Loss Factor Values Research Articles

A Novel Approach of the Viscoelasticity of Axially Functional Graded Bar and Application of Harmonic Vibration Analysis of an Isotropic Beam as Support

The use of smart materials and passive controllers in modern technologies has stimulated the study of vibration in elastic systems with viscoelastic damping. It is also possible to create components with precise material distribution coefficients and distinct properties, such as Functionally Graded Materials. This work investigates the resonant frequency characteristics of a beam supported at its ends by Axially Functionally Graded (AFG) viscoelastic bars using the finite element method. The set of equations governing motion is obtained by assuming Euler–Bernoulli beam theory for the beam and bar theory for the bars using Lagrange’s equations. The material properties of the functionally graded bar is assumed to vary through the length according to the power law distribution. The longitudinal loss factor values are used to define the internal damping coefficient, which is also dependent on the Young’s modulus value varying along the bar. The effects of the length-varying material properties and internal damping of the FG support bars on the force transmission TR and frequency parameters λ are examined in detail. No study has been found in the literature on the vibration of viscoelastic FG bar-supported beams subjected to a harmonic force at the centre point. It is shown that using bars formed with combinations of different materials considering material damping will be useful to keep the vibration level and force transmission at a certain value and control the frequency parameters.

Microwave cavity antenna for automatic detection of chicken breast muscles affected by wooden breast defect

Over the past years, artificial selection for meat-type (broiler) chickens has resulted in improved production efficiency, but also in an increased incidence of skeletal muscle abnormalities. In particular, wooden breast (WB) abnormality causes abrupt changes in meat quality and enormous economic losses. Thus, the poultry processing industry requires a reliable method to detect the abnormality in production lines in a non-destructive and contactless way. The present research aimed to evaluate the effect of WB on dielectric properties to develop a potential online technique to distinguish unaffected from affected breasts. Sixty-five pectoralis major muscles were picked 3 h post-mortem from the same flock (42-day-old broilers, 2.8 kg average live weight) and classified by visual inspection according to their phenotype as normal (N, not showing not any signs of the WB condition; n = 33) or WB (exhibiting extensive hardened areas and stiffness perceived by manual palpation throughout the entire fillet; n = 32). WB muscles exhibited remarkably higher values of dielectric constant and loss factor in a wide range of the explored frequencies (200 MHz–14 GHz), suggesting higher water mobility and a higher solvate capacity; this makes the electromagnetic technique for classification promising. Based on the above evidence, a rapid microwave electric technique in the range 1.5 GHz–3 GHz was developed for the online detection of WB. Indeed, combining the use of a cavity antenna (vector network analyzer instrumental chain with partial least square – discriminant analysis), this technique correctly classified 100% of the validation test set.

Improved wet skid resistance of NR/SBR composites induced by irradiation vulcanised styrene-butadiene rubber particles

Improving the wet skid resistance of tire tread is very important for the safety of vehicle driving. Using a novel ultrafine full-vulcanised powdered styrene-butadiene rubber (UFPSBR), this work prepared an advanced UFPSBR/nature rubber (NR)/styrene-butadiene rubber (SBR) composites used for the tire tread. On one hand, the UFPSBR improves the loss factor (tanδ) values of the UFPSBR/NR/SBR composites in temperature range from 0 °C to 10 °C, indicating that the UFPSBR modified tire tread has better wet skid resistance. On the other hand, the UFPSBR increases the surface roughness and complex modulus of the UFPSBR/NR/SBR composites while decreasing the water contact angle of the UFPSBR/NR/SBR composites, which is conducive to increasing the wet skid resistance of tire tread by puncturing the water film or leading a thinner water film between tire tread surface and road surface. Above researches are more comprehensive and benefit for studying the advanced green tire with high wet skid resistance.

Dynamic tensile viscoelastic properties of porcine periodontal ligament.

