PVA Composite Films Research Articles

High transmittance, high haze, and UV-harvesting CNNs@CNF/PVA composite film for light management

High transmittance, high haze, and UV-harvesting CNNs@CNF/PVA composite film for light management

Enhancing PVA mulching films: Leveraging modified lignin as a bio-based crosslinking agent for improved mechanical strength, UV barrier, and biodegradability

In contemporary agriculture, eco-friendly mulching films present a promising alternative to conventional plastic mulching films. However, their potential is constrained by challenges related to limited biodegradation and barrier performance. Addressing these limitations, innovative lignin-carboxylated materials were employed as bio-based crosslinking agents to enhance diverse properties in the fabrication of PVA films. Alkali lignin was modified with diethylenetriaminepentaacetic acid (DTPA) to enhance its chemical reactivity. The abundance of carbonyl groups in modified lignin (Lig-DTPA) plays a significant role in establishing strong compatibility with PVA through covalent bonds. This interaction yielded remarkable enhancements, elevating both tensile strength and tensile modulus by an impressive 50.9 % and 60.1 %, respectively. The introduction of Lig-DTPA at 3 % into the PVA composite films resulted in excellent UV-blocking properties. Moreover, at 3 % ratios, the presence of lignin became visibly dispersed as clear spots across the film, indicating a relatively uniform state within the matrix. The study revealed a direct correlation: as the lignin content increased, the film exhibited heightened water solubility and enhanced biodegradability. The PVA/Lig-DTPA film displays promising potential for utilization as a mulching film material, offering anti-ultraviolet functionality and a high degradation rate. Furthermore, its versatility extends to potential applications in packaging materials, including seedling bowls, transplanting pots, and coating films for transportation purposes.

Preparation of Coir Cellulose Nanofibers by Peroxyformic Acid Method and Their Application in Reinforced PVA Composite Films.

To increase the value of waste coconut shells and further broaden their use by biorefining, a milder and greener method to prepare cellulose nanofibers (CCNFs) was developed. The CCNFs were separated from coir fibers by using peroxyformic acid and alkali treatment in combination with high-power ultrasonication. The basic properties of the CCNFs were comprehensively evaluated using scanning and transmission electron microscopy, spectroscopy, diffraction, and thermogravimetric techniques. The results revealed that the developed preparation method provided CCNFs with typical nanocellulose sizes, structures, and properties. Nanocellulose-reinforced poly(vinyl acetate) (PVA) composite films were prepared using the CCNFs, and their mechanical properties, transmittance, crystallinity, and thermal stability were investigated. The elongation at break of the film with 8% CCNFs was 612%. The tensile strength of the films with 4 and 12% CCNFs was 41.3 MPa, which was higher than that of a PVA film (36 MPa). The transmittance and thermal stability of the PVA composite films were not appreciably affected by the CCNFs. The CCNFs show promise as a nanofiller for PVA-based composite films with favorable mechanical properties, crystallinity, and high transparency.

Development of biocompatible packaging material: starch/PVA-based bio-composite enhanced with hydroxypropyl methylcellulose

ABSTRACT Hydroxypropyl methylcellulose (HPMC) incorporated bio-composite films (unplasticized and plasticized) were prepared from pregelatinized maize starch/polyvinyl alcohol (PMS/PVA) blends by solution casting method. 10% boric acid (BA) was used as crosslinker. The physico-mechanical properties (tensile strength (TS), elongation at break (%EB), water solubility and moisture uptake) of the bio-composite films were studied. The thermo-chemical stability of the biofilms was studied by FT-IR, TGA and DSC analysis. TS, %EB, water solubility and moisture absorbency of 10% HPMC containing unplasticized films were found 38.1 MPa, 8.5%, 61% and 32.3%, respectively, however, the films were hard and brittle. On the contrary, TS, %EB, water solubility and moisture absorbency of 10% HPMC plasticized films were found 19.2 MPa, 28.5%, 62.2% and 57.3%. The biofilms exhibited relatively low water solubility and moisture uptake compared to higher HPMC containing composite. The thermo-chemical analysis revealed that the HPMC incorporated plasticized film was more thermally stable compared to pure PMS, PVA, HPMC and other bio composite films due to strong hydrogen bonding interaction with BA. The biodegradability of HPMC incorporated plasticized films was confirmed by soil burial test (anaerobic condition, RH 98%, 3 months). Therefore, the plasticized biofilm would be considered an alternative approach for biocompatible packaging material.

