Poly Vinyl Alcohol Nanocomposite Films Research Articles

Effect of blue light irradiation on the formation of silver nanostructures in polyvinyl alcohol nanocomposite films

Effect of blue light irradiation on the formation of silver nanostructures in polyvinyl alcohol nanocomposite films

Structural, thermal and optoelectrical study of PVA/iron oxide nanocomposite films

AbstractThe work reported here deals with fabricating iron oxide nanoparticles incorporated polyvinyl alcohol nanocomposite films via the solution‐casting green route, characterized using various characterization techniques. X‐ray diffraction analysis shows interaction of nanoparticles with the polyvinyl alcohol matrix, scanning electron microscopy shows surface morphology of crack‐free films, energy dispersive spectroscopy indicates elemental purity, tensiometer analysis shows changing behavior of hydrophilic to hydrophobic, thermogravimetric analysis shows improved thermal stability, ultraviolet‐visible spectroscopy shows tunable optical properties, and frequency response analysis shows improved electrical properties. A small incorporation (1 wt. %) of iron oxide nanoparticles has induced significant alternations in structural, wetting, thermal, optical, and electrical properties of the polyvinyl alcohol‐based nanocomposite films. Results showed notable changes in the structural phases, water contact angle (39.5° to 97.7°), optical absorption edge (5.12 eV to 4.84 eV), indirect band gap (4.99 eV to 4.68 eV), direct bandgap (5.41 eV to 5.21 eV), and band tail (0.57 eV to 0.89 eV) from native polyvinyl alcohol to polyvinyl alcohol/iron oxide nanocomposite films. Enhancements were observed in refractive indices, optical conductivity, optical dielectric loss, thermal stability, dielectric constant, and dielectric loss on incorporating iron oxide nanoparticles into the polyvinyl alcohol matrix. The fabricated nanocomposite films might be a potential material for optoelectronic and microelectronics applications.

Features of nano TiO2 on metallographic and optical performance of polyvinyl alcohol nanocomposite film

Features of nano TiO2 on metallographic and optical performance of polyvinyl alcohol nanocomposite film

Characterization of CNC Nanoparticles Prepared via Ultrasonic-Assisted Spray Drying and Their Application in Composite Films.

The ultrasonic-assisted spray dryer, also known as a nano spray dryer and predominantly used on a lab scale in the pharmaceutical and food industries, enables the production of nanometer-sized particles. In this study, the nano spray dryer was applied to cellulosic materials, such as cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). CNC suspensions were successfully dried, while the CNF suspensions could not be dried, attributable to their longer fibril lengths. The nano spray drying process was performed under different drying conditions, including nebulizer hole sizes, solid concentrations, and gas flow rates. It was confirmed that the individual particle size of nano spray-dried CNCs (nano SDCNCs) decreased as the nebulizer hole sizes and solid contents of the suspensions decreased. The production rate of the nano spray dryer increased with higher solid contents and lower gas flow rates. The resulting nano SDCNCs were added to a polyvinyl alcohol (PVA) matrix as a reinforcing material to evaluate their reinforcement behavior in a plastic matrix using solvent casting. After incorporating the 20 wt.% nano SDCNCs into the PVA matrix, the tensile strength and tensile modulus elasticity of the neat PVA nanocomposite film increased by 22% and 32%, respectively, while preserving the transparency of the films.

Preparation of Nanocellulose from Coffee Pulp and Its Potential as a Polymer Reinforcement.

Coffee is one of the most valued agricultural products regarding its high commercialization rate. During the production of coffee beans, coffee pulp is obtained as one of the main byproducts with a cellulose content of more than 30% of dry weight. This research focused on the value-added potential of coffee pulp fiber as the reinforcement in composite materials. The nanocellulose coffee pulp (NCP) from the coffee pulp (CP) was prepared and subsequently used as a filler to reinforce the polyvinyl alcohol (PVA) matrix for the improvement of PVA composite properties. The CP was treated via alkali and bleaching treatment before the production of NCP using the acid hydrolysis treatment. The TEM result of NCP showed the successful preparation of NCP with an average diameter of 16.03 ± 4.70 nm with increasing crystallinity size and crystallinity index. The effect of glycerol (G) in the PVA matrix was observed. The result showed that glycerol had a play-role as a plasticizer for increased flexibility and decreased hardness and brittleness of PVA nanocomposite film. The nanocomposite film of PVA/G/NCP was fabricated with various ratios of NCP through the casting method. It was shown that the physical properties were improved with the presence of NCP in the PVA matrix compared to the neat PVA film.

