Commercial Cellulose Research Articles

Comparison of the tensile behaviour enhancement of cement paste incorporated with μm- and mm-scale cellulose fibres at the early curing age

In this work, one type of commonly used commercial cellulose fibre with lengths ranging from μm to mm is introduced into cement paste at concentrations of 0.1 wt% to 10 wt% to study its effect on enhancing tensile behaviour and microstructural evolution at the early curing stage. Significantly inhibited hydration due to cellulose fibre incorporation is revealed, and the degree of inhibition increases as the length of the cellulose fibres decreases. Additionally, the degree of hydration calculated by the TGA data of cellulose fibre-incorporated cement paste needs to be calibrated against the mass loss of cellulose fibres during heating because it cannot be directly deduced by the TGA data of pure cellulose fibres. Only mm-scale cellulose fibres significantly improve the post-peak ductility, whereas µm-scale cellulose fibres have a weak enhancement effect on the post-peak ductility. It is found that cellulose fibres at both the μm and mm scales can enhance the tensile strength at day 28. Regarding this type of commercial cellulose fibre, it is optimal to adopt the mm-scale cellulose fibres because of their significant effect on improving tensile behaviour.

Cellulose dialysis membrane tubing doped with gold nanoparticles as SERS substrate

In this study, we report for the first time the use of a dialysis method for simple preparation of a flexible substrate for Surface-Enhanced Raman Spectroscopy (SERS). The method consists of synthesized citrate gold nanoparticles capped with poly(allylamine-hydrochloride), poured into a commercial cellulose dialysis membrane, and set into a glass beaker with water under magnetic stirring for 48 h for dialysis. Then gold nanoparticles doped the cellulose membrane to get a SERS substrate, which was characterized by Raman spectroscopy using 4-Aminothiophenol, and 4-Mercaptobenzoic acid as a Raman probe in the range from 1×10−5 to 1×10−10M, Raman signal as a function of logarithm concentration shows a linear behavior and estimated analytical enhancement factor of the substrate using 4-Aminothiophenol was 4.3×105. The flexibility of our SERS substrate can be helpful in applications where solid SERS substrates have low performance. For example, when the surface needs bending for sample preparation or analysis, cut out into small pieces or washed without losing its SERS properties.

Comparative Analysis of the Cooling Efficiency in Tropical Climate of Three Alternative Materials for Evaporative Cooling Pads

A comparison between commercial cellulose evaporative cooling pad and pads manufactured with three alternative materials was made for environmental conditions typical of tropical countries. Wind tunnel tests were carried out to compute the convective heat and mass transfer coefficients and to measure the pressure drop across each pad, obtaining expressions that can be used as reference for future simulations. Using a mathematical model, a detailed analysis of the efficiency, Temperature–Humidity Index, temperature drop and relative humidity through the pads was performed in terms of different operative and constructive conditions, such as air velocities, dry-bulb temperatures, relative humidity and pad thickness. Significant differences between the pressure drop across the pads were found, which increases with the inlet air velocity and water flow. A weak relation between the analysed variables and the inlet air velocity was found, while a high correlation between the analysed variables, pad thickness and the external environmental conditions was established. Cooling efficiencies above 40% and a Temperature–Humidity Index below the mild zone of thermal stress were obtained for the alternative panels. Although the cellulose cooling pad showed the best behaviour in all aspects, the alternative pads can be used as substituted in specific applications to reduce the Temperature–Humidity Index inside agricultural facilities.

Manipulating Zn-ion flux by two-dimensional porous g-C3N4 nanosheets for dendrite-free zinc metal anode

Zinc metal anode is a promising choice in aqueous zinc ion batteries (ZIBs) due to its high volumetric capacity, low toxicity, and natural abundance. However, zinc dendrite growth severely compromises the practicability of zinc metal anode in large-scale utilizations of ZIBs. As a key component of ZIB, separator plays an important role in regulating zinc ion flux and thus has a direct impact on zinc dendrite growth. However, little attention has been paid on the the effect of separator on dendrite growth. Herein, we report a modified separator by coating a layer of g-C3N4 nanosheets onto commercial cellulose fiber separator via a simple drop casting route. The porous two-dimensional g-C3N4 nanosheets act as ion redistributors to induce homogenous zinc ion flux, thus the g-C3N4 coated separator enables a dendrite-free zinc deposition and improves the reversibility of zinc metal anodes. As a result, the Zn||Zn symmetric cell using the g-C3N4 coated separator exhibits a 300-fold improvement in cycling lifetime of over 590 h at 3 mA cm−2 and the coulombic efficiency of Zn||Cu asymmetric cell with g-C3N4 coated separator maintains at 99.2% at 1 mA cm−2 for over 750 cycles, which are better than most of the reported ZIBs to date.