Complex Impedance Study of Graphite Nanopowder (GNP) Reinforced Polyvinyl Alcohol (PVA)‐Bismuth Ferrite (BiFeO3) Composite Films

AbstractIn this work, the graphite nanopowder (GNP) reinforced poly(vinyl alcohol) based Bismuth ferrite (BiFeO3; BFO) composite films with different weight percentages of GNP using a solution casting technique. The electrical properties of GNP‐reinforced PVA composites are investigated using a complex impedance spectroscopy (CIS) technique to show the bulk and grain effect with the rise in frequency by an impedance analyzer in a frequency range from 102 to 106 Hz at room temperature. The single semicircle is showing in the complex planes using the real and imaginary impedance characteristics. The GNP‐reinforced PVA composite films show evidence of bulk and grain impact in complicated impedance analysis. Based on the Nyquist plot, it appeared that only the bulk effects of the resultant composite systems are present.

Enhanced performance triboelectric nanogenerator based on mullite/PVA composites for self-driven sensing and smart home control

Polyvinyl alcohol (PVA) has good biocompatibility, a simple fabrication process, and environmental protection, which is very suitable for the production of triboelectric nanogenerator (TENG) applied to smart home control. However, the output performance of the TENG composed of PVA and PDMS films is not high. Previous research has explored the enhancement of PVA-based TENG performance by doping with conductive materials to modify the dielectric properties of PVA composite films. Nevertheless, this approach is associated with issues of high production costs and energy consumption. This work prepared a mullite/PVA composite material TENG (MP-TENG), the introduction of mullite induced interfacial polarization in the composite film. This effect resulted in the appearance of polarization centers, thereby enhancing the charge-sensing capability of the composite film. Consequently, the triboelectric output performance of the MP-TENG was improved. MP-TENGs with different amounts of mullite fiber doping were prepared, and the maximum output performance was obtained when the doping level reached 3 wt%. At this concentration, the composite film exhibited an open-circuit voltage of 70.89 V and a short-circuit current of 2.45 μA. An enhancement of 1.78 and 1.71 times was achieved with respect to the pure PVA-TENG, respectively. In addition, MP-TENG exhibited excellent sensing characteristics, a smart home control system was designed in conjunction with a hardware circuit, which captured hand motions and encoded them to generate binary codes to control the on/off state of the indoor home.

Pre-gelatinized high-amylose starch enables easy preparation of flexible and antimicrobial composite films for fresh fruit preservation

While high-amylose starch (HAS) possesses advantageous properties such as high resistant starch content and favorable mechanical attributes, its gelatinization constraints have limited its applicability. This study enhances its versatility by focusing on pre-gelatinized (PG) HAS with exceptional rehydratability, achieved by disorganizing native HAS granules (with amylose contents of 55 % and 68 %, respectively) using a 33 % CaCl2 solution, followed by water-ethanol precipitation and freeze-drying. The resulting PG-HAS exhibited elevated amylose content (61 % and 75 %) with minimal changes in amylose molecular weight. PG-HAS displayed superior water-absorption index (WAI) and water-soluble index (WSI) compared to native HAS, further improved by 2 % CaCl2 solution incorporation. Furthermore, composite films were prepared by mixing PG-HAS with PVA at a 6:4 (w/w) ratio. The PG-G50 (61 % amylose content)/PVA composite film exhibited remarkable elongation (131.1 ± 5.4 %), nearly three times that of a normal corn starch (NCS, with 27 % amylose)/PVA film, attributed to improved starch dispersity and higher amylose content. Nonetheless, the PG-G70 (75 % amylose content)/PVA film at the same ratio showed lower elongation (54.7 ± 8.0 %), potentially due to strong cohesive forces between amylose chains that impede starch-PVA interactions. Moreover, the PG-HAS/PVA composite films, enriched with antibacterial agents, demonstrated effective antibacterial properties with a gradual and sustained release of active compounds. Notably, the PG-G50/PVA/tannic acid (TA) film effectively preserved fresh apple slices by inhibiting bacteria growth and preventing browning. These findings underscore the excellent rehydration of PG-HAS and its potential as an inner packaging material for irregularly shaped foods, such as sliced fruits or meats, due to its nontoxic nature, softness and flexibility, which allows the film to maintain close contact with food surfaces.