Study of dielectric and magnetodielectric behavior of flexible PVA-NiNdxFe2-X O4 film for EMI shielding application

We have reported dielectric and magnetocaloric effects in flexible Neodymium (Nd) doped nickel ferrite (NiNdxFe2-xO4) - polyvinyl-alcohol nanocomposite films. The samples are characterized by X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and broadband dielectric spectroscopy. The dielectric permittivity is enhanced in the composite for a particular filler concentration. The magnetic entropy change decreases by higher doping in the polymer chain. The magnetodielectric coefficient is enhanced in higher frequency and with the rise in doping concentration. The observed skin depth value of the polymer nanocomposite is lower than the film's thickness which is suitable for electromagnetic shielding.

Cellulose nanofibrils and silver nanoparticles enhances the mechanical and antimicrobial properties of polyvinyl alcohol nanocomposite film

Recent findings of microplastics in marine food such as fish, crabs and shrimps necessitate the need to develop biodegradable packaging materials. This study reports on the development of a biodegradable packing material from cellulose nanofibril-polyvinyl alcohol nanocomposite embedded with silver nanoparticles. Microcrystalline cellulose was isolated from sugarcane bagasse via the kraft process followed by conversion of cellulose I to cellulose II using NaOH/urea/water solution. The nanofibrils were then isolated using (2,2,6,6-Tetramethylpiperidin-1-yl) oxyl (TEMPO) and used as a reinforcing element in polyvinyl alcohol composite prepared through solvent casting. The tensile strength, water solubility, optical properties, water vapor permeability and wettability of the prepared films were then evaluated. The antimicrobial potency of the films was evaluated using the disc diffusion antimicrobial assay against selected microorganisms.

Nature-based nanocomposites for adsorption and visible light photocatalytic degradation of methylene blue dye

Demands for sustainable and eco-friendly materials for environmental remediation have increased the interest in bio-reinforced nanocomposites. Herein, novel plant extracts modified polyvinyl alcohol (PVA) nanocomposite films were fabricated using Hemp seeds, St. John's Wort, Rosemary, and Cherry Laurel plants, and their photocatalytic activities were investigated for the photodegradation of Methylene Blue (MB) dye. Besides, bio-reinforced nanocomposites were characterized by various techniques to investigate the influence of plant extracts on the chemical structure, morphology, hardness, and swelling ratio of nanocomposite films. The morphological inspections revealed that as a result of the plant-extract modification, the PVA matrix was reinforced with equiaxed nanoparticles in a size range from 20 to 250 nm. The Shore-D hardness and the water absorption capacities of fabricated bio-reinforced nanocomposites were found to be 1.86 and 1.24 times higher than their neat counterparts, respectively. Both the bio-reinforced nanocomposites films showed considerably enhanced photocatalytic activity for MB dye degradation relative to neat PVA film. With a synergetic effect of adsorption and photocatalytic degradation, 61.3% of MB dye could be removed under light irradiation by Rosemary and Cherry Laurel modified PVA nanocomposite film. Therefore, the present bio-reinforced nanocomposites with photocatalytic activity shed light on the unknown potential of plant extracts.

Turbostratic Boron-Carbon-Nitrogen and Boron Nitride by Flash Joule Heating.