The periodontal ligament plays a significant role in orthodontic and masticatory processes. To explicitly investigate the effects of dynamic force amplitude and frequency on the dynamic tensile properties of the periodontal ligament, in vitro tensile experiments were conducted using a dynamic mechanical analysis at various dynamic force amplitudes across a wide frequency range. Storage modulus, loss modulus, and loss factor values were measured. A Maxwell constitutive model based on modulus was established to describe the dynamic mechanical properties of the periodontal ligament. The results showed that the storage modulus ranged from 29.53MPa to 158.24MPa, the loss modulus ranged from 3.26MPa to 76.16MPa, and the loss factor values all increased with higher frequencies and higher dynamic force amplitudes. Based on the parameters obtained from the fitting results, it is evident that the short-term response has a more pronounced impact on the elastic response of the periodontal ligament than the long-term response. Increasing the dynamic force amplitude and its frequency amplified the viscous effects of the periodontal ligament and enhanced energy dissipation. The proposed constitutive model further demonstrated that the periodontal ligament acts as a viscoelastic biomaterial. These findings have implications for future research on the periodontal ligament.

Love waves propagation in layered viscoelastic waveguides characterized by a Zener model

This paper describes a theory of surface Love waves propagating in lossy waveguides consisting of a viscoelastic layer deposited on a semi-infinite elastic substrate. The Zener model to describe the viscoelastic behavior of a medium is used. This simple model captures both the relaxation and retardation. A new form of the unsteady momentum equation for viscoelastic waveguides has been established. By using appropriate boundary conditions, an analytical expression for the complex dispersion equation of Love waves has been deduced. The influence of the loss factor and the ratio of shear moduli of the surface layer on the dispersion curves of Love waves velocity and attenuation is analyzed numerically. The numerical solutions show the dependence of the velocity change and the wave attenuation in terms of the loss factor and the ratio of shear moduli. The obtained results show that the change in the ratio of shear moduli can represent a hardening or softening effect of the surface layer. These effects depend on the loss factor value of the surface layer. In addition, these results are novel, fundamental and can be applied in the characterization of the viscoelastic properties of soft biomaterials and tissues, in nondestructive testing of materials, in geophysics and seismology. Thus, the obtained complex dispersion equation can be very useful to interpret the experimental measurements of Love waves properties in viscoelastic waveguides.

Structure and dynamics heterogeneity in poly(vinyl acetal)s: The effect of side group length

Understanding on the structure and dynamics of poly(vinyl acetal)s is insufficient due to the complicated chemical structure and amorphous nature of this type of polymers. In this work, we investigate the effect of side group length on structure and dynamics heterogeneity at different length scales spanning from side group, segment, and polymer network by combing dynamic mechanical analysis (DMA), dielectric relaxation spectroscopy (DRS), solid-state NMR, and differential scanning calorimetry analysis (DSC). By increasing the length of acetal side group, its intrinsic dynamics slows down. Taking into account the scale of segment and networks, with the increase of acetal group length, the formation of cross-linking sites formed by the hydroxyl-rich domain is suppressed, the relaxation distribution of the segment widens, and the volume fraction of rigid component decreases. The effect of side group length on the structure and dynamics heterogeneity of poly(vinyl acetal)s at different scales results in significant changes in material properties such as the non-monotonic change in loss factor value (tan δ) and a monotonous reduction in glass transition temperature (Tg).