One‐step Fabrication of Nitrogen‐Doped Carbon Dots‐Based Fluorescent Sensors with Red Emission for Efficient Detection of pH

AbstractCarbon dots have been widely noticed due to their excellent optical properties, such as good photostability and a wide excitation wavelength range. However, the emission peaks of most known carbon dots (CDs) are in the blue region, which hinders their extensive applications in long‐wavelength emission. In this study, red‐emitting carbon dots (RCDs) that are pH‐responsive are synthesized using citric acid and urea as precursors, and their fluorescence intensity increased gradually with increasing solution pH from 1 to 12. A new mechanism based on H aggregation and Fermi energy level transfer is proposed to explain the pH‐responsive emission of RCDs. In contrast to the narrow response range of most pH‐sensitive CDs reported so far, the pH‐responsive range of RCDs is large, especially in the alkaline range, and their pronounced red light emission is well visualized. The prepared carbon dots have the advantages of non‐toxicity, low cost, and a wide pH response range. In addition, “rose” test paper and carbon dot PVA composite film, RCDs‐PVA film, are made to demonstrate the visualization of carbon dots in pH detection. The “rose” test paper and carbon dot PVA still have good fluorescence intensity. The prepared carbon dots have good application prospects for pH detection.

Highly thermal conductive and flame retardant poly(vinyl alcohol) film with synergistic alignments of boron nitride nanosheets/Ti3C2Tx MXene for thermal interface materials

With the development of microelectronics and flexible wearable electronic devices, poly(vinyl alcohol) (PVA) based thermal interface materials (TIMs) have received much attention. However, poor heat dissipation and high flammability have emerged as the key issues that restrict their application. In this work, the directional alignment of phytic acid (PA) modified boron nitride nanosheets (BNNS) and Ti3C2Tx MXene in PVA matrix was achieved by ice-templated assembly, which simultaneously enhanced the flame retardancy and thermal conductivity of PVA composite films (PVA/BTx). Owing to the synergistic effect between oriented BNNS and Ti3C2Tx MXene on forming the thermally conductive network within PVA matrix, the in-plane thermal conductivity of PVA/BTx-30 composite film was increased to 8.54 W m−1 K−1, much higher than that of PVA film (0.30 W m−1 K−1). Meanwhile, the heat dissipation process of PVA films applied as TIMs was simulated, which showed that PVA/BTx-30 films exhibited excellent thermal conduction and significantly decreased the operation temperature of electronic devices. Additionally, the peak heat release rate (PHRR) and total heat release (THR) of PVA/BTx-30 films were reduced by 60.3% and 62.0%, respectively, showing good flame retardancy. Importantly, the flexible Ti3C2Tx nanosheets further enhanced the mechanical properties of PVA/BTx composite films. Therefore, this work provides an effective method for the preparation of high thermal conductivity and flame retardant composite materials, which has important potential applications in the microelectronics industry.

Dual function of new Nd(III) and Gd(III) complexes for cytotoxic and optoelectronic fields: Synthesis, characterization, DFT calculations, and PVA composite films

New two lanthanide complexes of Neodymium (III) and Gadolinium (III) ions were prepared based on 2‐Cyano‐N′‐([4‐oxo‐4H‐chromen‐3‐yl]methylene) acetohydrazide as a chelating agent. The prepared Nd(III) and Gd(III) complexes were characterized via elemental analysis, molecular conductance, IR, and TGA. The obtained results showed the chelating agent behaves as tridentate via oxygen of γ pyrone and carbonyl groups and nitrogen of the azomethine group. The antitumor activity of isolated complexes was investigated against the Ehrlich Ascites Carcinoma cell line (E.A.C). The results of antitumor activity cleared that Gd(III) complex has higher activity than Nd(III) complex and moderate activity relative to cisplatin and 5‐Furacil. Besides, DFT calculations were estimated for prepared Nd(III) and Gd(III) complexes by the Gaussian program. Theoretical parameters were calculated. The energy gap values confirmed the higher activity of the Gd(III) complex over the other Nd(III) complex. In addition, the composite films of Nd(III) and Gd(III) complexes were prepared using the cast technique. The electrical and optical absorption properties of these polymer composites were analyzed.

