Cellulose Composite Films Research Articles

Gellan gum-based functional films integrated with bacterial cellulose and nano-TiO2/CuO improve the shelf life of fresh-cut pepper

Active food packaging materials often possess barrier, hydrophobic and antioxidant properties, which are essential for maintaining food quality and safety. In this study, low acyl gellan gum (LAGG) and high acyl gellan gum (HAGG)-bacterial cellulose (BC) composite films (LAGG-BC and HAGG-BC) were respectively prepared by incorporating BC into LAGG and HAGG. The results showed that the mechanical, barrier properties and stability of the composite films were significantly improved after incorporating with BC. However, LAGG-BC film possessed higher mechanical, hydrophobicity, barrier properties and stability than HAGG-BC film. The structural characterization results indicated that BC and LAGG showed good compatibility and intermolecular interactions, and the formed film was smooth and flat. Furthermore, the added nano-TiO2/CuO further lowered its transparency and enhanced the UV-barrier, antioxidant activity and flexibility. The application experiments proved that LAGG-BC/T-0.4 %CuO film effectively inhibited the softening, reddening, browning and rotting of fresh-cut peppers during storage, and also provided excellent anti-fogging, bending and thermal reversibility properties. Thus, LAGG-BC/T-0.4 %CuO film could be used as a packaging material for fruits and vegetables preservation.

Self-chargeable supercapacitor made with MXene-bacterial cellulose nanofiber composite for wearable devices

The development of wearable electronics is restricted by the developments of supporting energy storage devices, especially flexible supercapacitors. Nowadays, miniaturized supercapacitors based on MXenes due to their obvious advantages in the specific capacity have received extensive attention. The energy existing in the surrounding environment has been used to directly charge energy storage devices. However, the hybrid wearable electronics integrated supercapacitors are mechanically connected through metal wires leading to non-compact devices. Thus, it is urgent to develop a general and universal method to fabricate high-performance robust MXene-based flexible electrodes with high electrical conductivity and apply them to self-chargeable supercapacitors and compact wearable devices. Herein, the bacterial cellulose (BC) nanofibers are used as a crosslinking agent to connect two-dimensional MXene nanosheets through the hydrogen bond, which greatly improves the mechanical strength of MXene-bacterial cellulose (MXene-BC) composite films (Young's modulus reaching 6.8 GPa). The supercapacitors made with the electrodes of MXene-BC composite films (BC content is 10%) present high capacitance behavior (areal capacitance up to 346 mF cm−2) because the introduction of BC nanofibers increases the interlayer spacing of MXene nanosheets, providing more storage space for the ions in the electrolyte. Then, a self-chargeable supercapacitor is proposed based on the combination of a zinc-air (Zn-air) battery and a supercapacitor. The self-chargeable supercapacitor can realize self-charging after dropping a drop of electrolyte solution into the Zn-air battery. The charging voltage of a single self-chargeable supercapacitor can reach 0.6 V after adding artificial sweat as the electrolyte. Finally, a smart wristband with the function of self-charging is proposed, which can absorb the sweat generated by the human for self-chargeable supercapacitors to drive the pedometer integrated within the smart wristband to work. The proposed self-chargeable supercapacitors are simple and effective, not restricted by the use environment, providing a promising way for self-powered wearable electronics.

Significantly thermally conductive cellulose composite film with graphene/boron nitride heterojunction structure achieved by combustion synthesis

Boron nitride nanosheets (BNNSs) have been regarded as promising fillers to fabricate polymer-based composites for thermal management. However, the thermal resistance between BNNSs seriously restricts the further improvement of thermal conductivity (TC) for BNNS-based polymer composites. Herein, a rapid and high-yield method based on a combustion synthesis technique is developed to combine BNNSs and graphene (G) tightly as a hybrid filler, in which G was in-situ grown on the surface and interlayer of BNNSs, forming a special G@BNNS heterojunction structure. A foldable and thermal conductive composite film made of such G@BNNS filler and cellulose nanofiber (CNF) matrixes through filtration exhibits high in-plane and through-plane TC of 125.0 and 2.1 W/(m K), respectively. Such high TC is attributed to the reduced interfacial thermal resistance because of the high order and strong bridging effect of G with BNNSs. By utilizing this composite film as a heat spreader, heat dissipation is demonstrated effectively in high-power LED devices under high-power conditions over numerous cycles and heat dissipation can be carried out uniformly in the in-plane direction. Our findings indicate that G@BNNS/CNF films can meet both performance of maintenance and heat dissipation for thermal management, which are much needed for modern electronic devices.