Super-Repellent Paper Coated with Electrospun Biopolymers and Electrosprayed Silica of Interest in Food Packaging Applications.

In the current work, a super-repellent biopaper suitable for food contact applications was developed. To do this, three different kinds of biopolymers, namely polylactide (PLA), poly(ε-caprolactone) (PCL), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and hydrophobic silica microparticles (SiO2), were sequentially processed by electrohydrodynamic processing (EDHP). As a first step, the ultrathin biopolymer fibers were deposited onto a commercial food contact cellulose paper by electrospinning and, thereafter, the nanostructured silica was sequentially electrosprayed. The multilayer coated papers were annealed at different temperatures to promote adhesion between the layers and enhance the super-repellent properties. The developed coatings were characterized in terms of morphology, permeance to water vapor, adhesion, mechanical resistance, and contact and sliding angle. The resultant multilayer biopapers presented a hierarchical micro/nanostructured surface with an apparent water contact angle (WCA) higher than 155° and sliding angle (SA) lower than 10° for all the tested biopolymers used. Among the different multilayer approaches, it was observed that the paper/PHBV/SiO2 showed the best performance, in terms of water vapor permeance; resistance after the tape peeling-off test; and food super-repelling properties to water, yogurt, and custard. Overall, this study presents the successful generation of super-repellent biopapers coated with PLA, PCL, or PHBV along with hydrophobic silica microparticles and its effectiveness for easy emptying food packaging applications to reduce food waste.

Living Filtration Membranes Demonstrate Antibiofouling Properties

Membrane filters are excellent prospects for increasing global access to safe water; however, they are significantly limited by fouling, particularly biofouling. Fouling plagues membranes by reducing efficiency and increasing maintenance and costs. Biofouling is particularly problematic due to the self-replicating nature of microorganisms and the secretion of extracellular polymeric substances that make the biofilm difficult to remove. Living filtration membranes (LFMs) are a sustainable membrane technology composed of bacterial cellulose and native microorganisms. In this study, natural water from Butte, Montana’s three municipal drinking water sources (Basin Creek Reservoir, Moulton Reservoir, and Big Hole River) was pretreated with a coagulant and used in 400 min bench-scale dead-end filtration tests. Two membranes were compared─an LFM and a commercial mixed cellulose ester (MCE) membrane with a similar nominal pore size. Although the MCE membrane was more hydrophilic and had a smoother surface, surface properties that, in general, may improve fouling resistance for certain particles, a more rapid flux decline and live biomass were observed with the MCE membrane for all three waters. We suggest that the LFM’s resistance to biofouling may be due to the proliferation of native bacteria, Acetobacter, which produces acetic acid, a known antibiofilm and antibacterial agent.

Effect of Cellulose Nanofibers (CNF) as Reinforcement in Polyvinyl Alcohol/CNF Biocomposite

This research was targeted to use the planetary ball milling method to extract cellulose nanofibers (CNFs) from commercial microcrystalline cellulose and also to utilize the obtained extracted cellulose nanofibers (CNFs) as reinforcement in polyvinyl alcohol (PVA) thin film. The effect of cellulose nanofibers (CNFs) on the mechanical and physical properties of polyvinyl alcohol (PVA) thin films was investigated. As a result of the study, we found that the thin film’s tensile strength is good, and the surface morphology of the CNFs suspension enhances the bonding between the PVA and the reinforcement. Tyndall effect was accurate with the visible light scattering through CNF suspension, and the CNF/PVA thin film exhibited transparent thin film. In contrast, the CNF/PVA composite’s mechanical and physical properties are good due to the excellent dispersion and absence of agglomeration of CNFs. The prepared PVA/CNF biocomposite would be a suitable candidate to be implemented as biodegradable food packaging material.

Kinetic Assessment of Mechanical Properties of a Cellulose Board Aged in Mineral Oil and Synthetic Ester.