Q-Switched Erbium-Doped Fiber Laser Generation using Titanium Aluminum Carbonitride Ti3Al(C0.5N0.5)2 Saturable Absorber

A new MAX-phase-based saturable absorber (SA) known as Titanium Aluminium Carbonitride, Ti3Al(C0.5N0.5)2 PVA composite film is successfully developed to demonstrate a reliable Q-switched laser in the 1.55-micron region. The Ti3Al(C0.5N0.5)2 composite film with a size of about 1 mm2 is sandwiched between two fibre ferules and integrated into an erbium-doped fibre laser (EDFL) ring cavity. The film SA has a linear absorption of about 5.7 dB at the pulsing region, and a modulation depth of 21%. The Q-switched laser, which is centred at 1561 nm, stably appears at a pump power range of 25 mW-55 mW. The Q-switched laser has the highest repetition rate of 46.3 kHz and the narrowest pulse width of 6.6 µs. The maximum calculated peak power is 1.6 mW, while the highest pulse energy is 10.54 nJ. This demonstration suggests that the Ti3Al(C0.5N0.5)2 can be an alternative SA that may have a good prospect in optical-related applications.

Preparation and characterization of acid green 50 dye–PVA composite films and their optical power limiting characteristics

Preparation and characterization of acid green 50 dye–PVA composite films and their optical power limiting characteristics

Structural, conductivity and dielectric studies of pure and KCL doped polymer electrolyte films

Using the solution cast method, poly (vinyl alcohol) complexed with KCl was used to make solid polymer electrolyte films. XRD was used to look at the structure of these films. The outcomes of the Powder × - ray diffraction show that the composite films had more noncrystalline phases of PVA matrix. An AC impedance spectroscopy suggested that the ionic conductivity mainly arisen from grain effect. Conductivity of pure PVA is found to be of the order of 10-8 S/cm. With the addition of 20 wt% of KCl, the conductivity is dropped to the order of 10-10 S/cm, and then increased with the addition of KCl. The increase in conductivity with dopant type is based on the ionic character of the dopant. Real part of Impedance (Z') and imaginary part of impedance (Z“) of pure PVA and various composite films with 20 wt% of KCl, additives with different weight ratios were measured as a function of frequency. Dielectric permittivity and dielectric loss of all PVA with KCl 20 wt% of Polymer films investigated as a function of frequency at a room temperature is studied.Different electrochemical applications can be developed using these kinds of solid electrolytes.

Quasi-isotropic thermal conductivity of polymer films enhanced by binder-free boron nitride spheres

Heat dissipation has become increasingly crucial in miniaturized modern electronics. Thanks to the high in-plane thermal conductivity yet excellent electrical insulation, hexagonal boron nitride (h-BN) has been considered as an ideal filler material to enhance the thermal conductivity of polymers for efficient heat dissipation. However, the low out-of-plane thermal conductivity significantly limits their practical applications and a heat spreader that propagates heat along multiple directions is favorable. In this work, micro-sized, binder-free boron nitride spheres (BNSs) have been successfully synthesized using a two-step process of spray drying and high-temperature sintering. Consisting of randomly dispersed boron nitride nanosheets (BNNSs), the BNSs show an isotropic thermal conductivity of 34.8 W/mK. Using the BNSs as fillers, the out-of-plane thermal conductivity of poly(vinyl alcohol) (PVA) film is significantly enhanced to 8.1 W/mK, the second highest value compared with previously reported BN based PVA composite films. In the meantime, the in-plane thermal conductivity, up to 10.6 W/mK, is not sacrificed, indicating the quasi-isotropy in thermal conductivity. The significant thermal conductivity enhancement (∼3700%) of PVA is attributed to the formation of isotropic thermally conductive networks within the polymer matrix and strong interactions between BNNSs inside BNSs. This study provides a practical route to fabricate BN-enhanced composite films with isotropic thermal conductivity and promising materials that are valuable for heat dissipation in new-era advanced electronics and related applications.