Facile surface modification of fly ash to obtain flexible cellulose composite dielectric films with enhanced breakdown strength and energy storage density

Facile surface modification of fly ash to obtain flexible cellulose composite dielectric films with enhanced breakdown strength and energy storage density

A Comparative Investigation of the Surface Properties of Corn-Starch-Microfibrillated Cellulose Composite Films.

Starch-based materials seem to be an excellent alternative for conventional plastics used in various applications. Microfibralted cellulose can be used to improve the surface properties of starch-based materials. This study aims to analyze the surface properties of starch-microfibrillated cellulose materials. The surface properties of films were evaluated by ATR-FTIR, surface roughness, water wettability, and surface free energy. The surface homogeneity between corn starch and microfibrillated cellulose (MFC) fibers was confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Microscopic analyses of the film surfaces confirm good compatibility of starch and MFC. The addition of MFC increased the surface roughness and polarity of developed starch/MFC materials. The surface roughness parameter has increased from 1.44 ± 0.59 to 2.32 ± 1.13 for pure starch-based materials and starch/MFC material with the highest MFC content. The WCA contact angle has decreased from 70.3 ± 2.4 to 39.1 ± 1.0°, while the surface free energy is 46.2 ± 3.4 to 66.2 ± 1.5 mJ·m-2, respectively. The findings of this study present that surface structure starch/MFC films exhibit homogeneity, which would be helpful in the application of MFC/starch materials for biodegradable packaging purposes.

Fabrication of carboxymethyl chitosan/oxidized carboxymethyl cellulose composite film and its assessment for coating preservation of strawberry

In the current study, a novel chitosan-based composite, carboxymethyl chitosan (CMCHS)/oxidized carboxymethyl cellulose (OCMC) was fabricated and characterized. The composite film (CMCHS 1.5%w/v+OCMC 0.8%w/v) was more uniform and had better tensile properties, UV blocking, water vapor permeability, and antifungal properties than pure CMCHS film. Preservation experiments showed that the CMCHS/OCMC film was more efficient for retaining the quality decrease of strawberry during storage. By the end of 7 days' storage, the hardness, contents of organic acid, soluble solids, and reducing sugar of coated strawberries were increased by 35.1%, 38.5%, 14.1%, and 3.5%, respectively, compared to the control group; and the decay rate of strawberries in CMCHS/OCMC group also dropped to 36%, about 42% decrease than that in control, suggesting the promising application of CMCHS/OCMC composite in coating preservation.

Surface Engineering of Regenerated Cellulose Nanocomposite Films with High Strength, Ultraviolet Resistance, and a Hydrophobic Surface

Regenerated cellulose packaging materials can alleviate the environmental pollution and carbon emissions caused by conventional plastics and other chemicals. They require regenerated cellulose films with good barrier properties, such as strong water resistance. Herein, using an environmentally friendly solvent at room temperature, a straightforward procedure for synthesizing these regenerated cellulose (RC) films, with excellent barrier properties and doping with nano-SiO2, is presented. After the surface silanization modification, the obtained nanocomposite films exhibited a hydrophobic surface (HRC), in which the nano-SiO2 provided a high mechanical strength, whereas octadecyltrichlorosilane (OTS) provided hydrophobic long-chain alkanes. The contents of the nano-SiO2 and the concentrations of the OTS/n-hexane in regenerated cellulose composite films are crucial, as they define its morphological structure, tensile strength, UV-shielding ability, and the other performance of these composite films. When the nano-SiO2 content was 6%, the tensile stress of the composite film (RC6) increased by 41.2%, the maximum tensile stress was 77.22 MPa, and the strain-at-break was 14%. Meanwhile, the HRC films had more superior multifunctional integrations of tensile strength (73.91 MPa), hydrophobicity (HRC WCA = 143.8°), UV resistance (>95%), and oxygen barrier properties (5.41 × 10-11 mL·cm/m2·s·Pa) than the previously reported regenerated cellulose films in packaging materials. Moreover, the modified regenerated cellulose films could biodegrade entirely in soil. These results provide an experimental basis for preparing regenerated-cellulose-based nanocomposite films that exhibit a high performance in packaging applications.

