Pure PVA Film Research Articles

Greatly improved thermal conductivity and electrical insulation for PVA composites via introducing functional carbon nitride nanosheets

Carbon nitride has captured much attention of researchers since it was discovered, while few studies have focused on exploring the thermal conduction applications. In this paper, carbon nitride nanosheets (CNNS) could be simultaneously functionalized during the process of exfoliation. FTIR tests proved that hydrogen bonds were constructed between PVA matrix and CNNS, at the same time, superior dispersion were also observed from SEM characterizations. In this case, significantly improved compatibility at the interfaces of them could be achieved without additional modifications. The maximum in-plane thermal conductivity of CNNS/PVA composites was enhanced to 2.7 W m−1 K−1 with low CNNS content (7.5 wt%), resulting in a sharp enhancement (785%) in comparison with that of pure PVA film (0.305 W m−1 K−1). More importantly, the as-prepared CNNS/PVA composite (at 7.5 wt% CNNS content) could even be comparable to traditional highly thermally conductive polymer composites (Graphene, Boron Nitride, Mxene, etc., were used as fillers) in terms of similar conditions. Meanwhile, the incorporation of 7.5 wt% CNNS PVA composites also showed excellent mechanical properties and electrical insulation, where the tensile strength, elongation at break, and volume resistivity reached up to 30.578 Mpa, 193.089%, 3.34 × 1011 Ω·cm respectively. These multifunctional features further indicate that CNNS/PVA composites possess the great potential for thermal management. Therefore, this work can provide effective references to prepare highly thermally conductive polymer composites by constructing in-situ functionalized CNNS, and expands its application as well.

Enhancing the Thermal and Mechanical Characteristics of Polyvinyl Alcohol (PVA)-Hemp Protein Particles (HPP) Composites

AbstractThis paper aims to describe the thermal, mechanical, and surface properties of a PVA/HPP blend whereby the film was prepared using a solution casting method. The improvements in thermal and mechanical properties of HPP-based PVA composites were investigated. The characterization of pure PVA and PVA composite films included tensile tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results of TGA and DSC indicated that the addition of HPP increased the thermal decomposition temperature of the composites. Mechanical properties are significantly improved in PVA/HPP composites. The thermal stability of the PVA composite increased with the increase of HPP filler content. The tensile strength increased from 15.74 ± 0.72 MPa to 27.54 ± 0.45 MPa and the Young’s modulus increased from 282.51 ± 20.56 MPa to 988.69 ± 42.64 MPa for the 12 wt% HPP doped sample. Dynamic mechanical analysis (DMA) revealed that at elevated temperatures, enhanced mechanical properties because of the presence of HPP was even more noticeable. Morphological observations displayed no signs of agglomeration of HPP fillers even in composites with high HPP loading.

Moderately Transparent Chitosan-PVA Blended Membrane for Strong Mechanical Stiffness and as a Robust Bio-Material Energy Harvester Through Contact-Separation Mode TENG

The detection of sustainable materials from naturally available resources using a simple fabrication process is highly important for novel research. Here, we used chitosan-PVA (Chs-PVA) blend films via layer-by-layer casting technologies for generating power through mechanical induction through triboelectric nanogenerators. The proposed Chs-PVA biodegradable film (i.e., thickness of 60 ± 5 μm) is facile, ecofriendly, highly flexible, mechanically strong, cost-effective, and easy to scale up. FT-IR analysis of the ChS-PVA blend membrane showed the strong interactions between the amines of ChS and hydroxyl groups of PVA through chemical cross-linking by hydrogen bonding. More importantly, the triboelectric nanogenerators (TENG) values of ChS-PVA films were 3–4 orders of magnitude lower than chitosan films reported before. Layer-on-layer cast films in particular exhibited high tensile strength (15.8 ± 1 MPa) and were more than three times stronger than other polyelectrolyte multilayer films. Both types of films remained stable in an acidic environment. Furthermore, the layer-on-layer-assembled films presented greater open circuit voltage (Voc) and short circuit current (Isc) values compared to pure ChS and PVA films. The ChS-PVA membrane can be used as a functional layer to produce charges by collecting get-up-and-go through vertical contact and separation mode TENG counters to the PVDF membrane. The enhancement of Voc and Isc of ChS-PVA TENG were 244 and 1,080% from ChS TENG. Where in the case of PVA TENG, the enhancement of Voc and Isc were increased by 633 and 2,888%, respectively due to the availability of free loan pair on the -NH2 and -OH functional groups. The novel ChS-PVA TENG is a potential candidate for satisfying the tight requirement of an optimized energy harvesting device as an alternate bio-material option for contact-separation mode TENGs.