Photophysical and electronic properties of Congo red dye embedded in polyvinyl alcohol as an efficient laser optical limiter: enhancement of the electrical conductivity and dielectric properties

High-quality polymeric composite films containing Congo red dye and PVA were prepared using the casting technique. The proposed Cr-doped PVA composites were examined using XRD, UV–visible optical, dielectric, and optical limiting effect techniques. The XRD patterns of CR-doped PVA composite films display diffraction peaks belonging to CR organic dye. There was a broadening and reduction of the initial peak intensity in polymer composite films at higher doping concentrations. The band edge of CR: PVA composites reduced with a massive shift from 4.63 to 1.86 eV, where Congo red controls the energy bandgap of the PVA polymer. Dielectric permittivity diminishes with increasing the frequency and achieves constant values at higher frequencies through the relation between the electric dipole and the electric field differences. Increasing the percentage ratio of the CR doping enhances the electrical conductivity and dielectric permittivities due to the large size of the CR molecules. The solid optical limiting of the CR-doped PVA composites is determined using different laser sources of 632.8 and 532 nm wavelengths. The excellent obtained results imply that CR: PVA composite films are very significant for applying large-scale CUT-OFF laser filters for medical optical and electronic device systems.

Genipin cross-linked chitosan–PVA composite films: An investigation on the impact of cross-linking on accelerating wound healing

The applications of composite films in wound healing are immense, and the quest for suitable biomaterials drives research. Natural polymers lack mechanical strength; by cross-linking, their chemical nature can be changed through interlinking via intermolecular interactions rather than chemical bonds. This study explores the applications of cross-linked chitosan–polyvinyl alcohol–genipin films prepared using the solvent casting method. The cross-linked films were analyzed for their chemical structural changes, structural morphology, mechanical strength, and water retention capabilities. Comparative studies were performed with the un-crosslinked counterparts. Results indicated an increased tensile strength of 67.2% and improved water retention because of their compact structure. Further, Fourier-transform infrared spectroscopy confirmed that cross-linking occurred in the films, and scanning electron microscope micrographs showed that the films were uniform with a continuous morphology. Thereafter, an in vivo study was performed to assess the effectiveness of the films on wounds made on Albino Wistar rats. Histopathological analysis indicated quick fibroblast generation and angiogenesis using the cross-linked films, affirming their suitability for wound healing applications.

UV-shielding and strong poly(vinyl alcohol) composite films reinforced with zinc oxide@polydopamine core-shell nanoparticles

Zinc oxide@polydopamine (ZnO@PDA) core-shell nanoparticles (NPs) were prepared by depositing PDA on the surface of ZnO NPs via the self-polymerization of dopamine (DA) in alkaline solution. It was found that ZnO@PDA exhibits lower photocatalytic activity and higher UV absorbance than pure ZnO. Moreover, ZnO@PDA NPs could be homogenously dispersed in poly(vinyl alcohol) (PVA) matrix and form strong hydrogen bonding interaction with PVA molecular chains. As a result, the prepared PVA/ZnO@PDA composite films display excellent UV-shielding, mechanical and anti-UV aging properties. Particularly, the PVA composite film added with 2.0 wt% ZnO@PDA is able to shield 96.1% UV irradiation (200–400 nm) and exhibits superior tensile strength (66.3 Mpa) than pure PVA film. Moreover, the result of UV aging tests indicate that ZnO@PDA also give a positive effect on the UV stability of PVA matrix, while PVA/ZnO composite film shows serious degradation. This work proposed a facile and rational strategy to design the ZnO-based UV-shielding agent with reduced photocatalytic activity and enhanced UV absorbance, which may provide an inspiration to construct high performance UV-shielding composites.