Multifunctional nanofibrillated cellulose/ZnO@rGO composite films for thermal conductivity, electrical insulation, and antibacterial applications

Polymers are widely applied in electronic equipment due to their comprehensive performance. However, the poor thermal conductivity (TC) limits their application in thermal management. In this paper, a series of multifunctional nanofibrillated Cellulose (NFC) composite films with high TC, electrical insulation, and excellent antibacterial properties were prepared by using zinc oxide@reduced graphene oxide (ZnO@rGO) as the fillers. The results show that a thermal conduction pathway is effectively constructed in the NFC/ZnO@rGO composite films with high in-plane TC of 8.07 W·m−1·K−1, far exceeding the 1.10 W·m−1·K−1 of pure NFC film. The insulated ZnO loaded on the surface of rGO cuts off the formation of a conductive path, so that the composite films retain the original electrical insulation (ρs > 1014 Ω, ρv > 1014 Ω·m). Moreover, the composite films exhibit excellent antibacterial properties because of ZnO. Therefore, the multifunctional NFC-based composite films could be applied in various thermal management systems with different requirements.

Green seaweed (Ulva ohnoi) as a new eco-friendly source for preparing transparent and functional regenerated cellulose composite films

Green seaweed (Ulva ohnoi) as a new eco-friendly source for preparing transparent and functional regenerated cellulose composite films

Flexible cellulose composite film incorporated by carbon nitride@graphene oxide prepared by a “compressed-aerogel” approach for efficient thermal management

Heat dissipation films originating from polymer composite with improved thermal conductivity are becoming potential candidates for effective thermal management of next-generation electronic products, profiting from their soft nature and good electrical insulation. In this work, a novel hybrid filler composed of carbon nitride (C3N4) and graphene oxide (GO) is synthesized and further introduced into the cellulose matrix. The electrical insulation of the composite is maintained, attributed to the low electrical conductivity of C3N4. Meanwhile, the bridged chemical bond between C3N4 and GO reduces the interfacial thermal resistance and promotes heat transfer. By hot-pressing the aerogel intermediate, the directional arrangement of fillers is achieved, leading to favorable flexibility and mechanical behavior, and superior in-plane thermal conductivity (5.74 W/mK) of the composite. Thermal characterizations reveal that lower thermal contact resistance (TCR), improved thermal stability, and the relatively lower coefficient of thermal expansion (CTE) together facilitate its practical application in thermal management. The practical performance test is also performed which fully demonstrates its favorable temperature regulation ability, reflected by a 2.7 °C temperature decrement observed in the cell phone battery heat dissipation test.

Silver nanoparticle-decorated AlN whiskers hybrids for enhancing the thermal conductivity of nanofibrillated cellulose composite films.

By depositing silver nanoparticles (AgNPs) on the surface of aluminum nitride whiskers (AlNw), an AlNw-AgNPs heterogeneous structural filler was rationally designed from the perspective of interface engineering, which was further combined with nanofibrillated cellulose (NFC) to prepare anisotropic composite films by a facile vacuum-assited filtration method. Due to the synergistic effect of cross-linking AlNw and "thermal conducting micro-bridges" of AgNPs, the composite films exhibited an extraordinary in-plane thermal conductivity of 31.329 W m-1 K-1, showing a promising application as thermal management materials.

Preparation and characterization of chitosan/bacterial cellulose composite biodegradable films combined with curcumin and its application on preservation of strawberries

We provided in detail a simple and environmentally-friendly method to prepare a biodegradable composite film using chitosan (CS) and bacterial cellulose (BC) with excellent dispersion. CS was grafted onto BC by Schiff base reaction firstly, and then obtained the nano-sized fibrils by ultrasonic dispersion process (CS-OBC). Different concentrations of curcumin (Cur, 0 %, 0.1 %, 0.3 %, 0.5 %, and 0.7 %, w/v) were incorporated into CS-OBC composite films prepared with optimal film-forming parameters. Mechanical and antioxidant properties, including moisture content, water solubility, and contact angles, were evaluated to determine the effects of Cur addition on the composite films (CS-OBC-Cur). It was found that Cur addition increased the hydrophobicity and oxygen permeability of the film, and that the CS-OBC-0.5%Cur active film exhibited excellent barrier properties, hydrophobicity, and mechanical properties. In addition, polyphenol release was retarded when the active film was in a simulated fat system. The film showed superior preservation of strawberries compared with ordinary PE film and significantly slowed the oxidation of edible oils. These results suggest that CS-OBC-Cur films are a promising food packaging material.