Turbostratic layers in 2D materials have an interlayer misalignment. The lack of alignment expands the intrinsic interlayer distances and weakens the optical and electronic interactions between adjacent layers. This introduces properties distinct from those structures with well-aligned lattices and strong coupling interactions. However, direct and rapid synthesis of turbostratic materials remains a challenge owing to their thermodynamically metastable properties. Here, a flash Joule heating (FJH) method to achieve bulk synthesis of boron-carbon-nitrogen ternary compounds with turbostratic structures by a kinetically controlled ultrafast cooling process that takes place within milliseconds (103 to104 K s-1 ) is reported. Theoretical calculations support the existence of turbostratic structures and provide estimates of the energy barriers with respect to conversion into the corresponding well-aligned counterparts. When using non-carbon conductive additives, a direct synthesis of boron nitride is possible. The turbostratic nature facilitates mechanical exfoliation and more stable dispersions. Accordingly, the addition of flash products to a poly(vinyl alcohol) nanocomposite film coating a copper surface greatly improves the copper's resistance to corrosion in 0.5 m sulfuric acid or 3.5 wt% saline solution. FJH allows the use of bulk materials as reactants and provides a rapid approach to large quantities of the hitherto hard-to-access turbostratic materials.

PANI-SWCNT Blends with PVA Nanocomposite Films: Structural, Morphological and Electrical Properties for Effective EMI Shielding Applications

Hybrids of Polyaniline-Single walled carbon nanotube (PANI-SWCNT) nanocomposites were synthesized by in situ polymerization and are embedded in the polyvinyl alcohol (PVA) matrix to form nanocomposite films. X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR), and Field Emission Scanning Electron Microscopy (FESEM) were used to study structural and morphological properties which confirm the phase formation, characteristic infrared spectrum and surface morphology of the prepared films. Electrical, dielectric and electromagnetic properties were analyzed and found to enhance with increase of SWCNT in the films. The 3 wt% SWCNT loading film showed the highest AC conductivity with 18.37 × 10−5 S m−1 and maximum shielding effectiveness of 22.73 dB in X-band (8.2–12.4 GHz) region, among all other samples.

Investigation on Reinforcement Effects of Nanocellulose on the Mechanical Properties, Water Absorption Capacity, Biodegradability, Optical Properties, and Thermal Stability of a Polyvinyl Alcohol Nanocomposite Film

This paper presents the reinforcement of nanocellulose (NC) in polyvinyl alcohol (PVA) to examine the effect of the amount of reinforcement on the properties of PVA. The nanocellulose was successfully extracted by sulfuric acid hydrolysis method and ultrasonication, and successively reinforced with polyvinyl alcohol by the solvent-casting method. After incorporating nanocellulose into the PVA matrix, the effect of nanocellulose on the tensile strength, elongation at break, water absorption capacity, transmittance, thermal stability, and biodegradability of PVA was investigated. The tensile strength increased from 24.5 ± 0.53 MPa to 35.5 ± 0.55 MPa and 40.6 ± 0.73 MPa with the addition of 2%NC and 5%NC, respectively. The elongation at break increased from 40 ± 0.53 % to 45.7 ± 0.53 % with 2%NC, and after the reinforcement of 7%NC, it decreased to 32.2 ± 0.75 % . The water absorption capacity result reveals that neat PVA absorbs the highest amount of water which is 84.6 ± 0.56 % and is reduced to 73 ± 0.78 % by adding 2%NC. By increasing the nanocellulose loading to 7%, the water intake capacity was reduced to 61 ± 0.59 % which illustrates the water intake was reduced linearly with the increment of NC. The ultraviolet-visible (UV-Vis) result implies that the transmittance of neat PVA and PVA-2%NC composite film was 85.4% and 78.2% at 600 nm, respectively, which indicates the decrement in transmittance. The thermogravimetry analysis (TGA) reveals that the thermal stability of polyvinyl alcohol after incorporating nanocellulose particles was reduced. The weight loss of neat PVA is 70.7 ± 1.7 % after 90 days while the weight loss of the PVA composite films reinforced with 1%, 3%, 5%, 7%, and 9% was 65 ± 1.85 % , 57 ± 1.57 % , 55.6 ± 0.64 % , 52 ± 1.73 % , and 53.1 ± 1.72 % , respectively. The scanning electron microscopy micrograph for the PVA-6%NC nanocomposite film reveals a dispersion of nanocellulose in a matrix.