Electrochemical Impedance Spectroscopy as a Novel Approach to Investigate the Influence of Metal Complexes on Electrical Properties of Poly(vinyl alcohol) (PVA) Composites

In the current study, black tea leaves extract solution (TES) as a new green technique is used to fabricate metal-polyphenols complexes (X-polyphenols complex; X= Cu+2, Ce+3, and Cd+2). The metal-complexes are integrated with poly (vinyl alcohol) (PVA) to prepare PVA composite films. The electrical properties of pure PVA and composites are characterized using the electrochemical impedance spectroscopy (EIS) method. The EIS data are fitted to the electrical equivalent circuit to evaluate the impedance parameters of pure PVA and composite films. The trend of DC conductivity is further verified by dielectric analysis. The electrical parameters are considerably improved upon incorporating with the metal-complexes. The effects of the metal-complexes on the modification of PVA are compared together. The PVA composite incorporated with the Cu+2-complex shows the highest DC conductivity and dielectric constant, which is important for application in electrochemical energy storage devices such as batteries and supercapacitors, in comparison with the Ce+3- and Cd+2- complexes.

Green coordination chemistry as a novel approach to fabricate polymer:Cd(II)-complex composites: Structural and optical properties

In the present work black tea leaves extract solution as a novel green coordination method was used to synthesis cadmium metal ions-complexes (Cd2+-polyphenol complex) with enhanced absorption in UV–vis region. The Cd2+-polyphenol complexes were mixed with poly (vinyl alcohol) (PVA) to fabricate composite films with tunable optical properties. The construction of direct band gap (DBG) polymer composites with developed amorphous phase is vital for applications in optoelectronic devices. The Cd2+-polyphenol complexes and composite films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV–Vis spectroscopy. The outcomes indicate that the interaction between Cd+2 ions and polyphenols can create Cd2+-polyphenol complex. It is displayed by the XRD findings that the synthesized Cd2+-polyphenol complexes are amorphous structure. The analysis of XRD deconvolution shows a development of amorphous nature of PVA with Cd2+-polyphenol complex insertion. The FTIR results exhibit the occurrence of complexation between PVA and Cd2+-polyphenol complex. From UV–Vis spectroscopy study, the optical parameters (absorption edge, refractive index (n), dielectric constant (εr), dielectric loss (εi), and band gap energy (Eg)) of pure PVA and composite films were measured. Examination of the εi optical parameter is carried out in order to measure the Eg, while kinds of electronic transition in the films are determined based on the Tauc's method.

A Study of the Effect of Starch Content on the Water Absorption of PVA/starch Blends

The present work aims to study physical tests such as the water absorption tests of PVA; PVA/corn starch blends at different mass percent (25, 30, 35, 40, and 50%) of corn starch after immersion in distilled water for ten minutes. The blends were also characterized by FTIR analysis, and an optical microscope. Casting method used to prepare samples. The results of water absorption exhibited that the weight losses of the sample increases the starch content rises in the PVA matrix. Also, it was found the highest value of the swelling ratio % at (50% PVA /50% Starch) blend, while minimum values of the swelling ratio % at (75%PVA /25%Starch) blend and pure PVA film. It was observed from optical microscope that the starch granules disperse well at 25 and 30 wt.% of the starch in the blend films. Nevertheless, clustering could be observed in the polymer blend at 35, 40, and 50 wt.% of starch component. It was shown that porous and spherical voids after the samples were immersed in distilled water.