Dielectric behavior and impedance spectroscopy of Niobium substituted Lanthanum based orthovanadates at high temperatures

We present the detailed study of the temperature dependent dielectric properties, impedance spectroscopy and electrical conductivity of LaV1−xNbxO4 (x=0–1) samples prepared by the solid-state reaction method. The dielectric constant (ϵr′) increases (decreases) with increase in the temperature (frequency); while, the magnitude of ϵr′ remains almost invariant (order of 104 at 100 Hz and 600 °C) with x. The single phase x=0 (monoclinic-monazite, P21/n) and x=1 (monoclinic fergusonite, I2/a) samples show the lower values of loss factor [tanδ= (4–8)] as compared to the x=0–0.8 samples [tanδ= (12–18)] having mixed tetragonal and monoclinic phases, which indicates the strong correlation between the crystal structure and the dielectric properties. The real part of impedance (Z′) decreases with both temperature and frequency, and the observed weak relaxation remains almost unaltered with x. The imaginary part of impedance (Z′′) shows strong relaxation peaks shifting towards higher temperatures with frequency, which is attributed to the effect of grains, grain boundaries, and electrodes in the samples. The activation energy of the relaxation process is estimated to be 0.8–1.0 eV for the x=0–0.6 samples, and ≈1.4 eV for the x=0.8; whereas the x=1 sample shows two values (≈0.5 eV and ≈1.0 eV) in the higher and lower temperature range, respectively. Further, the change in total conductivity with the angular frequency, which found to be in the range of 10−3 to 10−5 S/m, is fitted using the Jonsher power law. The analysis suggests the overlapping large polaron tunneling (OLPT) model for all the samples, whereas the x = 1 sample exhibit a transition near 480 °C and at higher temperatures it shows non-overlapping small polaron tunneling (NSPT) and quantum mechanical tunneling (QMT). This transition is corroborated by the tangent loss curves and may be associated with the change in structure.

Thermoplastic Electromagnetic Shielding Materials from the Integral Recycling of Waste from Electronic Equipment.

The European Green Deal's goals are anticipated to be fulfilled in large part thanks to the New Circular Economy Action Plan. It is believed that recycling materials will have a significant positive impact on the environment, particularly in terms of reducing greenhouse gas emissions and the impacts this will have on preventing climate change. Due to the complexity of the issue and its significant practical ramifications, the activity of Waste Electrical and Electronic Equipment (WEEE) collection networks is a subject of interest for researchers and managers, in accordance with the principles that recent laws have addressed in a large number of industrialized countries. The goal of this paper is to characterize and obtain composite materials using an injection process with a matrix of LDPE, PP, and HDPE, with up to a 10% addition of nonmetallic powders from PCBs and electronic parts from an integrated process of WEEE recycling. The composites present relevant thermal, electrical, and mechanical properties. Such composite materials, due to their relevant dielectric properties, may be further tested for applications in electromagnetic shielding at frequencies above 1 kHz, or for electromagnetic interference/electromagnetic compatibility (EMI/EMC and ESD) applications at lower frequencies due to their superior dielectric loss factor values, associated with relevant behaviors around exploitation temperatures, mainly for the electric, electronic, or automotive industries.

Properties of PBZTS Ferroelectric Ceramics Obtained Using Spark Plasma Sintering.

In this paper, spark plasma sintering was used to obtain and investigate (Pb0.97Ba0.03)(Zr0.98Ti0.02)1-xSnxO3 (PBZTS) ceramic materials for x = 0, 0.02, 0.04, 0.06, and 0.08. Crystal structure, microstructure, dielectric and ferroelectric properties, and electrical conductivity tests of a series of samples were carried out. The SPS sintering method ensures favorable dielectric and ferroelectric properties of PBZTS ceramic materials. X-ray studies have shown that the material has a perovskite structure. The samples have a densely packed material structure with properly crystallized grains. The fine-grained microstructure of the PZBZTS material with high grain homogeneity allows the application of higher electric fields. Ceramic samples obtained by the SPS method have higher density values than samples obtained by the classical method (FS). The permittivity at room temperature is in the range of 245-282, while at the phase transition temperature is in the range of 10,259-12,221. At room temperature, dielectric loss factor values range from 0.006 to 0.036. The hysteresis loops of PBZTS ceramics have a shape typical for ferroelectric hard materials, and the remnant polarization values range from 0.32 to 0.39 µC/cm2. The activation energy Ea values of the PBZTS samples result mainly from the presence of oxygen vacancies. The PZT material doped with Ba and Sn and sintered via the SPS method has favorable physical parameters for applications in modern devices such as actuators or pulse capacitors.