Preparation and spectroscopic studies of ZnO incorporated PVA nanocomposite films

Incorporation of zinc oxide nanoparticles (ZnO NPs) into a polyvinyl alcohol (PVA) base matrix forms its nanocomposite films. Their morphological, spectroscopic, and thermal properties were studied using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Ultraviolet–visible Spectrophotometry (UV–vis) spectroscopy, and Differential Scanning Calorimetry (DSC) methods. In this investigation, various weight percentages (0, 2, 4, 6, and 8 wt%) of ZnO NPs were incorporated into PVA using the solution casting method. According to XRD studies, the ZnO nanoparticles' original structure was preserved in the Polyvinyl alcohol–Zinc oxide nanocomposite (PVA-ZnO NC) films, and the crystallinity of the PVA-ZnO NC films was increased. The SEM images confirmed that the ZnO NPs were uniformly spread on the surface film. The UV–visible investigations were carried out, and the values of the refractive index, Urbach energy, direct bandgap, and indirect bandgap were assessed. The loading of 0 to 8 wt% of ZnO NPs in the PVA matrix resulted in a significant change in direct bandgap from 6.16 eV to 5.61 eV, indirect bandgap from 5.89 eV to 5.24 eV, Urbach energy from 0.428 eV to 0.538 eV, linear refractive index from 1.64 to 2.67, and extinction coefficient from 0.00016 to 0.00065. These results showed that the spectroscopic properties of PVA-ZnO NC films were modified considerably with small loadings of ZnO NPs in the PVA matrix due to cross-linking formation between the nanoparticles and the polymer. The DSC results demonstrated that increasing the weight percentage of ZnO NPs had no effect on the glass transition temperature or melting point of the composite films.

Sandwich-Structured, Hydrophobic, Nanocellulose-Reinforced Polyvinyl Alcohol as an Alternative Straw Material.

An environmentally friendly, hydrophobic polyvinyl alcohol (PVA) film was developed as an alternative to commercial straws for mitigating the issue of plastic waste. Nontoxic and biodegradable cellulose nanocrystals (CNCs) and nanofibers (CNFs) were used to prepare PVA nanocomposite films by blade coating and solution casting. Double-sided solution casting of polyethylene-glycol–poly(lactic acid) (PEG–PLA) + neat PLA hydrophobic films was performed, which was followed by heat treatment at different temperatures and durations to hydrophobize the PVA composite films. The hydrophobic characteristics of the prepared composite films and a commercial straw were compared. The PVA nanocomposite films exhibited enhanced water vapor barrier and thermal properties owing to the hydrogen bonds and van der Waals forces between the substrate and the fillers. In the sandwich-structured PVA-based hydrophobic composite films, the crystallinity of PLA was increased by adjusting the temperature and duration of heat treatment, which significantly improved their contact angle and water vapor barrier. Finally, the initial contact angle and contact duration (at the contact angle of 20°) increased by 35% and 40%, respectively, which was a significant increase in the service life of the biodegradable material-based straw.

Lignin-Cellulose Nanocrystals from Hemp Hurd as Light-Coloured Ultraviolet (UV) Functional Filler for Enhanced Performance of Polyvinyl Alcohol Nanocomposite Films.

Lignin is a natural light-coloured ultraviolet (UV) absorber; however, conventional extraction processes usually darken its colour and could be detrimental to its UV-shielding ability. In this study, a sustainable way of fabricating lignin–cellulose nanocrystals (L-CNCs) from hemp hurd is proposed. A homogeneous morphology of the hemp particles was achieved by ball milling, and L-CNCs with high aspect ratio were obtained through mild acid hydrolysis on the ball-milled particles. The L-CNCs were used as filler in polyvinyl alcohol (PVA) film, which produced a light-coloured nanocomposite film with high UV-shielding ability and enhanced tensile properties: the absorption of UV at wavelength of 400 nm and transparency in the visible-light region at wavelength of 550 nm was 116 times and 70% higher than that of pure PVA, respectively. In addition to these advantages, the nanocomposite film showed a water vapour transmission property comparable with commercial food package film, indicating potential applications.