In oil-immersed power transformers, the insulation system is constituted of a dielectric oil–solid combination. The insulation oil generally used is mineral oil; however, this fluid has started to be substituted by natural and synthetic esters due to their higher biodegradability and flash point. The introduction of a new fluid in the insulation system of power transformers requires kinetic models that can estimate the degradation rate of insulation solids. The aim of this work was to go further in quantifying through different kinetic models the deterioration suffered by a commercial cellulose board (PSP 3055), which is one of the solid materials used in the insulation system of oil-filled transformers. The aging study was extended to cellulose board specimens immersed in two different oils (mineral and synthetic ester). It was obtained that there is a lower degradation when synthetic ester is used in the insulation system. Additionally, it can be concluded that the use of mechanical properties to quantify the degradation of the cellulose board through kinetic models provides information about the different behavior shown by PSP 3055 when different fiber direction angles are considered.

Life Cycle Assessment application for emerging membrane recycling technologies: From reverse osmosis into forward osmosis

Recycling end-of-life (EoL) reverse osmosis (RO) membrane modules into forward osmosis (FO) membranes is an innovative alternative to approach membrane science into Circular Economy (CE). Membrane modules are chemically modified and disassembled. This strategy achieves the valorisation of 69% of the membrane area and 63.7% of the plastic components. This study aims to assess the environmental potential of the above-mentioned recycling strategy. Therefore, a Life Cycle Assessment (LCA) was conducted with a substitution approach. The recycling strategy was compared with commercial Thin Film Composite (TFC) and Cellulose Triacetate (CTA) membranes at two different solution concentrations. To introduce the membrane performance comparison, a substitutability factor (SF) was developed with the flow ratio. OpenLCA 1.7.4 with Ecoinvent v3.4 and ILCD-midpoint and endpoint impact methods were used. The inventories of the commercial membranes were developed through membrane surface characterisation techniques, patents and lab protocols. One critical point during the inventory development was the estimation of solvent losses through BREF documents. However, a sensitivity analysis was performed to evaluate its relevance in decision making. Results pointed out the interest in almost all ILCD-midpoint categories and all the ILCD-endpoint categories. IR-hh, IR-e and Feu Categories were unfavourable coinciding with low environmental credits of the plastic valorisation. Sensitivity analysis identified solvent losses as a source of error.

Cellulose for Sustainable Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) are an emerging technology capable of converting the ambient mechanical energy into electricity, promising for complete utilization of the distributed energy to improve the quality of human life. However, realizing material innovation for good trade‐off between the high triboelectric output and environment friendliness remains huge challenge, but it is of great importance for sustainable development of TENGs. Cellulose is a typical natural polymer that promises to address the challenge. Herein, the sustainable TENGs that originate from cellulose and potentially back to the natural world are focused on, realizing on‐spot TENGs. First, the sources, forms, morphologies, structures, and modifications of cellulose are systematically summarized, indicating the commercial and noncommercial cellulose materials’ potential for TENGs’ application. Second, the dominating additive properties of cellulose such as hydrophobicity, self‐cleaning, corrosion resistance, optical transparency, electrical conductivity, and degradability are introduced, which can effectively steer the development of TENGs. Thereafter, the TENGs with tailorable functions enabled by less‐refined cellulose and various physical/chemical modified cellulose are reviewed, as well as plants‐supported on‐spot TENGs with environment adaptivity and transient property, embracing a sustainable future of versatile cellulose to adapt the distributed network of multiscenario TENGs for energy management and information communication.

Reducing sugar production from spent coffee grounds using microbubble-assisted synthesis of silica acid catalyst

The popularity of coffee as a beverage has led to a large amount of spent coffee waste worldwide, of which spent coffee ground (SCG) is one of the most heavily generated residues. Considering the environmental and social pressure to reduce pollution and increase sustainability, it is important to explore the application of SCGs in the field of renewable energy. Polysaccharides account for the most abundant components in SCGs, mainly including hemicellulose, cellulose, lignin, fat, and dietary fiber. Herein, SCG is utilized as an alternative to commercial cellulose to produce reducing sugars via hydrolysis using a sulfonated silica catalyst. Sulfonated silica catalysts are heterogeneous catalysts with advantages comprising easy separation and high recyclability. In this study, a simple and template-less method to synthesize mesoporous silica substrates by employing an in-situ microbubble generator was developed. The microbubbles generated during silica synthesis enhanced the structural properties and production yield of the silica spheres. The produced silica substrates were subjected by hydrothermal sulfonation, which resulted in a total acid density of 5.49 mmol g−1 and sulfonic acid density of 0.87 mmol g−1. The total reducing sugar yield of 31.4% was achieved by SCG hydrolysis over microbubble-assisted sulfonated silica catalysts (SSCs) at 150 ℃ for 15 h, with C6 sugars including mannose and galactose as the main products. The recyclability of SSCs was determined with a reusability test under identical coffee hydrolysis conditions. A reducing sugar yield of 96% could be maintained, which verified the high chemical structural stability of SSCs during the synthesis employing the bubble generator and hydrothermal sulfonation process. For comparison, the SSCs prepared by stirring at room temperature without a micro-bubble generator showed a relatively lower sugar yield of 24% under the same hydrolysis conditions. Therefore, this novel microbubble-assisted synthesis described herein is a promising economical, eco-friendly, and simple technique for fabricating structural silica templates as catalyst supports for biomass conversion.