Study on crystalline phases and degree of crystallinity of the melt compounded PVA/MMT and PVA/PVP/MMT nanocomposites

Polymer nanocomposite (PNC) films comprised poly(vinyl alcohol) (PVA) and also its blend with poly(vinylpyrrolidone) (PVP) (i.e., PVA/PVP = 75/25 wt/wt%) as host matrices loaded with different amounts of montmorillonite (MMT) nanoclay up to 10 wt% were prepared by melt compounded method. X-ray diffraction (XRD) patterns of these PNC films were recorded in the appropriate angular range of 2θ values 3.8°–26° for their crystalline phase structural characterization. In comparison to the broader-type single diffraction peak for the aqueous solution cast prepared pure PVA film and that of the PVA/PVP blend film which is attributed to the hydrogen bonded isotactic and syndiotactic PVA crystals, five sharp diffraction peaks of different intensities corresponding to the evolution of various crystallites in the melt compounded PVA and PVA/PVP blend films were observed. Further, these peaks intensities were found significantly affected by the amounts of loaded MMT in these polymer matrices-based nanocomposites. It was observed that the prominent crystalline phase of the pure PVA converted into alternative tactic phases in the PVA/MMT films with the variation of MMT concentration. The prime crystalline phase of the PVA/PVP/MMT nanocomposites underwent alternative crystal structures formation abruptly on the initial loading of the 1 wt% amount of MMT in the PVA/PVP blend matrix reflecting a substantial alteration in the direction and nature of hydrogen bonding within the PVA crystal structures, and less changes were found with the further increase of MMT concentration up to 10 wt%. The effect of MMT loading on the crystallite sizes, degree of crystallinity, and the exfoliated and intercalated MMT structures in these PNC materials were analyzed in detail.

Preparation and characterization of Enteromorpha prolifera nanocellulose/polyvinyl alcohol composite films

AbstractDue to the frequent occurrence of Enteromorpha prolifera “green tide” in recent years, how to solve the ecological disaster brought by the green tide and make maximal use of the Enteromorpha prolifera have become an urgent problem. In order to realize the resource utilization of marine biomass, we extract nanofibrillated cellulose (NFC) with high aspect ratio from Enteromorpha prolifera. Filamentous NFC is successfully extracted at nanometric scale with a diameters range of 20 ~ 40 nm, a length of several microns, and a crystallinity index of 57.2%. Then NFC/polyvinyl alcohol (PVA) composite films were prepared with NFC as fillers. In addition, for comparison, nanocrystals cellulose (NCC) with small aspect ratio was isolated from microcrystalline cellulose (MCC) to prepare NCC/PVA composite films. It is shown that because Enteromorpha proliferata NFC has a higher aspect ratio, it is easier to interpenetrate with PVA to form a dense network, and the lower concentration ensures the better dispersion of NFC in the matrix, so its enhancement effect on PVA composite films is better than that of NCC. When the NFC content was 0.1 wt %, the light transmittance of NFC/PVA composite film could reach more than 94%, and the swelling degree was 250%, which is 29% lower than that of the pure PVA film, the water resistance was improved. At the same time, the tensile strength, elastic modulus and toughness were 99.1%, 1547% and 117.9% respectively, which are higher than those of PVA.