Effect of various sintering methods on the properties of PZT-type ceramics

The paper shows how different sintering methods affect the basic characteristics of PZT-type multicomponent ceramics. A perovskite-structured multicomponent ceramic of lead zirconate titanate (PZT) type doped with Mn4+, Sb3+, W6+, and Ni2+ and with a chemical composition of Pb(Zr0.49Ti0.51)0.94Mn0.015Sb0.01W0.015Ni0.03O3 was obtained. Ceramic powders were synthesized using the calcination method. Three sintering methods, including: (i) pressureless free sintering (FS), (ii) hot pressing (HP), and (iii) spark-plasma sintering (SPS), were used for the final sintering. The electrophysical measurements of the PZT-type ceramics, including scanning electron microscopy microstructure (SEM), X-ray diffraction (XRD), dielectric, ferroelectric, piezoelectric properties, and DC electrical conductivity, are presented. The microstructure of the samples is characterized by densely packed grains with correctly crystallized grain shapes but with different average grain sizes for each sintering technology used. At room temperature (RT), PZT ceramic samples have high values of resistivity ρDC (from 7.25 × 108 Ωm to 1.14 × 109 Ωm), high values of permittivity (from 1048 to 1307), and low values of dielectric loss factor (from 0.008 to 0.02). Samples with the most favorable dielectric, ferroelectric, and electromechanical parameters were obtained using the FS and HP sintering methods. In the case of spark-plasma sintering (SPS), the assumed improvement in the electrophysical properties of the P-SPS ceramic sample was not obtained. Also, the most advantageous piezoelectric parameters have ceramic samples obtained by the FS and HP methods. The conducted tests verify that all the obtained ceramic compositions have a complete set of parameters suitable for micromechatronic applications.

Adaptive segmentation-based evaluation of material properties of dielectric sheets using microwave NDE

ABSTRACT Composite materials/structures are rapidly advancing, offering improved product efficiency, cost-effectiveness, and superior specific properties. These materials find increasing applications in corrosion resistance and load-carrying structures across industries such as aerospace, wind turbines, transportation, and medical equipment. Therefore, ensuring reliable non-destructive evaluation of composites is crucial to address safety concerns and minimise maintenance expenses. The microwave non-destructive evaluation (NDE) method is particularly well-suited for characterising the material properties of composites. In our study, we utilise a large flange open-ended rectangular waveguide (OERW) probe, measuring 152 mm x 152 mm, to assess the complex reflection coefficient of dielectric materials. This measurement enables the extraction of essential material parameters using a forward electromagnetic model combined with an optimised method. To enhance accuracy, we introduce an iterative conjugate gradient descent (CGD) optimiser with adaptive segmentation. This approach effectively avoids local minima and reduces disparities in integrand values, resulting in precise measurements of material properties. Our proposed method provides estimations of the dielectric constant within a range of 1 to 10 and accurately determines sample thickness with a controlled limit of 3% error across all samples. Furthermore, we observe that as the loss-factor value decreases, the error in calculating the loss-factor of samples increases, which is supported by numerical analysis.

Effect of surfactants on the properties of rubber composites prepared from pyrolytic carbon black/natural latex via wet blending method