Development of a Cellulose-Based Freshness Sensor (II) : Manufacture of Multilayer Freshness Sensor Using Cellulose-based Materials and Evaluation of Its Color Expression

Lately, the increase in consumers’ demand for food packaging safety standards to be followed has spurred a general interest in intelligent packaging technology that can monitor the status of the products in the packaging system. Commercialized sensors can indicate the freshness of food by expressing the colors based on the concentration levels of carbon dioxide (CO₂) in the food item. However, most of the freshness sensors are manufactured from synthetic polymer materials; therefore, it is necessary to develop an eco-friendly freshness sensor that uses biodegradable and recyclable cellulose-based materials.<BR>In this study, a multilayer freshness sensor was manufactured using cellulose-based materials such as commercial filter papers and cellulose nanofibers (CNFs) prepared in a laboratory. The filter paper with small pore size and large number of pores (No. 3) was selected by observing the color change of the immersed filter paper in a pH-sensitive dye, and used as a matrix expressing the specific color according to the CO₂ concentration. The top layer was prepared using enzyme-pretreated CNF (EN-CNF) to make a transparent film, and the middle and bottom layers were prepared using the biowax-coated filter papers with the lowest air permeability due to the largest pore size (No. 4). Finally, a eco-friendly freshness sensor was assembled using the matrix, CNF film, and biowax-coated filter papers, whose color expressions clearly differed based on their CO₂ concentration levels.

Structural engineering on copolyimide membranes for improved gas separation performance

The structural engineering and design of 6FDA/BPDA-based copolyimide membranes at a molecular level are developed to achieve advanced membrane materials with improved CO2 plasticization resistance as well as high gas separation performance. The commercially available diamine monomers with/without various electronegative groups (-CH3, –CF3 and -Cl) have been employed to prepare 6FDA/BPDA-based copolyimides via the one-step method. All of the copolyimides show excellent solubility in the common solvent, film-forming ability and thus mechanical properties. More interestingly, the intermolecular charge transfer complex (CTC) effects is finely tuned as confirmed by the fluorescence emission spectrum. The introducing of polar chloride groups in the copolyimides could significantly strengthen the CTC effects to prevent the intrusion of condensable CO2 and limit polymeric chain movements. Thus, the membrane based on the 2,2′,5,5′-tetrachlorobenzidine (e.g. 6FDA:BPDA-TSN:TCDB (1:1:1:1)) shows the best carbon dioxide (CO2) plasticization resistance and slowest physical aging without sacrificing gas separation performance versus the membrane having weak polar groups. The CO2 plasticization pressure as high as 350 psi has been observed for the 6FDA:BPDA-TSN:TCDB membrane with polar chloride groups. This value is much higher than that of the copolyimide membranes with –CH3 or –CF3 groups ranging from 100 psi to 200 psi. Moreover, this membrane shows a good gas separation performance, e.g. CO2 permeability of 45.7 barrer and CO2/CH4 ideal selectivity of 35.2 surpassing the commercial cellulose acetate and Matrimid. Such structurally defined polymer with good mechanical strength, plasticization resistance and solubility harnesses the full potential of promising gas separation membrane materials for hollow fiber spinning. This work offers structural engineering guidance for the preparation of high-performance polymers with good tolerance to CO2-induced plasticization.

Investigation on the Preparation of Rice Straw-Derived Cellulose Acetate and Its Spinnability for Electrospinning.

