Sodium Lignosulfonate Synergistically Modified LDHs Achieve Toughening and Enhanced Barrier Properties in PVA-Based Nanocomposite Films

Ultrahigh gas barrier poly (vinyl alcohol) nanocomposite film filled with congregated and oriented Fe3O4@GO sheets induced by magnetic-field

In this study, graphene oxide (GO) is synthesized by a modified Hummers method, Polyvinyl alcohol (PVA) films and PVA/ GO nanocomposite films are prepared by casting stable aqueous mixed solutions. X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) showed that there were a good compatibility and dispersion of graphene oxide (GO) on PVA matrix. In addition, nanocomposite films reinforced graphene oxide with the content of only 0.6 % phr have had 10.11% higher tensile strength, 12.24 % greater Young modulus, and significantly reduced water permeability during 4 hours of continuous immersion. Nanocomposite films maintained good thermal stability despite being added with graphene oxide, a material that is considered to have low thermal stability that easily decomposes below 200 oC, so thermal gravimetric analysis diagram (TGA) of PVA/ GO almost did not show a change compared to the neat PVA film. Initial results show that the efficiency of dispersing and reinforcing graphene oxide material on PVA resins has ameliorated the drawbacks of this polymer and contributed to extending the application of PVA in many areas. This has also reached closer to the goal of cleaning the environment by replacing non-biodegradable polymer sources with more friendly polymers.

In this research, titanium dioxide (TiO2) nanoparticles were immobilized into polyvinyl alcohol (PVA) matrix without and with surfactants via solution casting film combined with thermal treatment method. The dispersion and distribution of TiO2 nanoparticles presented by scanning electron microscopy (SEM) showed the uniform distribution of TiO2 nanoparticles in PVA matrix with surfactant. Fourier-transform infrared spectroscopy (FTIR) showed increasing intensity peak at 560-800 cm-1 corresponding to Ti-O stretching vibration indicating interaction between PVA and TiO2 after thermal treatment. X-ray diffraction (XRD) result showed peak of PVA crystal structure due to the thermal treatment, and the addition of surfactant could decrease the average crystallite size of TiO2 in PVA/TiO2 nanocomposite films. Photocatalytic activity was determined from the film efficiency on removal of methylene blue (MB) under ultraviolet (UV). The results showed the greater MB removal efficiency of the PVA/TiO2 nanocomposite films with surfactant and thermal treatment than those without surfactant and thermal treatment.

PurposeThis study aims to fabricate multiwalled carbon nanotubes (MWCNTs)-mediated polyvinyl alcohol (PVA) composite films using the solution casting approach.Design/methodology/approachThe prepared films were evaluated for diverse structural, surface, optical and electrical attributes using advanced analytical techniques, i.e. electron microscopy for surface morphology, Fourier transform infrared spectroscopy for tracing chemical functionalities, x-ray diffraction (XRD) for crystal patterns, water contact angle (WCA) analysis for surface wettability and UV visible spectroscopy for optical absorption parameters. The specimens were also investigated for certain rheological, mechanical and electrical properties, where applicable.FindingsThe surface morphology results expressed a better dispersion of MWCNTs in the resultant PVA-based nanocomposite film. The XRD analysis exhibited that the nanocomposite film was crystalline. The surface wettability analysis indicated that with the inclusion of MWCNTs, the WCA of the resultant nanocomposite film improved to 89.4° from 44° with the pristine PVA film. The MWCNTs (1.00%, w/w) incorporated PVA-based film exhibited a tensile strength of 54.0 MPa as compared to that of native PVA as 25.3 MPa film. There observed a decreased bandgap (from 5.25 to 5.14 eV) on incorporating the MWCNTs in the PVA-based nanocomposite film.Practical implicationsThe MWCNTs’ inclusion in the PVA matrix could enhance the AC conductivity of the resultant nanocomposite film. The prepared nanocomposite film might be useful in designing certain optoelectronic devices.Originality/valueThe results demonstrated the successful MWCNTs mediation in the PVA-based composite films expressed good intercalation of the precursors; this resulted in decreased bandgap, usually, desirable for optoelectronic applications.