Synthesis of p-phenylenediamine treated fibrillated cellulose fiber and its application in poly(vinyl alcohol) composites

ABSTRACT This research aims to improve the strength and durability of poly(vinyl alcohol) (PVA)-based packaging film with modified fibrillated cellulose fiber (FCF). FCF was extracted from jute fiber by numerous physical and chemical treatments. It was then modified by p-phenylenediamine (pPD) with the catalytic support of FeSO4/K2S2O8. The extent of modification was detected by infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The crystalline index (CrI) was calculated from the X-ray diffractogram (XRD) data. The thermogravametric analysis (TGA) revealed that pPD-FCF exhibited the highest thermal resistance compare to raw jute fiber (RJF), alkali hydrolyzed fiber (AHF) and FCF. The PVA composite films were prepared with RJF, AHF, FCF and pPD-FCF by solvent casting method. The properties of pure PVA and its composites were evaluated for comparison. The pPD-FCF/PVA composite presented highest tensile strength and tensile modulus. The pPD-FCF/PVA composite showed lowest weight loss through soil burial test than other composites and pure PVA. By consideration of those commendable properties, the pPD-FCF/PVA composite material could promote the opportunity for packaging application.

Extracted Pomace Olive Oil Use for the Preparation of Starch Graft Copolymer

In this work, the relevant parameters of a pomace olive oil consecutive solvent extraction method using ethanol, and petroleum ether are investigated from dry and wet pomace samples. It is found that, oil extraction from dry samples with petroleum ether showed a high yield (11.72±0.30%) with solvent recovery of 89%, while extraction yield with ethanol is (11.1±0.60%) with solvent recovery of 90%. Moreover, it is found that the oil extraction from wet samples with ethanol is possible but the economic feasibility is not proven as the solvent recovery is of 62%. On the other hand, the possibility of hydrolysis of the crude extracted pomace oil in alkaline medium is demonstrated in this work. In this context, the starch grafting of the obtained long chain mono-fatty acids was accomplished in the presence of Fenton's reagent in a Dimethyl formamide (DMFA)/Water solution. Sonication is used for reaction mixture homogeny and the biopolymer was obtained using domestic microwave heating. After characterizing the obtained grafting polymer, it was employed to prepare a composite material with polyvinyl alcohol. The prepared PVA composite film of grafted starch (PVA/gSt) has tensile strength of (5.84 MPa) while its elongation modulus increased by 123.6%. Moreover, it was observed, in this work, that (PVA/gSt) copolymerization increases both the crystalline structure and the morphological order. This result is contrary to the available literature related to copolymerization of starch with different mono acids. It is found that, the consecutive solvent extraction method is of promising aspect from technical and economic point of view and the grafted starch compatibility with other polymers may be improved. The PVA/gSt films could be applied as packaging films.

Preparation of cellulose nanocrystals coated with polymer crystals and their application in composite films

AbstractIncreasing the dispersibility of cellulose nanocrystals (CNCs) as a reinforcing material is highly desirable to obtain composites with enhanced mechanical properties. To this aim, nanocomposite fibers (NCF(CNC/polymer)) were fabricated by coating CNCs with polymer crystals. Poly(vinyl alcohol) (PVA) and poly(vinyl alcohol‐co‐ethylene) (EVOH) were crystallized from a dilute solution in the presence of CNCs, which acted as nucleating agents for polymer crystal growth on the CNC surface. NCF consisting of CNCs coated with PVA crystals (NCF(CNC/PVA)) and CNCs coated with EVOH crystals (NCF(CNC/EVOH)) were successfully obtained. Both NCF(CNC/polymer) showed good dispersibility in water, even after drying, and were used to prepare composite films with improved mechanical properties. The reinforcement effect of NCF(CNC/PVA) was greater than that of pure CNCs and NCF(CNC/EVOH). The PVA composite films exhibited optical transmittance above 99% compared with additive‐free PVA films. No agglomerates appeared even under the optical microscopic observation of the PVA composite film, and NCF(CNC/PVA) dispersibility was extremely good. NCF(CNC/PVA)‐added PVA composite films exhibited increased glass transition temperature compared with additive‐free PVA films, and the crystallinity of the PVA film increased. The highly dispersed CNCs in the PVA matrix and the increase in the glass transition temperature and crystallinity caused an increase in the mechanical modulus of the PVA composite film at low NCF(CNC/PVA) content. Furthermore, the effect of the morphologies of cellulose nanofibers and CNCs on the mechanical properties of the composite films prepared using the respective NCFs was investigated.