Rice straw-derived cellulose (RSC) with purity of 92 wt.% was successfully extracted from rice straw by a novel and facile strategy, which integrated the C2H5OH/H2O autocatalytic process, dilute alkali treatment and H2O2 bleaching process. Influencing factors of the cellulose extraction were systematically examined, such as ethanol concentration, alkali concentration, H2O2 bleaching process and so on; the optimal extraction conditions of cellulose was determined. A series of rice straw-derived cellulose acetate (RSCA) with different degree of substitution (DS) were prepared by the acetylation reaction; the effects of Ac2O/cellulose ratio, reaction temperature and reaction time on the acetylation reaction were investigated. Results of FTIR and XRD analysis demonstrated that highly purified RSC and RSCA were prepared comparing with the commercial cellulose and cellulose acetate. Solubility analysis of RSCA with different DS indicated as-prepared RSCA with DS of 2.82 possessed the best solubleness, which was suitable for electrospinning. Moreover, the flexible RSCA fibrous membrane was easily fabricated by a facile electrospinning method. Our proposed method provided a strategy for realizing the high-value utilization of waste rice straw resource, as prepared RSC and RSCA can be used as chemical raw material, and electrospun RSCA fibrous membrane has various applications in medical materials, food packaging, water purification and so on.

Wet-Spun Composite Filaments from Lignocellulose Nanofibrils/Alginate and Their Physico-Mechanical Properties.

Lignocellulose nanofibrils (LCNFs) with different lignin contents were prepared using choline chloride (ChCl)/lactic acid (LA), deep eutectic solvent (DES) pretreatment, and subsequent mechanical defibrillation. The LCNFs had a diameter of 15.3–18.2 nm, which was similar to the diameter of commercial pure cellulose nanofibrils (PCNFs). The LCNFs and PCNFs were wet-spun in CaCl2 solution for filament fabrication. The addition of sodium alginate (AL) significantly improved the wet-spinnability of the LCNFs. As the AL content increased, the average diameter of the composite filaments increased, and the orientation index decreased. The increase in AL content improved the wet-spinnability of CNFs but deteriorated the tensile properties. The increase in the spinning rate resulted in an increase in the orientation index, which improved the tensile strength and elastic modulus.

Characterization of Cellulose-Chitosan-Based Materials from Different Lignocellulosic Residues Prepared by the Ethanosolv Process and Bleaching Treatment with Hydrogen Peroxide.

Cellulose-based composites are promising biomaterials with potent applications in absorbents, cosmetics, and healthcare industries. In this study, the cellulose fractions from various agricultural residues, including bagasse (BG), rice straw (RS), corncob (CC), and palm fiber (PF), were prepared by the organosolv process using 70% v/v ethanol, followed by bleaching and forming with chitosan powder. Organosolv treatment at 180 °C of BG, RS, and PF and at 190 °C of CC for 60 min using H2SO4 as the catalyst was optimal for high cellulose recovery (87.9–98.9%) with efficient removals of the hemicellulose (59.3–86.0%) and lignin (61.1–73.7%). High cellulose purity in the solids (76.9–86.8%) was obtained after bleaching with 4% v/v H2O2 compared with that of 84.9% for commercial cellulose. The isolated celluloses were incubated with 2% w/v chitosan solution in acetic acid for the formation of the hydrogen-bonding interaction between the cellulose fiber and chitosan. The pieces of evidence of the obtained sheet materials were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction analysis, and thermogravimetric analysis. All cellulose–chitosan materials absorbed water fraction in the range of 54.3–94.2 g/m2. Efficient oil absorption was observed for cellulose–chitosan sheets prepared from PF (96.3 g/m2) and CC (81.1 g/m2). This work demonstrated the preparation of potent biobased absorbents with a promising application in waste treatment and healthcare industries.

Towards regenerated cellulose fibers with high toughness

The production of sustainable and high-performance fabrics requires high mechanical strength of the individual (staple) fibers. Although Ioncell fibers already exhibit higher fiber strength than commercial man-made cellulose fibers or cotton fibers, we further aimed to increase both strength and toughness to gradually approach synthetic fibers in these properties. Decisive factors for the achievable mechanical properties of the fibers were the pulp purity, the cellulose concentration in the spinning solution and length-to-diameter (L/D) ratio of the cylindrical part of the spinneret. The absence of low molecular weight fractions in combination with an increased average molecular weight had the highest impact on the achievement of both high strength and toughness. Using a spinneret with a high L/D ratio, it was possible to spin Ioncell fibers with a tensile strength of 925 MPa (61.5 cN/tex) and a modulus of toughness of 83.3 MPa (55.5 J/g). According to a fluid dynamic simulation, uniformly longer molecular cellulose chains in combination with a longer cylindrical capillary promoted an effective alignment of the cellulose molecules inside the spinneret capillary before entering the airgap, thus creating the conditions for a simultaneous increase in tensile strength and elongation i.e. toughness of the fiber. Mechanistically, high fiber toughness is caused by the structural parameters in longitudinal direction, in particular by a higher tilt angle, a longer periodicity of the lamellar plane and lower micro void orientation. In summary, we have developed lyocell-type fibers with high strength and toughness, which can potentially be used as a surrogate for synthetic fibers.Graphic abstract

Production of photochromic nanocomposite film via spray-coating of rare-earth strontium aluminate for anti-counterfeit applications.