Two-dimensional materials modified layered double hydroxides: A series of fillers for improving gas barrier and permselectivity of poly(vinyl alcohol)

A series of modified 2D nanosheets (graphene oxide-layered double hydroxide, GO-LDH; boron nitride-LDH, BN-LDH; and molybdenum disulfide-LDH, MoS2-LDH) are prepared via a cost-effective, environmentally-friendly, and effortless method based on the concept of electrostatic interaction. The modified 2D nanosheet/Poly(vinyl alcohol) (PVA) nanocomposite films show a comprehensive improvement of physicochemical properties. Among the synthesized films, the O2 barrier performance of the 1% GO-LDH/PVA nanocomposite film (1.44 × 10−13 cm3 cm/cm2·s·cmHg) is 25-fold higher than that of the pure PVA film (3.68 × 10−12 cm3 cm/cm2·s·cmHg). The 1% GO-LDH/PVA shows tremendous improvement in tensile strength (84.7 MPa) and modulus (3032 MPa) values than the PVA film (46.7 and 371 MPa). Furthermore, the 2% BN-LDH/PVA nanocomposite shows the H2/CO2 permselectivity value of 102.5, which is superior to the Robeson upper bound and most reported separation films. In addition to the improved gas barrier and permselectivity performances, an exceptional combination of the thermal stability, tensile strength/modulus, flexibility, and transparency of the nanocomposite film could lead to applications in food packaging, H2 purification, and CO2 capture.

Physical Properties of Rhodamine 6G Laser Dye Combined in Polyvinyl Alcohol films as Heat Sensor

Rhodamine 6G- polyvinylalcohol (Rh6G/PVA) films were prepared via casting route at room temperature with different volume of Rh6G dye solution (5, 10, 15, 20, 25 and 30 ml). The optical properties of as-prepared films were characterized using UV–Vis spectrophotometer at a wavelength range of 200-800 nm. The absorption peak of the pure PVA film does not affect by adding the Rh6G dye solution while exhibited increase in intensity of the absorption spectrum. Furthermore, the absorption peak of Rhodamine 6G demonstrated red-shift about 10 nm. Energy band gap slightly affected by adding Rh6G dye solution. The amazing influence of heat treatment on the physical properties of Rh6G/PVA films appeared due to red-shift and decrease the energy band gap. The results exposed that the best sensitivity calculated at temperature 40 °C for as-grown Rh6G (15 ml)/PVA film around 35.74%.

Biodegradable cotton gin trash/poly(vinyl alcohol) composite plastic: Effect of particle size on physicochemical properties

Cotton gin trash (CGT), a potential lignocellulose resource was combined with poly(vinyl alcohol) (PVA) to produce the biodegradable composite plastic film. A 50:50 CGT/PVA ratio was maintained using coarse and fine CGT powder particles and the effect of particle size on the morphology, crystallinity, tensile strength, optical transmittance, thermal stability and biodegradability was investigated. Scanning electron microscope (SEM) image showed uniform distribution of CGT in PVA matrix particularly of the fine powders (~5.7 μm). The incorporation of CGT in PVA enhanced the tensile strength, biodegradability, thermal stability and induced complete UV protection. Overall, while the flexibility of the composite film decreased, the tensile strength increased 10% and 20%, respectively by the coarse and fine CGT powders when compared to the pure PVA film. Considering the fabrication cost as estimated in the study, the results point towards the immense potential of CGT as a low-cost reinforcement material for PVA to be successfully used in the production of biodegradable plastic material.

Large scale preparation of polyaniline/polyvinyl alcohol hybrid films through in-situ chemical polymerization for flexible electrode materials