In this work, metal/semiconductor nanocomposites/metal devices with aluminium (Al) as top electrode (TE) and bottom electrode (BE) were fabricated and investigated using ZnO nanoparticles (ZNPs) embedded in an insulating polyvinyl alcohol (PVA) matrix for non-volatile memory applications. The I-V measurements of Al/ZnO-PVA/Al device exhibited a non-volatile bistable resistive switching behaviour. The switching mechanism of the device was suggested by the models of trap controlled space-charge limited conduction (SCLC) and the charges trapping-detrapping process at the centers of ZNPs in the PVA matrix. The state of the device was maintained even after removal of the applied bias, indicating the non-volatile bistable memory. There was no remarkable degradation of the device in both the LRS and the HRS after 30 minutes continuous operation which demonstrated excellent stability of the device. The current ratio of high resistance state (HRS) to low resistance state (LRS) is about of the order of 102 at room temperature. This demonstration provides a class of memory devices for non-volatile bistable memory device applications.

Boron nitride nanosheets (BNNS)/polyvinyl (PVA) nanocomposite films with anisotropic thermal conductivities are fabricated by sequential unidirectional freeze casting (UFC). High in-plane TC is made possible by the interconnection and alignment of thermally conductive BNNS through segregating BNNS in between PVA matrix. The nanocomposite films also possess very low dielectric loss arising from the inherent electrically insulating characteristics of BNNS. The unique combination of properties make them a potential candidate for thermal management in integrated circuits and microelectronics. • Segregated and aligned BNNS in PVA matrix are achieved using sequential freeze-casting. • The sequential freeze-casting involves infiltrating BNNS into the microchannels of PVA aerogel followed by hot pressing. • The unique structure yields 267% higher thermal conductivity than conventional composites with dispersed BNNS. • The nanocomposite films possess high in-plane thermal conductivity, good electrical resistivity, and low dielectric loss. • These unique properties make the composite film an ideal candidate for heat dissipation in microelectronics. High interfacial thermal resistance (ITR) between thermally conductive nanofillers and polymer matrix, and lack of good orientation of nanofillers are primary limiting factors in harnessing their inherent thermal conductivity in polymer nanocomposites. Thus, exploiting ultrahigh thermal conductivities of nanofillers involves developing methods or mechanisms that can minimize the ITR. In this work, boron nitride nanosheets (BNNS)/polyvinyl alcohol (PVA) nanocomposite films with segregation-induced interconnection among BNNS are fabricated by a sequential unidirection freeze-casting (UFC) technique. A PVA aerogel is first made by UFC followed by infiltrating functionalized BNNS into its pores and microchannels which is subjected to a second UFC process. The composite aerogel is subsequently hot pressed to compact the available pore channels for reduced ITR arising from better contact between the segregated BNNS cell walls. The resulting segregated BNNS/PVA (SBP) nanocomposite film with 40 wt% BNNS exhibits high thermal conductivity of 5.2 W/mK, which is about 267 % higher than the nanocomposite film containing dispersed BNNS made by conventional UFC. The SBP film also possessed high electrical insulation characteristics and a very low dielectric loss of 10 - 2 at a frequency of 1 kHz, properties arising directly from the segregated BNNS. The sequential UFC provides an effective method to incorporate aligned and interconnected BNNS through segregation for enhanced thermal conductivity and electrical resistivity for thermal management in microelectronics and integrated circuits.