Polyvinyl alcohol -nanocomposite films incorporated with clay nanoparticles and lipopeptides as active food wraps against food spoilage microbes

In the study, the effectiveness of lipopeptide containing nanocomposite film has been investigated for food packaging applications against the spoilage organisms and foodborne pathogens. Here, polyvinyl alcohol (PVOH) films incorporated with clay nanoparticles (C) and lipopeptides (L) were prepared by solvent casting. The prepared films were further characterized by Fourier transform-infrared spectroscopy, universal testing machine, and scanning electron microscopy. From the results, the lipopeptides and clay nanoparticles incorporated PVOH nanocomposite film (PNF) was found to have enhanced mechanical and barrier properties when compared with the neat PVOH film. The thickness, tensile strength, Young’s modulus, elongation at break, and water absorption capacity of the PNF film were 0.170 ± 0.008 mm, 34.4 ± 1.8 MPa, 1.4 ± 0.3 GPa, 82 ± 2 %, and 94.92 %, respectively. The PNF film developed in the study was found to inhibit the growth of foodborne pathogen Salmonella typhimurium and also the spoilage causing Pythium myriotylum. From the results, the films engineered with the lipopeptides and clay nanoparticles can be considered to have application as active food packaging wraps for the protection and preservation of food products.

Preparation and characterization of graphene oxide and cellulose nanofibers/ polyvinyl alcohol nanocomposite film

Polyvinyl alcohol (PVA) is well-known in the packaging industry, especially in the food and medical fields with the ability to be completely biodegradable and easily soluble in cold water therefore products made from it are the environmentally friendly materials. However, the disadvantages of this polymer as quick dissolubility in water, poor moisture retention, weak mechanical properties reduce its applications. In this study, PVA, reinforced by “green” components at the nanometer-level such as nanocellulose fibers (CNF), graphene oxide (GO) nanosheets showed improvements in properties. Mechanical properties of all of nanocomposite films showed improvements in stress at break and modulus. Especially, reinforced GO and CNF films increased almost doubled and improved more 40% in modulus than the pure PVA film and films reinforced by only GO or CNF. When immersed in water (neutral pH) at room temperature, graphene oxide-reinforced films not only had effective improvements in swelling time but also supported to decrease water retension of film added CNF. The combined reinforcement also indicated a benefit in reducing the rate of water vapor loss of the film as well as the efficiency in declining the moisture absorption of the nanocomposite films. The PVA films reinforced by nanocellulose fibers and graphene oxide sheets overcomed some of the PVA's shortcomings. This helped expanding its applications in the field of environmentally friendly nanocomposite films.

Fabrication of Reduced Graphene Oxide‐Silver/Polyvinyl Alcohol Nanocomposite Film for Reduction of 4‐Nitrophenol and Methyl Orange Dye

AbstractThe development of ingenious technologies for the purification of wastewater containing highly toxic organic compounds is of high importance in the current research. The application of noble metal nanocatalysts in the presence of sodium borohydride (NaBH4) for the removal of these toxic compounds through chemical reduction method have become an accepted approach in the recent years. The present work reports on the development of a convenient approach to fabricate free standing, robust, and flexible reduced graphene oxide ‐ silver/polyvinyl alcohol (rGO−Ag/PVA) nanocomposite film. The morphological and structural characterizations of the as developed film have been carried out using SEM, TEM, EDAX, Raman, BET, and TGA. The performance of as developed rGO−Ag/PVA nanocomposite film is tested as heterogeneous catalyst in the reduction reaction of 4‐Nitrophenol and reduction of Methyl Orange dye. The nanocomposite film‐based catalyst exhibited excellent catalytic performances as well as excellent stability in the reduction of toxic organic compounds in wastewater.

Highly transparent PVA/nanolignin composite films with excellent UV shielding, antibacterial and antioxidant performance