Flexible electrode materials are inevitable for high-end applications such as wearable electronics, implantable microelectrodes, artificial muscles, various sensors, and biomedical devices. A simple and easy method for large scale preparation of mechanically stable and flexible electrode material using PANI and PVA films is presented. The hybrid films prepared through the chemical coating of PVA using an in-situ chemical polymerization of aniline were highly electroactive and comprised of coral-like nanowires of PANI grown on the surface of PVA films resulting large surface area and high porosity as evinced from SEM studies. FTIR spectra showed characteristic bands of PANI and PVA. Bandgap energies estimated were consistent with the electrical conductivity of the films. The doubly coated film showed an electrical conductivity as high as 4.0 × 10−2 S cm−1. The high electrochemical activity studied through cyclic voltammetry was attributed to the easy diffusion of ions through the porous nanowires of PANI on the surface of the films. Thermal studies revealed that hybrid films are thermally more stable. The tensile strength of the hybrid films was comparable with that of pure PVA film in the dry state while in the wet state the single coated film was mechanically more stable. Sorption studies showed that the mass swelling ratio of the hybrid films was decreased due to the incorporation of PANI into the hydrogel matrix. As the films were mechanically stable and highly electroactive and can be cut into pieces of any desirable size and shape we propose that they can be used as active electrode materials for sensors, supercapacitors, actuators, etc.

Electromagnetic interference shielding properties of graphene quantum‐dots reinforced poly(vinyl alcohol)/polypyrrole blend nanocomposites

AbstractGraphene quantum dots (GQDs) reinforced poly(vinyl alcohol) (PVA)/polypyrrole (WPPy) nanocomposite films with various GQDs loadings were synthesized using the versatile solvent casting method. The structural and morphological properties of PVA/WPPy/GQDs nanocomposite films were investigated by employing Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. The thermogravimetric analysis revealed enhanced thermal stability of synthesized nanocomposites while enhanced dielectric properties were also observed. The maximum dielectric constant value for PVA/WPPy/GQDs nanocomposite films was observed to be ε = 6,311.85 (50 Hz, 150°C). The electromagnetic interference (EMI) shielding effectiveness (SE) of nanocomposite films was determined in the X‐band (8–12 GHz) and Ku‐band (12–18 GHz) frequency region. The EMI SE was found to be increased from 0.8 dB for the pure PVA film to 9.8 dB for the PVA/WPPy/GQDs nanocomposite film containing 10 wt% GQDs loading. The enhanced EMI shielding efficiency of nanocomposite films has resulted from the homogenous dispersion of GQDs in PVA/WPPy blend nanocomposites. Thus, the prepared nanocomposites are envisioned to utilize as a lightweight, flexible, and low‐cost material for EMI shielding applications.

Antioxidant activity and physical properties of pH-sensitive biocomposite using poly(vinyl alcohol) incorporated with green tea extract

Our study focused on the preparation and characterization of biocomposite films consisting of poly(vinyl alcohol) (PVA) and green tea extract (GTE) with a small amount of glycerol as a plasticizer. Scanning electron microscopy (SEM) showed that both the surface and cross-section of the GTE-PVA biocomposite films were smooth and uniform. Incorporation of GTE could considerably alter the optical and mechanical properties of the pure PVA film. Notably, the GTE-PVA biocomposite films presented better water vapor and UV–vis light barrier properties and higher mechanical strength than the pure PVA film. The antioxidant ability of the biocomposite films was evaluated by measuring the 2,2-diphenyl-1-picrylhydrazyl radical scavenging and ferric reducing power in terms of the total phenolic content. The GTE-PVA biocomposite films showed higher antioxidant activity than the pure PVA film, and the antioxidant activity increased with increasing GTE concentration. The color of the GTE-PVA biocomposite films became yellow when the pH was lower than 6 and became dark red when the pH was higher than 6. Moreover, color variations were observed in the GTE-PVA biocomposite films by changing the pH. These results suggest that GTE-PVA composite films may be used as a promising antioxidant and visible pH-sensing food packaging materials.