Polymer inorganic nanocomposites are attracting a considerable amount of interest due to their enhanced electrical and optical properties. The inclusion of inorganic nanoparticles into the polymer matrix results in a significant change in the nanocomposite’s properties. With this in mind, we have developed a nanocomposite film based on zinc oxide (ZnO) and polyvinyl alcohol (PVA) using a solution casting method with varying concentrations of ZnO nano powder in the PVA matrix. The ZnO / PVA film surface morphology was observed by the scanning electron microscope (SEM). The micrographs indicate that ZnO nanoparticles in the PVA matrix are homogeneously distributed. XRD results indicated that the crystallinity of the film was influenced by the interaction of ZnO nanoparticles and the PVA main chain. Crystallinity is also affected by the doping of ZnO nanoparticles in the PVA matrix and it increases when the concentration of ZnO is low and then decreases when the excess concentration of ZnO is present in the PVA matrix. The FTIR transmission spectra confirmed that significant interaction took place between the ZnO nanoparticles and the PVA main chain over the wave number range of 400–4000 cm−1. The UV–vis spectra reveal that the increase in concentration of ZnO nanoparticles in the polymer matrix results in the movement of the absorption edge in the direction of higher wavelength or lower energy associated with the blue/green portion of the visible spectrum. A decrease in the optical energy bandgap is observed with the increase in nano ZnO concentration in the matrix. Thickness has a signifcant affect on the properties of the ZnO/PVA nanocomposite and the morphology, particle size, degree of crystallinity and bandgap of the ZnO/PVA nanocomposite samples were influenced by the thickness of the sample. The optimal thickess of 0.03 mm with a weight percentage of 16.6% (ZnO) and 83.3% (PVA matrix) was selected due to its higher bandgap of 4.22 eV, reduced agglomeration/aggregation and smaller ZnO particle size of 14.23 nm in the matrix. The optimal film can be used in photovoltaic research.

ENHANCEMENT OF GIANT MAGNETORESISTANCE IN Fe 2 O 3 -MWCNT/PVA NAN o COMPOSITE FILM . Synthesis and magnetic properties characterization of Fe 2 O 3 -MWCNT/PVA nano Composite film were carried out. Fe 2 O 3 -MWCNT as a filler of nano Composite thin film were synthesized using simple mixing methods froma solution containing FeCl 3 , and Multi-Walled Carbon Nanotube (MWNT). The solution was sonicated for almost 20 minutes then dried at 450 o C for one hour. The mixture of the two composition was dispersed with Sodium Dodecyl Sulfate (SDS) in 20 mL aquabidest and homogenized by ultrasonicator for 15 minutes at 40 o C. Then filler was then mixed with Polyvinyl Alcohol (PVA) with some various concentration and dried overnight at room temperature. X-Ray Diffraction (XRD) analysis and Raman Spectroscopy were used to find out the presence of Fe 2 O 3 phase in as prepared sample. Iron oxide phase partially filled in the wall of MWCNT observed by Transmission Electron Microscope (TEM). The Giant Magnetoresistance (GMR) properties were investigated. The maximum GMR value was negative 80% of the composition 1:9 filler/matrix volume ratio. The linear negative of the magnetoresistance (MR) ratio is coincident with a model as proposed by Nguyen, Spivak and Shklovskii (NSS) and related to the effect of quantum interference between Fe 2 O 3 -MWCNT in PVA matrix.

The orientation of biopolymer macromolecules and nanoclay, specifically Montmorillonite (MMT) nanoplatelets, plays a crucial role in controlling the properties of multi-layer film structures. Understanding the impact of macromolecule and nanoclay platelets’ orientation on barrier properties of packaging films is essential. To investigate the influence of hydrogen bonding in multilayer films structures, two polymers, namely polyvinyl alcohol (PVA) and chitosan (CS), were selected and laminated nanocomposite films were fabricated using the spin coating-assisted layer-by-layer (Spin-LbL) assembly technique. This technique facilitates the production of highly oriented nanocomposite films, where polymer chains and nanoclay particles align parallel to the film surface. Multi-directional 2-D wide-angle X-ray diffraction (2D-WADX) was successfully used to accurately assess the orientation and distribution of MMT nanoplatelets. Additionally, the films underwent characterization using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The 2D-WADX analysis revealed a parallel alignment of both the PVA chains and MMT clay nanoplatelets parallel to film surface. The XRD results confirmed the formation of intercalated nanolaminate structures, hydrogen-bonding interactions, and adjustments in the crystalline structure of PVA matrix. Through contact angle and oxygen permeability measurements, we observed that all quadri-layer film structures exhibited hydrophobic properties and reduced oxygen permeability compared to neat PVA films. Furthermore, the integration of MMT nanoclay, even at low concentrations, contributed to the development of nanocomposite films with improved oxygen barrier properties. Consequently, the quadri-layer films demonstrate great potential for food packaging applications.