Preparation of microcrystalline cellulose from agricultural residues and their application as polylactic acid/microcrystalline cellulose composite films for the preservation of Lanzhou lily

Microcrystalline celluloses were isolated from four agricultural residues, including sweet sorghum stalk, Jerusalem artichoke stalk, grains stillage, and Chinese herb residue, and characterized in terms of physicochemical and structural properties. The obtained microcrystalline celluloses were composited with polylactic acid as a packing film for the preservation of Lanzhou lily. All the agricultural residues-derived microcrystalline celluloses were in cellulose Iβ structure with high purity and good thermal stability. Microcrystalline celluloses from sweet sorghum stalk had a higher degree of polymerization (327) and crystallinity (70.52 %) than others. The preservation effect of lily bulbs packaged by films were significantly improved indicated by the lessened weight loss rate and the meliorative hardness and whiteness, which ascribe to the repressed oxidation reactions. Polylactic acid/microcrystalline cellulose composite films prepared from sweet sorghum straw have been proved the most effective. This work could offer a value-added outlet for agricultural residues to produce microcrystalline celluloses-based biocompatible films for preservation of Lanzhou lily.

Flexible thermoelectric Cu–Se nanowire/methyl cellulose composite films prepared via screen printing technology

Cu–Se nanowires (NWs) have been successfully synthesized by a wet chemical method and then flexible Cu–Se NW/methyl cellulose (MC) composite films have been prepared via a screen printing technology. The thermoelectric properties of the composite films were enhanced by a cold-pressing combining annealing treatment. A power factor of 121.87 μWm−1K−2 has been achieved for the Cu–Se NW/MC composite films at 380 K. A flexible thermoelectric generator (f-TEG) assembled by 4-leg of the as-prepared composite films can generate an output voltage of 0.83 mV and a maximum output power of 6.71 nW at a ΔT = 9.5 K. After being bent for 500 cycles, the resistance change ratio of the f-TEG along the strip length direction was only 3.69%, indicating that the f-TEG has a favorable stability. The screen printing process has many advantages, such as low cost, large-scale production, easy for operation, and therefore, it has a great potential for fabrication of flexible inorganic-organic thermoelectric composite films.

Flexible Thermoelectric Reduced Graphene Oxide/Ag2S/Methyl Cellulose Composite Film Prepared by Screen Printing Process.

As an organic-inorganic thermoelectric composite material, a flexible, reduced graphene oxide (rGO)/silver sulfide (Ag2S)/methyl cellulose (MC) film was fabricated by a two-step method. Firstly, a rGO/Ag2S composite powder was prepared by a chemical synthesis method, and then, the rGO/Ag2S/MC composite film was prepared by a combined screen printing and annealing treatment process. The rGO and rGO/Ag2S composite powders were evenly dispersed in the rGO/Ag2S/MC composite films. A power factor of 115 μW m-1 K-2 at 520 K was acquired for the rGO/Ag2S/MC composite film, which is ~958 times higher than the power factor at 360 K (0.12 μW m-1 K-2), mainly due to the significant increase in the electrical conductivity of the composite film from 0.006 S/cm to 210.18 S/cm as the test temperature raised from 360 K to 520 K. The as-prepared rGO/Ag2S/MC composite film has a good flexibility, which shows a huge potential for the application of flexible, wearable electronics.

Facile fabrication of flexible and ultrathin self-assembled Ti3C2Tx/bacterial cellulose composite films with multifunctional electromagnetic shielding and photothermal conversion performances

With the rapid development of modern electronics, the next generation of electromagnetic interference (EMI) shielding materials requires ultrathin, lightweight, flexibility and robustness to protect electronic devices from radiation pollution. In this study, the multifunctional Ti3C2Tx/Bacterial Cellulose (Ti3C2Tx/BC) composite films with uniformly lamellar structures have been developed by combining experimental and theoretical works. The microstructures, mechanical properties, EMI shielding and photothermal conversion performances of Ti3C2Tx/BC composite films have been systematically investigated. It is highlighted that the resultant ultrathin and flexible Ti3C2Tx/BC composite film with a Ti3C2Tx content of 50 wt% exhibits satisfactory tensile strength of 109.6 ± 4.5 MPa, excellent electrical conductivity of 5020 S m−1 and EMI SE value of 43.7 dB. More interestingly, the composite film displays stable and fast-response photothermal characteristics, with the photothermal conversion temperature up to 74.5 ℃. This study proposes a versatile strategy to synthesize multifunctional MXene/BC composite films with satisfactory mechanical properties, high performance EMI shielding and photothermal conversion effects, which shows great potential for the protection of electronic devices.

