Increase In Content Of Nanoparticles Research Articles

The effect of silica nanoparticles on the shock adiabatic relation and tensile strength in polyurethane

This work exploded the effect of silica nanoparticles on shock adiabatic relation and tensile fracture in polyurethane based on atomistic simulations. It is found that the non-uniform interface structures introduced by nanoparticles can increase the shock impedance, which also leading to increased twisting of polyurethane chains and the generation of local hotspots near the nanoparticles. The interface structures near the nanoparticle consists of polyurethane chains with a high gyration radius, and the average gyration radius increases approximately linearly with the increase in nanoparticle content. At lower shock velocity, the potential energy increment initially increases and then decreases with the increase in nanoparticle content. Bond analysis reveal that flexible segments dominate the bending and twisting deformations of polyurethane, while nanoparticles enhance the corresponding deformation degrees. Furthermore, nanoparticles can serve as void nucleation sites for early-stage tensile damage, resulting in a decrease in fracture strength. Differing from metals, the relationship between tensile strength and fracture temperature follows a more linear law. Nanoparticles inhibit the later growth and coalescence of voids by increasing the temperature and steric hindrance. The density and size distribution characteristics of voids are consistent with the changes in potential energy during the shock compression process. Unlike classical spallation, the curled polyurethane chains in the tensile region gradually orient along the shock direction, evolving into a void-fiber structure.

Influence of Zinc Oxide Nanoparticles on Flame Resistance in Wood Plastic Composites

The interest in wood plastic composites (WPCs) has increased in recent years. The utilization of environmentally friendly materials has been of great significance due to the overwhelming pressure on nature. As a widely used material, plastic is, however, easily combustible due to its structure. In this study, WPCs were reinforced with zinc oxide (ZnO) nanoparticles. The effect of higher content of ZnO nanoparticles (1, 3, 5, 10 %) on WPCs thermal stability and fire performance was investigated. Thermogravimetric analysis (TGA) clearly demonstrated that nanoparticles acted as a shield, which inhibited heat transfer and increased the degradation temperature thanks to covering the surface of materials. Free radicals accelerated the thermal degradation of neat-HDPE (high-density polyethylene) by oxidative reactions, while ZnO nanoparticles reduced the degradation velocity. Moreover, the increase in nanoparticle content significantly affected the residue. The fire performance of WPCs was also investigated by the limit oxygen index (LOI) test. While neat-HDPE flamed with dripping, ZnO nanoparticles made flaming difficult for WPCs. Therefore, the LOI values increased with increasing nanoparticle content up to 28.5 %, which indicated the need for more oxygen. The improvement reached up to 54 % compared to neat HDPE. Moreover, the char forming was also improved, which helped enhance the fire resistance. The scanning electron microscope (SEM) investigation indicated that nanoparticles were well dispersed in the matrix. However, the tendency to agglomerate increased with the increase of concentration. The ability of carbonization of wood fiber surface during the combustion also contributed to improving thermal stability and fire performance.

Numerical Simulation and Comparison of the Mechanical Behavior of Toughened Epoxy Resin by Different Nanoparticles.

Adding nanoparticles as the second phase to epoxy can achieve a good toughening effect. The aim of this paper is to simulate the toughening behavior of epoxy resin by different nanoparticles using a convenient and effective finite element method. The mechanical behaviors of epoxy resins toughened by nano core-shell polymers, liquid rubber, and nanosilica were compared by numerical simulations using the representative volume element (RVE). It is indicated that the addition of a nano core-shell polymer and liquid rubber can reduce the tensile properties of epoxy resin, while nanosilica is on the contrary. With the increase of nanoparticle content, the length of crack propagation decreases, and the toughening effect of the nano core-shell polymer is the best. The failure mode is determined by the particle/matrix interface when the modulus of the nanoparticle is much larger than that of epoxy resin. However, it is determined by the interface properties of the particle/matrix and the modulus of nanoparticles in other cases. The results provide a theoretical basis for toughening nanoparticle selection of nanoparticle-toughened epoxy resin and other similar simulations in the future.