Effect of CNT/CNC hybrid nanofiller on PVA/CNT/CNC nanocomposite

The study focuses on developing a noninvasive, flexible polyvinyl alcohol (PVA)‐nickel (Ni) nanocomposite thin film as a passive skin‐integrated patch sensor for wearable temperature monitoring, marking a significant advancement in the field of wearable sensors. This flexible PVA‐Ni nanocomposite thin film serves as a temperature‐sensitive material, offering several advantages over commercially available active‐type sensors. Field emission scanning electron microscopy (FE‐SEM) images show that Ni nanoparticles (NPs) are broadly dispersed throughout the PVA matrix, indicating the effectiveness of the conductive patch in detecting temperature variations. A PVA‐Ni nanocomposite patch with a thickness of 0.08 mm demonstrated superior flexibility, breathability, and lower tearing strength compared to a pure PVA patch. The film also exhibited excellent repeatability in bending tests, maintaining performance after 120 bending and unloading cycles, suggesting its durability for long‐term use as a wearable sensor. Furthermore, the fabricated sensors function as thermistors, with conductivity increasing linearly with temperature. The performance of these temperature sensors was compared, revealing a highest temperature coefficient of resistance (TCR) and thermal index of −1.08%/°C and 1271 K, respectively. The sensors showed high temperature sensitivity between room temperature and 50°C, outperforming typical commercial platinum temperature sensors. The stability and response time of the PVA‐Ni nanocomposite film were evaluated by adhering the patch to a human wrist and capturing thermal images using a FLIR thermal imaging camera. The observed maximum temperature difference of approximately 1.9–2.1°C highlights the patch's sensitivity in detecting temperature changes. Additionally, the antimicrobial properties of the conductive film were tested to assess its biocompatibility, confirming its potential for applications in energy storage, thermal management, and early breast cancer detection.

With an intention to replace the synthetic non-biodegradable films in packaging applications, the polyvinyl alcohol (PVA) blended with green banana peel filler (GBPF), the biodegradable films were prepared by solution casting method with varying the concentrations of GBPF (5–25 wt%) in PVA matrix. The bio films were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermo gravimetric analysis, transmissibility, FESEM, tensile test, film solubility and water absorption, water vapour transmission (WVT), soil burial test. Based on results obtained, the changes evidenced in the FTIR spectrum of this PVA/GBPF biofilms suggest that strong hydrogen bonding is taking place due to interfacial exchanges of GBPF in PVA matrix. The XRD results showed that crystallinity of bio films are greater than PVA. Thermo gravimetric analyses predicted that PVA/GBPF bio films are thermally stable up to 300 °C. The light is 45% for transmittance in the visible light region for the PVA/GBPF (25 wt%) bio film. The FESEM micrographs of biofilms palpable that formation of good physical interaction and compatibility between polymer matrix and GBPF up to 20 wt% of GBPF in PVA Matrix. FESEM results also confirmed that higher loading of GBPF (25 wt%) in PVA matrix, observed voids and agglomerations in film surface. The PVA/GBPF bio films with 20% of GBPF gave the highest tensile strength and young’s modulus 44.5 MPa and 66.7 GPA respectively compared to other samples. The elongation at break decreases with increases the GBPF in PVA Matrix up to 20 wt%.The slight decrease in mechanical properties perceived due to higher loading of GBPF (25 wt%) with PVA matrix. The solubility, water absorption and WVT of the PVA/GBPF bio films increased upon increasing the GBPF content. The biodegradation test results discovered that he highest weight loss at 42.3% (25 wt% of GBPF) probably due to the hydrophilic nature of GBPF in PVA matrix. On the whole, the present investigation confirmed that the PVA/GBPF bio films potential for possible utilization in active packaging applications attributable to its better mechanical, thermal, optical, water absorption and biodegradation properties.