In the present work, polyvinyl alcohol (PVA) nanocomposite films containing various contents of lignin nanoparticles (LNP) (1, 2 and 3 wt%) were formulated by a simple solvent cast method and cross-linked by adding glutaraldehyde (GA) and citric acid (CA). Herein, we investigated the effects of crosslinker types and LNP loading on optical, thermal, mechanical, antioxidant and antibacterial behaviour of PVA nanocomposite films for active food packaging. The results of UV irradiation shielding effect showed that the addition of 3 wt% of LNP reduced significantly the UV-B/UV-C transmittance to 0 for both P-GA-3LNP (PVA film with 3 wt% of LNP cross-linked by GA) and P-CA-3LNP (PVA film with 3 wt% of LNP cross-linked by CA) films. Results of thermogravimetric analysis (TGA) showed that thermal stability for all PVA nanocomposites was improved, ascribing it to the strong interactions between LNP and PVA in presence of GA and CA. In the meanwhile, plasticization was also observed for both GA and CA crosslinked PVA films, with tensile strength increased from 26.0 MPa (PVA) to 38.1 MPa (P-GA-3LNP) and 32.7 MPa (P-CA-3LNP) and constant values of elongation at break (240, 229 and 237%) for these three films. Additionally, P-GA-3LNP film showed more evident antibacterial and antioxidant ability than P-CA-3LNP, with evidence of better maintained freshness of shrimps under UV irradiation fluorescence measurements.

Optical and Structural Properties of Biosynthesized Silver Nanoparticle Encapsulated PVA (Ag–PVA) Films

Silver (Ag) nanoparticles were successfully synthesized under ambient temperature employing Leucas Aspera (LA) leaves. The synthesis of silver nanoparticles at first confirmed by noting variations in the colour and subsequently morphological characteristics of prepared LA–Ag nanoparticles have been explored by using HR-TEM, and the particle size was found to be 3.67 nm which is in good agreement with XRD. SAED pattern represent the polycrystalline nature of Ag and crystallographic planes are close agreement with XRD. Implementing Diffraction Light Scattering (DLS) the average size is estimated to be 7 nm and the polydispersity index (PDI) was noticed to be 0.209 evince the uniform distribution. The same synthesised nanoparticles (NPs) were encapsulated further within a matrix of polyvinyl alcohol (PVA). Moreover, prepared nanocomposite films were characterised and correlated with both PVA-Ag matrix and pure PVA. To examine the optical characteristics of both LA–Ag-NPs and pristine PVA films were characterised via UV–Visible spectra. The influence of doping PVA with LA–Ag-NPs was being explored, i.e., structural, and morphological improvements including optical band gap, absorption coefficient, refractive index as well as optical conductivity. Besides, Fourier Infrared Spectroscopy benefitted to classify the alterations in the functional group. Scanning electron microscope visuals of synthesized nanoparticles reveal spherical shape in a polymer matrix, although the outcomes of energy dispersion findings support the appearance of silver. The structural parameters were determined by the use of X-ray diffraction studies, reflecting the d-spacing values and the crystalline nature with doping silver nanoparticle in PVA. This article addresses the research on structural and optical properties of LA–Ag–PVA nanocomposite films.

Polyvinylalcohol (PVA)-Assisted Exfoliation of ReS2 Nanosheets and the Use of ReS2-PVA Composites for Transparent Memristive Photosynapse Devices.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted significant attention for their outstanding optoelectrical properties. Unlike most TMDs with layer-dependent photoresponsivity, rhenium disulfide (ReS2) shows excellent thickness-independent photoresponsivity. Herein, we show a surfactant-free polyvinyl alcohol (PVA)-assisted exfoliation method for 2D-TMDs in aqueous solution and a transparent photosensitive memristor synapse device based on ReS2 nanosheets composited with PVA. ReS2 nanosheets are obtained via PVA-assisted exfoliation. After exfoliation, the ReS2-PVA dispersion solution is spin-coated on a substrate and dried to form a nanocomposite film without additional processing. Transparent memristors are then fabricated on plastic or glass substrates to demonstrate the applicability of the ReS2-PVA film. The devices show "write once, read many" memory behavior with a high ON/OFF current ratio (1.0 × 104 at 0.5 V) during electrical operation. In the high resistive state, synaptic functions with long-term memory behavior are successfully mimicked by applying photonic stimuli to the transparent ReS2-PVA memristors. The excitatory postsynaptic current stimulated by the photosignal is gradually reduced by electric stimuli. The proposed PVA-assisted exfoliation method is cost-effective, environmentally friendly, and applicable to various TMD nanomaterials. Furthermore, the ReS2-PVA nanocomposite film obtained via a simple solution-based process demonstrates excellent photosynaptic behavior.