Enhanced optical, thermal and electrical properties of chlorinated natural rubber/zinc ferrite nanocomposites for flexible electrochemical devices

This work focused on optical, thermal stability and temperature-dependent electrical properties of chlorinated natural rubber (Cl-NR)/zinc ferrite (ZnFe2O4) nanocomposites. The insertion of ZnFe2O4 into Cl-NR showed a decrease in bandgap energy was revealed by UV spectroscopy. The thermal stability of rubber nanocomposites increased with an increase in the content of nanoparticles. The AC conductivity, dielectric constant and dielectric loss tangent of the nanocomposites were higher than the parent polymer and these properties increased with an increase in temperature and frequencies. The non-ohmic type of AC conductivity proves the dynamic relaxation process of typical semiconducting materials. The activation energy calculated from AC conductivity decreases with the temperature. The semi-circular arc obtained from Cole-Cole plot proved the temperature enhanced conductivity of the nanocomposites. The DC conductivity increased with the increase in content of nanoparticles and the changes in conductivity were correlated with different theoretical approaches such as Scarisbrick, Bueche and McCullough model. The experimental conductivity of nanocomposites was in good agreement with the McCullough model indicating the interfacial interaction developed in rubber nanocomposites. The enhanced optical properties, dielectric constant, thermal stability and electrical conductivity of Cl-NR/ZnFe2O4 systems enable the fabrication of highly-durable flexible electronic devices, actuators, super-capacitors and elastomeric pressure sensors.

Mechanistic insight into improving strength and stability of hydrogels via nano-silica

In this investigation, the nanocomposite hydrogels were prepared by hydrophilic nanoscale silica secondary crosslinking hydrolytic polyacrylamide (HPAM) hydrogel to improve its strength and stability performance. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to study the composition and microstructure of nanocomposite hydrogel. In addition, it increases the viscosity of the gel solution by increasing the amount of nano-silica. According to Sydansk coding system, the maximum gel strength of P (HPAM/HMAM/SiO2) hydrogel increased from code “F” to codes “G” and “H”. The stability time of P(HPAM/HMAM/SiO2) hydrogel increased from 30 days to 90 days. The results of molecular dynamics simulation (MDS) and differential scanning calorimetry analyses (DSC) showed that SiO2 increases the interactions between the water molecules and colloidal phase, which is the main reason for improving the stability of the nanocomposite hydrogel. The dehydration rate of hydrogel decreased with the increase of nanoparticle content in terms of the dehydration tests. The dehydration rate of hydrogel increases with the increase of temperature. In addition, the kinetics of all nanocomposite hydrogels dehydration can be described by first-order kinetics at 35 °C, 45 °C, and 55 °C.

Preparation, Characterization and Antibacterial activity of polyaniline-CdS nanocomposites

Polyaniline (PANI) semiconductor polymer and cadmium sulfide nanoparticles (CdS NPs) was prepared by chemical oxidation method and sol-gel method respectively. (10-40) wt% content of CdS NPs was added polyaniline conductive polymer powder to prepared PANI-CdS nanocomposites. The Fourier transform infrared analysis FT-IR spectra of the prepared samples revealed that the effective groups and peak locations referred to the confirming chemical bond are well-matched with the reported literature. The XRD results shows a very wide peak of PANi polymer which indicate to some crystallinity of PANi structure. Whereas the diffraction pattern of CdS NPs shows high crystallinity and polycrystalline nature of hexagonal wurtzite phase. The diffraction pattern of PANI-CdS nanocomposites shows lower peaks intensity than of CdS NPs and improved with the increase of CdS NPs content. The antibacterial activity of PANi and PANi-CdS nanocomposites was estimated by agar well diffusion method against four types of pathogenic bacteria Proteus mirabilis, Staphylococcus aureus, Escherichia coli and Klebsiella pneumonia. It was found that there is a strong antibacterial activity and the greatest effect was for the prepared PANi-CdS NPs 40 wt% and the highest activity was found against Staph. aureus bacteria as well as with the increase of nanoparticles content.

In-situ synthesized carboxymethyl chitosan/poly(vinyl alcohol) bio-nanocomposite hydrogels containing nanoparticles with drug-delivery properties

A drug-delivery approach was developed through effective preparation of bio-nanocomposite hydrogels in situ with ZnO/CuO/Ag nanoparticles being formed within swollen carboxymethyl chitosan (CMCh)/poly(vinyl alcohol) (PVA) hydrogels. Different experimental techniques, including Fourier transform-infrared, X-ray diffraction (XRD), energy-dispersive X-ray (EDX) analysis, and scanning electron microscopy (SEM) were applied to study and compare the prepared hydrogels. XRD and EDX analyses confirmed the formation of nanoparticles in the hydrogel matrix, while SEM micrographs showed that ZnO, CuO and Ag nanoparticles ranged from 36.26 to 76.09 nm, 34.15–71.71 nm and 36.21–78.47 nm within the same matrix, respectively. According to the results, an increased number of nanoparticles resulted from increased ion concentration. At pH 2.1 and pH 7.4, the bio-nanocomposite hydrogels were investigated in terms of the swelling behaviour; in comparison with neat CMCh/PVA hydrogel, they showed a pH-sensitive swelling ratio. As an in-vitro drug release test, the bio-nanocomposite hydrogels were applied to sustained and controlled drug-delivery system that increased with the increase in nanoparticles content that could result in protracted release of the ibuprofen.