In this research work, polyvinyl alcohol (PVA)-graphene (Gr) nano composite films were fabricated by incorporating the functionalized graphene (f-Gr) for different periods of refluxing and vacuum oven time. The graphene particles were functionalized through nitric acid (HNO3). Various tests were conducted to estimate the properties and characteristics of this composite. Fourier transform infrared spectroscopy (FTIR) results confirm the bonds of carboxyl, hydroxyl and carbonyl groups, manifested of functionalization of graphene. Scanning electron microscopy was performed to investigate morphology and transparency of f-Gr nano-particles in nano-composite films. Water absorption test was carried out to evaluate water absorption (%) in the PVA based composite films. The result revealed that water absorption rate of the composite decreased with increasing refluxing time at constant vacuum oven time of f-Gr reinforced composite. Dynamic mechanical analysis (DMA) showed that the value of storage modulus was higher for PVA-f-Gr nano-composite films compared to neat PVA and PVA-Gr composite over the entire range of temperature, which lead to explore this composite material for the vibration isolation applications. Glass transition state (Tg), loss modulus and the damping factor (tan δ) of the PVA-f-Gr nano composites films were highly affected by the addition f-Gr nano crystals in the PVA matrix. The value of tan δ for f-Gr nano composite is obtained both higher as well as lower compared to PVA-Gr film for the varying vacuum oven time and refluxing time. Electrical analysis indicates an enhancement in conductivity of PVA with introduction of f-Gr nano particles. After evaluating the high damping characteristics of this composite, the authors perceive that it may be utilized to reduce noise transmission and as a shock absorber vibration isolator.

Polyethylene (PE) film, despite its dominant market presence in food packaging, is fundamentally limited by inadequate oxygen barrier performance and absence of intrinsic antioxidant activity, leading to accelerated oxidative spoilage of packaged foods. To overcome these constraints, this study introduces an innovative coating strategy that functionalizes PE films with a composite layer of polyvinyl alcohol (PVA), silane‐modified layered double hydroxide (ALDH) and tannic acid (TA). The optimized film (PE‐PVA/ALDH/TA 10 ) demonstrates exceptional properties, achieving an ultra‐low oxygen transmission rate of 0.033 cm 3 m −2 day −1 atm −1 and a high 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radicals with a scavenging rate of 79.2%. Structural analysis confirms that ALDH and TA promote the formation of a dense hydrogen‐bonded network within the PVA matrix, which significantly reduces oxygen permeability while imparting strong antioxidant activity. Furthermore, the coated film retains high visible‐light transparency and exhibits exceptional UV‐blocking efficiency, reaching 97.3% in the UVC–UVB range. Preservation tests using bananas validate the material's effectiveness in delaying ripening, minimizing weight loss and maintaining fruit quality. This work presents a scalable, multifunctional packaging solution that combines ultra‐high barrier performance with antioxidant functionality for extended food preservation.

Background: Polymer-clay nanocomposite (PCN) materials have become a focus of research due to their unique characteristics and potential commercial applications. Clay addition in polymers improves their properties and may result in better features. PCN materials are reported to have enhanced thermal, mechanical, flame retardation, corrosion protection characteristics. Objectives: This study investigates the effect of different loading concentrations of Na-rich montmorillonite (MMT) clay when they are effectively dispersed in a organic polyvinyl alcohol (PVA) matrix. Methods: PCN materials were prepared using the solution method. The structure morphology of the PCN was studied using x-ray diffraction (XRD) and NSEM. FTIR was applied to study the molecular structure of the PCN. The mechanical properties of the pure PVA and PCN were studied. The thermal stability of the PCN was studied using TGA and differential scanning calorimetry (DSC). Results: The morphological images and crystalline morphology indicated that PVA and MMT clay has intercalated by the uniform and homogenous dispersion and confinement of the PVA polymer chains within silicate layers of the clay. PCN XRD pattern has a high d-spacing compared to the pure MMT clay XRD pattern, which has a low d-spacing (Fig. 1). FTIR showed that as the loading of MMT clay increases, the intensities of the MMT clay bands become stronger in the FTIR spectra of PCN (Fig. 2). NSEM results showed that intercalation that took place between the PVA and MMT. It was found that the small amount of MMT clay made the tensile modulus and elongation percentage the PCN significantly higher than the pure PVA, due to polymer-clay intercalation. Thermal stability results showed that the PCN is more thermally stable than pure PVA. Conclusions: The excellent MMT nanoclay dispersion in PVA matrix leads to significantly enhanced mechanical properties, notably an increase in tensile moduli with significant increase in tensile strength, maximum load and percentage elongation of the PVA due to adding the small amount of MMT clay. The uniform and homogenous dispersion of MMT in PVA matrix results in an increase in thermal decomposition temperature and glass transition temperature of the promoted PVA polymer based on TGA (Fig. 3) and DSC (Fig. 4) results.