Development of thermal insulation packaging film based on poly(vinyl alcohol) incorporated with silica aerogel for food packaging application

To develop thermal insulation packaging film, poly(vinyl alcohol) (PVA) films incorporated with silica aerogel (SA) were prepared. The effects of SA content on structural, physicochemical properties, thermal conductivity of films and evaluation of the films' thermal insulation property through chocolate packaging were investigated. The SA was dispersed uniformly in the films as SA increased from 0% to 3%. Some aggregations were observed in films containing 5% and 7% SA. And some small pores were observed in the films and their quantity increased with increasing SA. This also contributed to the films’ thermal insulation because of low thermal conductivity of air. The water vapor barrier property and thermal stability of films were improved for SA incorporation and the oxygen barrier property of films containing 3% SA was best among all developed films. All films added with SA exhibited much lower thermal conductivity than the pure PVA film and it decreased significantly with increasing SA. The result of its application for chocolate packaging showed that the films incorporated with SA can prevent chocolate from softening better and the protective effect increased with increasing SA. These films will be prospective to be used in multilayer packaging systems for temperature-sensitive foodstuffs packaging applications.

Few-Layer Hydroxyl-Functionalized Boron Nitride Nanosheets for Nanoscale Thermal Management

Boron nitride nanosheets (BNNSs) are widely used as fillers to increase the thermal conductivity of a substrate. However, the solvent resistance of BNNSs limits their widespread application. In this paper, hydroxyl functionalized boron nitride nanosheets (OH-BNNSs) were prepared through a one-step aqueous shear exfoliation process. The dangling bonds were formed during the exfoliation process and were attacked by water molecules, and thereby hydroxyl functionalization of BNNSs was achieved. The OH-BNNSs were added to poly(vinyl alcohol) (PVA) to prepare a nanocomposite with high thermal conductivity. The high-speed dispersive homogenizer was selected as the shear-exfoliating device, water as solvent, and sodium dodecyl sulfate (SDS) as surfactant. The effects of operating conditions on the concentration of few-layer OH-BNNSs were systematically studied. Under the optimized conditions, 0.88 mg/mL of OH-BNNSs was obtained. The as-obtained OH-BNNSs were filled in PVA to obtain composite film. The in-plane thermal diffusivity of OH-BNNSs-PVA films reached 9.03 mm2/s, which was 40-times the in-plane thermal diffusivity of the pure PVA film and 1.6-times the in-plane thermal diffusivity of the PVA composites filled by BNNSs prepared from ultrasonic exfoliation. The reasons were attributed to better dispersibility in PVA aqueous solution for OH-BNNSs. This paper provided a simple, scalable, and environmentally friendly preparation method for OH-BNNSs.

Synthesis of Montmorillonite Clay/Poly(vinyl alcohol) Nanocomposites and Their Mechanical Properties

The montmorillonite/poly(vinyl alcohol) (MMT/PVA) nanocomposites films were synthesized by aqueous dispersion of MMT clay to PVA solution at 70-75 °C for 4 h. The average thicknesses of the MMT/PVA films were 85-120 μm. The amount of clay was varied between 0-5 wt%. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed the coexistence of exfoliated and intercalated structure of MMT clay in PVA. The Raman analysis of 1 wt% MMT/PVA showed, increased peak intensity at 1146.5 cm-1, that is indicator of higher crystallinity compare to pure PVA. Dynamic mechanical analysis (DMA) of MMT/PVA nanocomposite films showed an increase in the storage modulus. The optimum value of storage modulus obtained was 8,752 MPa on dispersing 1.0 wt% MMT clay in the PVA yielding 20.0% increase in the storage modulus compare to the pure PVA films. Thermo-gravimetric, analysis (TGA) of the MMT/PVA nanocomposite films also showed the increase in the thermal stability with respect to pure PVA films. The 1.0 wt% MMT clay loading in PVA, improved the thermal stability of MMT/PVA to 325 °C compared to 250 °C for pure PVA.