Study on Biodegradable Chitosan-Whey Protein-Based Film Containing Bionanocomposite TiO2 and Zataria multiflora Essential Oil

In our research, a composite film of whey protein isolate (WPI)/chitosan incorporated with TiO2 nanoparticles (NPs) and essential oil of Zataria multiflora (ZEO) was developed. The resulting composite films were evaluated by FTIR, SEM, and XRD, and also the physicochemical characteristics including color, mechanical properties, swelling ratio, and water vapor permeability (WVP) were studied. SEM graphs exhibited that the samples had a uniform and homogeneous structure where TiO2 NPs and ZEO were well dispersed. FTIR and XRD findings also show that the hydrogen bonds and hydrophobic interactions are the main interactions between the composite WPI/chitosan and TiO2. The crystalline nature of the composite samples increased with the increase of NP content. Nevertheless, ZEO had an insignificant effect on the functional groups and the crystallinity of composite samples. The film visual characterization revealed that, by adding and increasing the TiO2 and TiO2-ZEO, sample lightness and opacity significantly increased. Additions of TiO2 remarkably (p<0.05) improved the water vapor and mechanical properties of composite samples, although the loading of ZEO, regardless of TiO2 incorporation, led to a considerable decrement of these properties. Furthermore, composite films containing ZEO combined with 2% of TiO2 compared with 1% of NPs blended with ZEO had strong antimicrobial properties against Staphylococcus aureus, Escherichia coli, and Listeria monocytogenes. Generally, the findings proposed that the addition of TiO2 reinforces the properties of composite films with a synergistic effect of ZEO loading on the antibacterial ability, by which the resulting biodegradable composite samples can be used as a food active packaging material.

Effect of Nanoparticles Concentration on Thermal, Magnetic and Electrical Properties of Ni0.5Zn0.5Fe2O4 based Polyaniline Nanocomposites by In-Situ Polymerisation

Polyaniline– Ni0.5Zn0.5Fe2O4 nanocomposites were prepared via in-situ polymerization of aniline using Ni0.5Zn0.5Fe2O4 nanoparticles varying their percentage in aniline from 0% to 100% (w/w). These nanocomposites have been characterized by XRD, FTIR, high-resolution TEM, room temperature VSM and TGA. TEM images suggests that the nanoparticles are rooted in the polyaniline matrix and chain like structure of the composites for higher polyaniline concentration. It is revealed that magnetic and thermal properties of these nanocomposites increases with increase in nanoparticles content. The synergetic effect of super paramagnetic nickel zinc ferrite can make polyaniline nanocomposites magneto-responsive The effect of loading of nanoparticles on AC conductivity and impedance in the frequency range of 100 Hz to 100 MHz and DC conductivity were thoroughly studied. The conductivity of nanocomposites was found to be improved than pure polyaniline up to 10% loading. The investigations revealed that magnetic and electronic properties of nanocomposites can be tailored by Ni0.5Zn0.5Fe2O4 content.

Dimensionality and superconducting parameters of YBa2Cu3O7−d/(WO3 NPs)x composites deduced from excess conductivity analysis

Superconducting composite products of type YBa2Cu3O7−d (noted Y-123) added with different contents (x wt.%) of tungsten oxide nanoparticles (WO3 NPs), x = 0.0–1.0 wt%, were produced via the standard solid-state reaction technique. Samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrical resistivity measurements. XRD examination showed that the Y-123 orthorhombic structure is not altered by WO3 NPs additions. SEM observations indicated a reduction in the grains size with the increase of nanoparticles content. The investigation of the excess conductivity of different prepared composites was analyzed using Aslamazov-Larkin (AL) model. The investigated samples comprised of five distinct fluctuation regimes, namely short-wave (SWF), one-dimensional (1D), two-dimensional (2D), three-dimensional (3D), and critical (CR) fluctuations regimes. The coherence length along c-axis at zero-temperature (ξc(0)), lower and upper critical magnetic fields (Bc1 and Bc2), critical current density (Jc) and numerous other superconducting parameters were estimated with respect to WO3 NPs content. Compared to undoped Y-123 sample, it was found that an amount of x = 0.05 wt% of WO3 NPs is appropriate to improve the physical performances of Y-123, whereas with further increasing x, these performances were weakened.