Pyrolytic carbon black (CBp) is the main by-product of waste tire pyrolysis. CBp has high ash content and poor surface activity which leads to the composites reinforced with CBp has lower performance than composites reinforced with commercial carbon black, making it difficult to meet the requirements of tire. In order to realize the application of CBp in tires, the effect of surfactants on the properties of rubber composites prepared by wet mixing of CBp/natural latex was investigated. In the experimental process, sodium stearate (C17H35COONa), sodium dodecylbenzene sulfonate (C18H29NaO3S), and sodium p-styrenesulfonate (C8H7NaO3S) were used to improve the surface activity and uniform dispersion of the CBp in the natural rubber matrix. The experimental results showed that the dispersity of C18H29NaO3S and C8H7NaO3S modified CBp in rubber matrix has [X] and [Y] values of 7.5 and 7.9, and 9.3 and 9.5, respectively, and the dispersion of these rubber composites is significantly better than that of C17H35COONa. The rubber composites prepared by C18H29NaO3S and C8H7NaO3S surfactants has the better physical and mechanical properties. The rubber composite prepared by C18H29NaO3S has the highest tensile strength of 25.63 MPa, which increment in tensile strength is 15.6% compare to the rubber composite prepared by C17H35COONa. Meanwhile the dynamic mechanical properties of rubber composites prepared by modifying CBp with C18H29NaO3S and C8H7NaO3S are better than CBp with C17H35COONa. The C8H7NaO3S modified CBp/rubber composite has the lowest loss factor (tanδ) value at 60°C, and the C18H29NaO3S modified CBp/rubber composite has the highest tanδ value at 0°C.

Elucidation of Structural, Morphological, Electrical Parameters and Anti-bacterial Activity of Polyaniline-Nanocomposite: New Paradigm of Controlling Bacterial Activity.

In this communication, we purpose an alternative electrical method to determine the anti-bacterial activity of compounds. Polyaniline/magnetite (Fe3O4/PANI) and polyaniline/hydrochloric acid (HCl/PANI) nanocomposites have been prepared. We have tested the anti-bacterial activity of Fe3O4/PANI and HCl/PANI nanocomposites by Agarwell Diffusion Assay and Bacterial Inhibition Assay method. The electrical characteristics of the prepared composites have been measured. The doping of 12% of Fe3O4 in PANI caused a substantial increase in anti-bacterial activity. The observed bacterial inhibition is in agreement with optimized values of resistivity, loss factor, quality factor, and spontaneous magnetization. Sample 2 associated with 12% Fe3O4-PANI composites has a high resistivity of 1.70 x 106Ω.m among all prepared composites. The magnetic character and insulating nature of Fe3O4 influenced the investigated parameters. The morphological variation of prepared composites is also consistent with electrical parameters. The alleviated energy zone formed by the magnetic behavior of Fe3O4 and interfacial polarization of PANI mitigates the polarization/field of charge carriers of bacteria. These effects altogether diminish the energy of bacterial zone revealed in the experiment. The tuning of electrical parameters provides an alternative to control bacterial growth in various compounds. The proposed method of electrical characterization for the detection of the anti-bacterial activity of the compounds can be very useful in terms of time and cost in contrast to the lab tests performed in biological labs. After implementing an electrical parameter standard equivalent to anti-bacterial activity, real-time detection can be performed by electrical parameters in the fields outside without any hassle, which otherwise is not possible for biological labs.

Hydration dominates dielectric spectroscopy-based high accuracy quantification of lactose content in cow's milk.

Lactose is a critical factor in the quality of milk and dairy products. Achieving high accuracy and rapid detection of lactose content in cow's milk remains a challenge. Dielectric spectroscopy has emerged as a promising tool for detecting food components. We explored the effect of lactose content on the dielectric spectra of cow's milk and proposed a rapid analytical method for the quantitative determination of lactose content in cow's milk with high accuracy based on dielectric spectra. We obtained the dielectric spectra of 316 cow's milk samples in the frequency range of 20 to 4500 MHz and noticed a strong negative correlation between the lactose content and the value of the dielectric loss factor (ε'') below 1500 MHz. Lactose doesn't affect cow's milk dielectric properties by excluded volume effect but dominates the effect on the dielectric properties of cow's milk by hydration. The support vector regression (SVR) model based on the variable importance in projection (VIP) has the best prediction performance for lactose content. Its root-mean-square error of prediction set (RMSEP) and residual prediction deviation (RPD) is 0.29 g kg-1 and 6.968, respectively, and its prediction performance is better than that of the currently reported near-infrared (NIR) method and other methods. Despite the weak polarity of lactose molecules, its hydration is a significant factor affecting the dielectric properties of milk. This study provides a basis for high accuracy and rapid quantitative detection of lactose in cow's milk based on dielectric spectra. This article is protected by copyright. All rights reserved.

