surfaces of the biocomposite films and absorbed more than 50% less water than the neat PVA film. New formulations of biocomposite films have been developed with the addition of LCNF and TA in a polymeric PVA matrix. Full article

Biobased foams have the potential to serve as eco-friendly alternatives to petroleum-based foams, provided they achieve comparable thermomechanical and physical properties. We propose a facile approach to fabricate eco-friendly cellulose nanofibril (CNF)-reinforced thermomechanical pulp (TMP) fiber-based foams via an oven-drying process with thermal conductivity as low as 0.036 W/(m·K) at a 34.4 kg/m³ density. Acrodur^®, iron chloride (FeCl₃), and cationic polyacrylamide (CPAM) were used to improve the foam properties. Acrodur^® did not have any significant effect on the foamability and density of the foams. Mechanical, thermal, cushioning, and water absorption properties of the foams were dependent on the density and interactions of the additives with the fibers. Due to their high density, foams with CPAM and FeCl₃ at a 1% additive dosage had significantly higher compressive properties at the expense of slightly higher thermal conductivity. There was slight increase in compressive properties with the addition of Acrodur^®. All additives improved the water stability of the foams, rendering them stable even after 24 h of water absorption. Full article

Coffee is one of the most consumed commodities globally, and its harvests generate large quantities of wood waste with low industrial value. This study aimed to explore the potential of residual Coffea arabica wood to produce lignocellulose microfibrils and lignocellulose nanofibrils (LCMF/LCNF) and biodegradable films with possible application in packaging. The fibers were treated with 5% NaOH and fibrillated in an ultrarefiner until they formed a gel. The resulting suspensions were used to create films whose physical, morphological, optical, and mechanical properties were analyzed. The NaOH treatment removed extractives and exposed hemicelluloses, allowing the gel point to be reached with just seven passes through the ultrarefiner, saving energy (~4700 kWh/t). More than 65% of the fibers had diameters of less than 100 nm and little sedimentation after 8 h. The films were flexible, thin (24.5 µm), with a high density (~1100 kg/m³) and good resistance to grease, as well as a water vapor permeability of ~1230 g/m²/day, suitable for packaging bread, fruit, and vegetables. However, the higher wettability of the surface may limit its use in humid environments. The films showed moderate tensile strength (~25 MPa) but low puncture resistance (~7 N mm), making them suitable for biodegradable packaging. Full article

Bamboo is composed of thick-walled fibrous tissue and thin-walled parenchymal tissue. To compare the energy consumption of preparing lignocellulose nanofibrils (LCNF) from these bamboo tissues, the crystallinity, sol. viscosity, morphology and mechanical properties of LCNF at different preparation stages were characterized in detail. It required at least nine homogenization cycles for dissociating the fibrous tissue, but only six cycles for the parenchymal tissue. The average diameter of LCNF isolated from fibrous and parenchymal tissues was 45.1 nm and 36.2 nm, respectively. The tensile strength of the LCNF film prepared from parenchymal tissue reached 142.46 MPa, whereas the film from fibrous tissue reached only 122.82 MPa. Additionally, a metal organic framework (MOF) was used to produce MOF-LCNF film with enhanced UV protection and antibacterial properties. The results indicated that the energy consumption for preparing LCNF from parenchymal tissue is significantly lower than that for preparing LCNF from fibrous tissue. This study offers a low-cost and eco-friendly method for preparing LCNF, promoting the precise utilization of different tissues from bamboo based on their unique characteristics. Full article

In the present study, an environmentally friendly oil- and water-resistant paper was developed using a holo-lignocellulosic nanofibril (LCNF)-based composite coating. The LCNF was prepared from wheat straw using a biomechanical method. Characterizations of oil- and water-resistant coated paper and the effect of LCNF content on the performance of the coated paper were confirmed by combining contact angle analysis, Cobb 300s, and mechanical performance tests. The results show that the barrier performance and mechanical strength of the coated paper were greatly improved with the increase of LCNF content. The contact angle of oil and water of coated paper containing 50% LCNF were 69° and 78°, respectively, while the contact angle of oil and water of the base paper were only 30° and 20°, respectively. Cobb 300s values reduced from 110 g/m² to 30 g/m² when the LCNF content increased from 50% to 90%. Moreover, under the coating amount of 20 g/m², the tensile strength of the coating paper was 0.980 KN/m, an increase of 10.11% compared with the base paper. The bursting strength reached 701.930 KPa, which was 10.75% higher than the base paper. In short, it is feasible to prepare LCNF from wheat straw, and apply it to produce water-proof and oil-proof paper. The water-proof and oil-proof paper developed in this study not only offers a novel approach to addressing white pollution but also presents a new research avenue for exploring the potential applications of agricultural waste. Full article