Simultaneous strengthening and toughening lignin/cellulose nanofibril composite films: Effects from flexible hydrogen bonds

Inspired by the lignin-cellulose network in natural wood, we developed a strategy to produce cellulose nanofibril (CNF) composite films using lignin nanoparticles (LNPs) with varied contents of phenolic hydroxyl (Ph-OH) groups as a reinforcing agent. Regulated LNPs with lower molecular weight, higher Ph-OH content, and uniform morphology were successfully prepared by phenolation and anti-solvent precipitation. CNFs mixed with phenolated LNPs of high Ph-OH content (8.23 mmol/g) exhibited a higher tensile strength (∼190 MPa), increased toughness (∼15 MJ/m3), and enhanced UV-blocking ability (∼99 %) compared to lignin-free CNFs and CNF composites with lower Ph-OH content. Thus, hydrogen bonds between Ph-OH groups on lignin and hydroxyl groups on CNFs are vital for enhancing the mechanical strength of composite films. Similar enhanced mechanical properties were found by adding phenolated LNPs into polyvinyl alcohol as a fortifier. This study provides novel insights into producing lignin-reinforced cellulose composite films with UV shielding, thermal stability, and biodegradability.

The Improved Properties of Carboxymethyl Bacterial Cellulose Films with Thickening and Plasticizing

This study aims to improve the thermal stability and mechanical properties of carboxymethyl bacterial cellulose (CMBC) composite films. Experiments were conducted by preparing bacterial cellulose (BC) into CMBC, then parametrically mixing sodium alginate/starch/xanthan gum/gelatin and glycerin/sorbitol/PEG 400/PEG 6000 with CMBC to form the film. Scanning electron microscopy, X-ray diffractometry, infrared spectroscopy, mechanical tests, and thermogravimetric analysis showed that the composite films had better mechanical properties and thermal stability with the addition of 1.5% CMBC (% v/v), 1% sodium alginate, and 0.4% glycerin. Tensile strength was 38.13 MPa, the elongation at break was 13.4%, the kinematic viscosity of the film solution was 257.3 mm2/s, the opacity was 4.76 A/mm, the water vapor permeability was 11.85%, and the pyrolysis residue was 45%. The potential causes for the differences in the performance of the composite films were discussed and compared, leading to the conclusion that CMBC/Sodium alginate (SA)/glycerin (GL) had the best thermal stability and mechanical properties.

Development of xanthan gum/hydroxypropyl methyl cellulose composite films incorporating tea polyphenol and its application on fresh-cut green bell peppers preservation

The aim of this work was to develop an edible packaging material with good performance that can be used for fresh-cut vegetables preservation. The xanthan (XG)-hydroxypropyl methylcellulose (HPMC)-tea polyphenols (TP) composite film (XHT) was prepared by adding TP to the composite film-forming solution of XG and HPMC. At optimum TP dosage of 6% (XHT6), the tensile strength and elongation at break were at the maximum. The antioxidant activity and antibacterial properties were also enhanced, demonstrated good inhibitory ability to Staphylococcus aureus. After 8 days, the amount of Vitamin C that was retained by XHT6 was 127.81% and 7.83% higher than unpackaged and XHT0, respectively. Additionally, the MDA content in green peppers were 39.16% and 78.87% higher than that of unpackaged and XHT0, respectively. Practical applications of XHT films in preserving fresh-cut bell peppers had also shown positive results, making it possible as potential food packaging.

Efficient preparation of all cellulose composite films using a plasticizing-rolling method

Efficient manufacturing cellulose is a promising solution to solve severe environmental problems resulted from non-degradable plastics. Herein, we propose a plasticizing-rolling technique to manufacture cellulose featuring high cellulose ratios (50 wt%) and low temperature (65 °C). Plasticization effect from plasticizers (BmimCl and LiCl) uniformly plasticizes cellulose while shear effect from rolling destroys the crystal area of cellulose, both increasing the mobility of cellulosic molecular chains. SEM images and XRD analysis reveal prepared films are all cellulose composite (ACC), cellulose I in the core area and cellulose II in the surface area. ACC films have high transparency (81 %), tensile strength (73.6 ± 4.8 MPa), and thermal stability. The relationship of structure and properties of ACC films was also discussed and a particle–matrix composite model was proposed to analyze high transparency of ACC films. In conclusion, the proposed method presents a potential to efficiently produce high-performance cellulose materials at large scale.