Preparation of Fe3O4-carbon black/poly(vinylidene fluoride) composites with enhanced properties

In this work, the Fe3O4-carbon black filler was obtained from an in-situ coprecipitation method followed by the modification of the heptadecafluorodecyltrimethoxysilane and the Fe3O4-carbon black/poly(vinylidene fluoride) (PVDF) composites with enhanced properties were prepared by a simple solution blending-water precipitating method. The Fe3O4-carbon black distributed well in the PVDF matrix, which was confirmed by the SEM. According to the results of FTIR and WAXD, a lot of useful polar crystalline phases of PVDF formed in the Fe3O4-carbon black/PVDF composites. The electrically conductive ability, the dielectric permittivity, the dielectric loss factor, and the magnetic saturation value of the Fe3O4-carbon black/PVDF composite increased with the increasing loading amount of Fe3O4-carbon black filler. Especially, when the Fe3O4-carbon black was 5 wt.%, the dielectric permittivity of Fe3O4-carbon black/PVDF composite reached as high as 23.5 at 1000 Hz with a relatively low dielectric loss factor value of 0.38 and a magnetic saturation value of 0.64 emu/g.

The effect of thermal aging on solid insulating materials: A case study for dielectric loss and dissipation factor based evaluations under different voltage levels and frequencies

Investigating the dielectric performance phenomenon in insulating materials is critical for condition monitoring and early failure diagnosis. In this study, the effect of thermal aging on dielectric losses and dissipation factors of four insulating materials are investigated: PET, SBR/NR, presspaper and HDPE. A series of measurements at 4 kV and 10 kV with eight different frequencies between 50 Hz and 400 Hz are used to determine the dielectric loss and dissipation factor values of the materials during aging process. Thus, the non-ideal structure of electrical networks and the presence of harmonics are considered. Referring to the results, it is found that the level and frequency of the applied voltage greatly affects the performance of the materials. Also, it is seen that thermal aging have a significant impact on the dielectric properties of the materials. Furthermore, thermal aging effect on the results of different frequencies differs according to the material type.

Effects of carboxymethyl chitosan on the oxidation stability and gel properties of myofibrillar protein from frozen pork patties

The effect of carboxymethyl chitosan (CMCH) on the oxidation stability and gel properties of myofibrillar protein (MP) from frozen pork patties was investigated. The results showed that CMCH could inhibit the denaturation of MP induced by freezing. Compared with the control group, the protein solubility was significantly (P < 0.05) increased, while the carbonyl content, the loss of sulfhydryl groups, and the surface hydrophobicity were decreased, respectively. Meanwhile, the incorporation of CMCH could alleviate the influence of frozen storage on water mobility and reduce the water loss. With the increased concentration of CMCH, the whiteness, strength, and water-holding capacity (WHC) of MP gels were significantly improved, in which the maximum value was at addition level of 1 %. In addition, CMCH inhibited the decrease in the maximum elastic (G′) value and loss factor (tan δ) value of samples. By scanning electron microscopy (SEM) observation, CMCH stabilized the microstructure of the gel and maintained the relative integrity of the gel tissue. These findings suggest that CMCH could be used as a cryoprotectant to maintain the structural stability of MP in pork patty during frozen storage.