Biodegradable mulching films are a very attractive solution to agronomical practices intended to achieve more successful crop results. And, in this context, the employment of agricultural and industrial food residues as starting material for their production is an alternative with economic and environmental advantages. This work reports the preparation of bilayer films having two different wettability characteristics from three bio-derived biopolymers: TEMPO-oxidized cellulose nanofibers isolated from infused Yerba Mate residues, Chitosan and Polylactic acid. The infused Yerba Mate residues, the isolated and oxidized cellulose nanofibers, and the films were characterized. Nanofibrillation yield, optical transmittance, cationic demand, carboxyl content, intrinsic viscosity, degree of polymerization, specific surface area and length were studied for the (ligno)cellulose nanofibers. Textural and chemical analysis, thermal and mechanical properties studies, as well as water and light interactions were included in the characterization of the films. The bilayer films are promising materials to be used as mulching films. Full article

Rice hulls have a high-value potential, and the lignocellulose components are underutilized compared to other biomass resources. Pretreatments such as carboxymethylation of the degree of substitutions (DS) are used to prepare lignocellulose nanofibril (LCNF) from desilicated rice hull (DSRH). High-pressure homogenization (HPH) and grinding are used to process nano fibrillation. The composition of LCNF DS of desilicated rice hull was identified using ¹H NMR for polysaccharide composition and DS determination, acetone and hot water extraction to evaluate extractives, and Klason lignin for lignin content. LCNF was prepared using various DS from 0.2 until DS 0.4. The results showed that LCNF DS has a more than −30 mV zeta potential, suitable for stable nanoemulsion formulations. The particle size of LCNF DS decreases with an increasing carboxyl content in the hydrogel and an increasing number of passes through grinding and high-pressure homogenization, of which LCNF DS 0.4 had the smallest width and length. Mechanical processes further reduced the size. Full article

Lignin-containing nanocellulose fibers (LCNF) have been considered as a valuable enhancer for polyacrylic acid (PAA)-based hydrogels that can form rigid porous network structures and provide abundant polar groups. However, the PAA–LCNF hydrogel is dominated by a single-network (SN) structure, which shows certain limitations when encountering external environments with high loads and large deformations. In this paper, sodium alginate (SA) was introduced into the PAA–LCNF hydrogel network to prepare a double-network (DN) hydrogel structure of the SA-Ca²⁺ and PAA–LCNF through a two-step process. The covalent network of PAA–LCNF acts as the resilient framework of the hydrogel, while the calcium bridging networks of SA, along with the robust hydrogen bonding network within the system, function as sacrificial bonds that dissipate energy and facilitate stress transfer. The resulting hydrogel has porous morphologies. Results show that SA can effectively improve the mechanical properties of DN hydrogels and endow them with excellent thermal stability and electrical conductivity. Compared with pure PAA–LCNF hydrogel, the elongation at break of DN hydrogel increased from 3466% to 5607%. The good electrical conductivity makes it possible to use the flexible sensors based on DN hydrogel to measure electrophysiological signals. Our results can provide a reference for developing multifunctional hydrogels that can withstand ultra large deformation. Full article

Nanofibrillated cellulose was extracted from potato peel waste using a fast and green method with a simple process. To extract cellulose and eliminate non-cellulosic constituents, alkaline and hydrogen peroxide treatments were performed under microwave irradiation. The nanofibrillated cellulose was extracted from purified cellulose via TEMPO oxidation followed by ultrasonication. The TEM, FTIR, XRD, and TGA experiments were used to evaluate the structural, crystalline, and thermal properties of cellulose fiber and nanofiber. The chemical and FTIR analysis of bleached fibers indicates that almost all non-cellulosic components of biomass have been eliminated. The diameter of the extracted nanofibers is in the range of 4 to 22 nm. In terms of crystallinity, extracted nanocellulose had 70% crystallinity, compared to 17% for unprocessed lignocellulose fibers, which makes it an excellent choice for use as a reinforcement phase in biobased composites. Thermogravimetric analysis reveals that cellulose nanofibers are less thermally stable than potato peel pure cellulose, but it has a higher char content (28%) than pure cellulose (6%), which signifies that the carboxylate functionality acts as a flame retardant. The comparison between cellulose derived from microwave and conventional extraction methods confirmed that their impact on the removal of non-cellulosic materials is nearly identical. Full article