New photochromic film was developed toward the preparation of anti-counterfeiting documents utilizing inorganic/organic nanocomposite enclosing a photoluminescent inorganic pigment and a polyacrylic binder polymer. To generate a translucent film from pigment/polyacrylic nanocomposite, the phosphorescent strontium aluminum oxide pigment should be well-dispersed in the solution of the polyacrylic-based binder without agglomeration. The photochromic nanocomposite was applied efficiently onto commercial cellulose paper documents utilizing the effective and economical spray-coating technology followed with thermofixation. A homogeneous photochromic film was immobilized onto cellulose paper surface to introduce a transparent film changing to greenish-yellow upon exposure to ultraviolet light as depicted by CIE coloration measurements. The photochromic effect was monitored at lowest pigment concentration (0.25 wt%). The spray-coated paper documents exhibit two absorbance bands at 256 and 358 nm, and two fluorescence peaks at 433 and 511 nm. The morphologies of the spray-coated documents were explored. The spray-coated paper sheets showed a reversible photochromic effect without fatigue under ultraviolet irradiation. The rheology of the produced photochromic composites as well as the mechanical properties and photostability of the spray-coated documents were studied.

Performance of photopolymerized active layer forward osmosis membrane in the osmotic microbial fuel cell

Osmotic microbial fuel cell (OMFC) is evolved by substituting the proton exchange membrane (PEM) by forward osmosis (FO) membrane in a microbial fuel cell (MFC). This study tried to mitigate the dependency on commercial FO membranes to enhance the mutual benefits between MFC and FO. We investigated the performance of photo-polymerized active layer FO membranes in OMFC with feed as a synthetic wastewater and draw solution as 35 g/L NaCl solution and compared by commercial HTI cellulose triacetate (CTA) membrane. Poly (ethylene glycol) phenyl ether acrylate (PPEA) monomer and methacrylic acid (MAA) monomer was used in different ratio i.e., 100/0, 75/25, 50/50, 25/75 and 0/100 for preparation of active layer on our earlier work’s optimized substrate. Effect of the concentration of MAA had a significant effect on ion exchange capacity, water uptake, and oxygen and proton mass transfer. Among all prepared membranes, the 75/25 FO membrane showed the highest power density of 237.23 ± 0.90 mW/m 2 and average water flux 0.95 ± 0.71 LMH. • Photo-polymerized active layer FO membranes were investigated in OMFC. • PPEA and MAA were used as monomers to prepared FO membranes. • The concentration of MAA was found a significant parameter. • 75/25 FO membrane showed highest performance than CTA FO membrane.

Bulgur bran as a biopolymer source: Production and characterization of nanocellulose-reinforced hemicellulose-based biodegradable films with decreased water solubility

Bulgur bran is a lignocellulosic side-stream of bulgur production factories. Separation of bulgur bran into cellulose- and hemicellulose-rich fractions paved the way of utilization of this under-exploited agro-industrial biomass. Although hemicellulose-based biodegradable food packaging films provide significant advantages, their high water solubility and low mechanical strength are obstacles to their commercialization. To overcome these bottlenecks, commercial cellulose nanocrystal (CNC) and cellulose nanofiber (CNF) were incorporated into the hemicellulose matrix. Besides, addition of citric acid (CA) was investigated for its plasticizing effect. To minimize the film water solubility (FWS) statistical optimization by Box-Behnken design (BBD) and response surface methodology (RSM) was employed. The proposed full-quadratic model was found to have high accuracy (R2 = 0.9877) within 95 % confidence interval. The results revealed that 10 % (w/w) CNC- and 10 % (w/w) CNF-incorporated films exhibited 21.3 % reduction in FWS compared to neat films. CNC- and CNF-reinforced films showed a compact structure in SEM analysis. CNC and CNF as fillers in the hemicellulose network markedly improved the tensile strength of the films. Nanocellulose incorporation caused a decrease in water vapor permeability (WVP), light transmittance, total color difference and biodegradability of the films. The properties of nanocellulose-reinforced and neat films were also compared using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Presence of nanocelluloses in the films increased the glass transition temperature (Tg) by around 15 °C as shown by DSC analysis.