Microstructure and optical properties of Ni2+ doped PVA for optoelectronic devices

Different wt.% of Ni2+- doped Poly (vinyl alcohol), PVA, films are synthesized by a low-cost casting method. XRD, SEM and FTIR spectroscopy are used to study the microstructure of the composite samples. The degree of semi-crystallinity for all Ni2+-doped PVA (NPVA) and pure PVA films decreases and the amorphous order dominated in 3.7 wt% Ni2+-doped PVA (NPVA5) film as established by studying the spectroscopy of XRD and FT-IR. The increment of the Ni2+-doping level in PVA led to a formation of non-homogeneous particle size with an average value range from 1.03 μm to 4.47 μm for 0.027 wt% Ni2+-doped PVA (NPVA1), and NPVA5 films, respectively. UV–Vis-IR transmittance and absorption spectroscopies are specified for measuring the optical parameters. The indirect energy gap (Eig) decreases to 4.85 eV for NPVA5 film, and the direct energy gap, Eg, to 1.36 eV for the same sample. However, owing to the complex construction between Ni2+-ions and the matrix of PVA, the transition strength (Ed), the indices of refraction (n, n∞), and oscillator wavelength (λ0) increase, while the excitation energy (Es) decreases with further wt.% of Ni2+-ions. Due to the optical properties of the films, they are suitable to be inserted in different optoelectronic applications.

The influence of crosslinking temperature on the spectroscopic, thermal, andmechanical properties of poly(vinyl alcohol)/zeolite composites

The aim of this study was to understand the effect of crosslinking temperature on the spectroscopic, thermal, and mechanical properties of poly(vinyl alcohol) (PVA)/zeolite composites. The PVA nanocomposite films were prepared using the solvent casting method with tartaric acid as the crosslinker. The changes in the structures of pure PVA film and powder clinoptilolite (CL) and nanocomposite films were analyzed by means of ATR-FTIR spectroscopy. The effect of both crosslinking temperature and CL on the composite films prepared by the addition of constant CL to the polymer matrix at different crosslinking temperatures (series II) and pure PVA films prepared with different crosslinking temperatures (series III films) shows that the tensile strengths increase with increasing crosslinking temperature, while the elongation at break of films decreases due to the crosslinking temperature and CL. The differential scanning calorimetry results show that the crosslinking temperature leads to an increase in the glass transition ($T_{g})$ of nanocomposites. According to the results of this study, both zeolite and crosslinking temperature affect the thermal and mechanical properties of the material. These results may be used for membrane technology.

Influence on loading terbium manganate on optical, thermal and electrical properties of polyvinyl alcohol nanocomposite films

In this article, optical, thermal and electrical properties of different wt% of TbMnO3 (TMO) nanoparticles (NPs) loaded poly(vinyl alcohol) (PVA) films are reported in detail. The films are structurally characterised by X-ray diffraction spectroscopy and field emission scanning electron microscopy (FESEM). Optical parameters such as optical band gap energy $$\left( {{E_g}} \right)$$ , Urbach energy $$\left( {{E_U}} \right)$$ are calculated. Red shift in the absorption band of the nanocomposite films indicates the complex formation between the nanofiller and the matrix. Thermal strength increases in TMO-PVA films than the pure PVA film. A reduction in the glass transition temperature $$\left( {{T_G}} \right)$$ of the nanocomposite films is noticed with the insertion of TMO NPs in the PVA matrix. DC conductivity of the samples is explained by Mott’s variable range hopping model, Greave’s model, small polaron hopping model, non-adiabatic hopping model to explain the conduction mechanism. Modified Cole–Cole model explains the frequency variation of dielectric spectra. The relaxation peak position shifts towards lower frequency region with the inclusion of TMO filler in the PVA matrix indicating the decrease in mobility of the dipolar functional groups in the polymer chain. Modified Kohlrausch–Williams–Watts model is applied to explain the frequency dependent electric modulus spectra. AC conductivity of the films is explained by Jonscher’s power law. Correlated barrier hopping model is applied here. The presence of large current of the films at zero voltage may be due to the presence of ferroelectricity in the nanocomposite systems. Oxygen related defect states exist in the polymeric system which exhibit trapping of the charge carriers.