Multifunctional biofilms with early fire-warning capabilities are highly necessary for various indoor and outdoor applications, but a rational design of intelligent fire alarm films with strong weather resistance remains a major challenge. Herein, a multiscale hierarchical biofilm based on lignocellulose nanofibrils (LCNFs), carbon nanotubes (CNTs) and TiO₂ was developed through a vacuum-assisted alternate self-assembly and dipping method. Then, an early fire-warning system that changes from an insulating state to a conductive one was designed, relying on the rapid carbonization of LCNFs together with the unique electronic excitation characteristics of TiO₂. Typically, the L-CNT-TiO₂ film exhibited an ultrasensitive fire-response signal of ~0.30 s and a long-term warning time of ~1238 s when a fire disaster was about to occur, demonstrating a reliable fire-alarm performance and promising flame-resistance ability. More importantly, the L-CNT-TiO₂ biofilm also possessed a water contact angle (WCA) of 166 ± 1° and an ultraviolet protection factor (UPF) as high as 2000, resulting in excellent superhydrophobicity, antifouling, self-cleaning as well as incredible anti-ultraviolet (UV) capabilities. This work offers an innovative strategy for developing advanced intelligent films for fire safety and prevention applications, which holds great promise for the field of building materials. Full article

Nanocellulose (NC) is an emerging natural material that offers great potential for various applications due to its unique properties and renewable character. Nowadays, as NC production technologies are advancing, it is essential to evaluate their economic feasibility, technological maturity and commercialization potential using systematic techno-economic analysis (TEA). The present study considers both technical and economic aspects of NC production and analyzes them in two ways: first, by developing a new concept based on the production of different types of NC through the conversion of lignocellulosic biomass by chemical and mechanical technologies, and second, by a comparative review of existing TEA studies in the open literature. Three specific scenarios and two case studies are evaluated by comparing specific key performance indicators (KPIs), such as the production cost (PC) and minimum product selling price (MPSP) of NC. As a result, a short though comprehensive overview of the current state of NC production is provided, highlighting the main technical and economic challenges associated with it. Key areas for future research and innovation (R&I) are also identified to optimize the production processes and reduce relevant costs, in order to make NC competitive with existing materials and realize its full potential. Full article

A new method for extractive-catalytic fractionation of aspen wood to produce microcrystalline (MCC), microfibrillated (MFC), nanofibrilllated (NFC) celluloses, xylan, and ethanollignin is suggested in order to utilize all of the main components of wood biomass. Xylan is obtained with a yield of 10.2 wt.% via aqueous alkali extraction at room temperature. Ethanollignin was obtained with a yield of 11.2 wt.% via extraction with 60% ethanol from the xylan-free wood at 190 °C. The lignocellulose residue formed after the extraction of xylan and ethanollignin was subjected to catalytic peroxide delignification in the acetic acid-water medium at 100 °C in order to obtain microcrystalline cellulose. MCC is hydrolyzed with 56% sulfuric acid and treated with ultrasound to produce microfibrillated cellulose and nanofibrillated cellulose. The yields of MFC and NFC were 14.4 and 19.0 wt.%, respectively. The average hydrodynamic diameter of NFC particles was 36.6 nm, the crystallinity index was 0.86, and the average zeta-potential was 41.5 mV. The composition and structure of xylan, ethanollignin, cellulose product, MCC, MFC, and NFC obtained from aspen wood were characterized using elemental and chemical analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses, Gas chromatography (GC), Gel permeation-chromatography (GPC), Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Dynamic light scattering (DLS), Thermal gravimetric analysis (TGA). Full article

The rising climate change concerns over the excessive exploitation of non-renewable sources have necessitated the need for alternative renewable and eco-friendly resources for the production of innovative materials, achieving the targets of bioeconomy. Lignocellulosic biomass (LB) constituted by polymeric sugars and lignin is an abundantly available plant-based renewable material in the form of agro-industrial food waste and crop residues that can be exploited for the production of an array of value-added chemicals and bioproducts. Cellulose is the most abundant natural and biodegradable organic polymer on earth derived from LB, with wide scale applications in the lignocellulosic biorefineries and food industries. The negative effects of food waste from agro-industrial activities could be reduced through the recovery of cellulose from these wastes and converting it into valuable forms. However, the extraction of cellulose from LB is a difficult task owing to the recalcitrant nature of biomass that restricts the easy accessibility of cellulose for value addition. Therefore, a suitable cellulose extraction method through the fractionation of LB is necessary for a better cellulose yield. Furthermore, owing to the enormous potential of nanocellulose (NC), researchers are keenly interested in developing ecologically acceptable cellulose extraction methods. Cellulose nanofibrils and nanocrystals confer excellent mechanical properties, non-toxic characteristics and biodegradability, due to which they possess wide-scale applications in diverse industrial sectors. The current review emphasizes the potential role of cellulose extraction and NC production from agro-food waste. The different pretreatment methods for their extraction from LB are outlined. The applications of nanocellulose in different areas are also discussed. The review also highlights the recent trends, challenges and future directions in the development of cellulose and NC-based commercial products. Full article