3D printed negative stiffness meta-structures with superior energy absorption and super-elastic shape-recovery features

The aim of this paper is to create novel 3D cubic negative stiffness (NS) structures (NSSs) with superior mechanical performances such as high energy absorption, shape recovery, super-elasticity, and reversibility. The conceptual design is based on an understanding of geometrical influences, non-linear buckling-type instability, snap-through mechanism, elasto-plastic deformation growth and plastic hinges. A finite element (FE) based computational model with an elasto-plastic material behavior is developed to design and analyze NSSs, saving time, material, and energy consumption. Material samples and meta-structures are 3D printed by selective laser sintering printing method. Material properties are determined via mechanical testing revealing that the printing process does not introduce much anisotropy into the fabricated parts. Experimental tests are then conducted to study the behavior of novel designs under loading–unloading cycles verifying the accuracy of the computational model. A good correlation is observed between experimental and numerical data revealing the high accuracy of the FE modeling. The structural model is then implemented to digitally design and test NSSs. Effects of the geometrical parameters of the negative stiffness members under three cyclic loading are investigated, and their implications on the non-linear mechanical behavior of NSSs under cyclic loading are put into evidence, and pertinent conclusions are outlined. In addition, the dissipated energy and loss factor values of the designed structures are studied and the proposed unit cell is presented for the energy absorbing systems. The results show that the structural and geometry of energy absorbers are key parameters to improve the energy absorption capability of the designed structures. This paper is likely to fill a gap in the state-of-the-art NS meta-structures and provide guidelines that would be instrumental in the design of NSS with superior energy absorption, super-elasticity and reversibility features.

Investigation of calcium substitution on magnetic and dielectric properties of Mg–Zn nano ferrites

In this work, an efficient, cost-effective, and less time-consuming citrate precursor wet chemical approach was employed to prepare a series of Calcium (Ca) doped Magnesium–Zinc ferrite of composition Mg0.4Zn0.6-xCax Fe2O4 (0.0 ≤ x ≤ 0.6). X-ray diffraction (XRD), Scanning electron microscopy (SEM) with Energy dispersive X-ray (EDX) analysis confirmed the spinel structure and nanometric size of the particles. Williamson-Hall (W–H) plots were drawn by making use of XRD data and calculated values of lattice strain were found in the range (3.00 × 10−3 to 9.09 × 10−3) for various concentrations of calcium. The cubic spinel structure of produced ferrites was also verified by three active Raman modes (A1g, Eg, and T2g). In the Vibrating sample magnetometer (VSM) study, an “S” shape curve shows the low values of coercivity for all the samples in the range 59–105 Oe. For all Ca concentrations, the dielectric loss tangent values were evaluated to be extremely low 0.03 to 0.18 at 1 MHz frequency. The highly magnetic nature and very low value of loss factor make this prepared nanoferrite material best suited for the manufacturing of high-frequency application devices.

Thermal and Dielectric Behaviour of Polymer-Based Nanocomposites Flexible Sheets as Highly Stable Dielectric Materials

The silica zinc oxide nanoparticles filled poly-vinylidene-fluoride (PVDF)-based nanocomposite flexible sheets (NC FSs) are synthesized by co-precipitation method. The X-ray diffraction patterns reveal the development of various diffraction planes related to zinc oxide (ZnO) and SiO2 phases. The crystallinity of ZnO phase is decreased with increasing weight percent (wt.%) of silica nanofillers (NFs). The scanning electron microscope microstructure of synthesized PVDF-based NCs FSs is changed with increasing wt.% of silica NFs. The energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy analyses confirm the presence of different elements and the formation of chemical bonding between them. In high temperature region, the weight-loss of synthesized PVDF-based NCs FSs is decreased from 89.90% to 49.26% with increasing wt.% of silica NFs. The values of dielectric permittivity, loss-factor, impedance, and AC-conductivity of PVDF-based NC FSs synthesized for maximum amount of silica NFs are found to be 13.7, 0.03, 0.16 MΩ, and 19.9 × 10 − 6 S/m, respectively. Results show that the synthesized PVDF-based NC FSs are the potential candidates of light emitting diodes and energy storage devices.