Investigation of triplex CaAl2ZnO5 nanocrystals on electrical permittivity, optical and structural characteristics of PVA nanocomposite films

Nanocomposite (NC) films of polyvinyl alcohol (PVA)/calcium aluminum-doped zincate (CaAl2ZnO5) have been fabricated with varying amounts, namely 2, 4, 6 and 8 wt% of CaAl2ZnO5 nanoparticles (NPs) by solution casting technique. TEM data showed that an average particle size of CaAl2ZnO5 NPs is ~ 25 nm. The effect of CaAl2ZnO5 content on structural and morphological behaviors has been established by Fourier-transform infrared spectroscopy and scanning electron microscopy, respectively. The photo-response of NCs was derived by UV–visible spectroscopy where the band gap energy (Eg) reduced from 5.25 eV for PVA to 2.82 eV for PVA/8 wt% CaAl2ZnO5 NC film. The dielectric permittivity and current–voltage (I–V) characteristics were studied using LCR—meter in frequency range of 50 Hz–5000 kHz. The relative dielectric constant (e′) was increased from 15 to 65 with increase in NPs content from 0 to 8 wt%. The PVA NC with 8 wt% CaAl2ZnO5NPs raises the ac conductivity to 3.35 × 10−5 S cm−1 at room temperature. The cyclic voltammetry (CV) tests have been performed to calculate the specific capacitance of the NCs as a positive electrode against Ag/AgCl as reference electrode. The specific capacitance increases from 1. Fg−1 for PVA to 3.69 Fg−1 for PVA/8 wt% CaAl2ZnO5 NC. These behaviors will support the possible applications in optical display devices and micro-electrical and electronic applications.

In-situ synthesis of silica aerogel/polyurethane inorganic-organic hybrid nanocomposite foams: Characterization, cell microstructure and mechanical properties

Silica aerogel nanoparticles have various applications due to their unique properties such as low thermal conductivity, high specific surface area as well as low density. However, due to low mechanical properties of pure silica aerogel, its composite with other materials is used as thermal insulators. In this work, hydrophobic silica aerogel was synthesized using sol-gel as well as solvent substitution methods, and calcined at 200, 300, 400 and 500 °C. In order to improve the mechanical properties, nanocomposites of hydrophobic silica aerogel and polyurethane with 0.5, 1, 3 and 5 wt% of nanoparticle content were prepared. Nanocomposite foams of polyurethane/silica aerogel were prepared with two separate methods: mixing silica aerogel in polyol and mixing those in diisocyanate. Cyclopentane was used as foaming agent. Results of FESEM, BET and water contact angle analysis showed that silica aerogel nanoparticles possess high specific surface area. Furthermore, the calcined particles at 500 °C showed hydrophilic properties. Optical microscopy Images showed that the sample containing 1 wt% of nanoparticles has the lowest cell diameter, highest cell density and narrower cell size distribution due to higher cell nucleation and homogeneity. Moreover, with the increase in nanoparticle content, the cell size distribution was broadened and cell density decreased. Results of scanning electron microscopy (SEM) analysis confirmed that lower contents of hydrophilic nanoparticles in both mixing media leads to more homogeneous and uniform cell microstructure. Results of compression tests showed that in samples with lower cell size and homogenous cell microstructure, the resistance against compression increased and the mechanical properties improved, this was clearly evident in nanocomposite foam containing 1 wt% of silica aerogel.

Mechanistic study of energy dependent scattering and hole-phonon interaction at hybrid polymer composite interfaces for optimized thermoelectric performance

Low energy barriers for charge transport may improve thermoelectric performance in heterostructured inorganic materials and hybrid polymer composites. In this study, earth abundant Cu12Sb4S13 nanoparticles were synthesized and incorporated into poly (3,4-ethylenedioxythiophene) (PEDOT) matrices. The surface of nanoparticles was modified with ligands that improve carrier transport while maintaining the Seebeck coefficient. We demonstrated optimized thermoelectric figures of merit, ZT, were obtained at around 5 wt.% nanoparticle content, which we attribute to a low hole-phonon interaction, an effective phonon scattering, and mainly to the presence of a proper density of low energy barriers, 0.17 eV, between the energy states of Cu12Sb4S13 nanoparticle and PEDOT nanofiber and which selectively scatter low energy charge carriers. A 2.5-fold increase of ZT over pristine PEDOT nanofiber, ZT = 0.0098, was obtained by polymer composite at the optimal nanoparticle concentration. Remarkably, electrical conductivity and Seebeck coefficient decreased with an increase in nanoparticle content beyond 5 wt.%, which is attributed to the non-energy dependent hole-phonon interaction. These findings are expected to create an economical and new route for enhancing ZT in hybrid thermoelectric polymer composite and devices.

Characterization of a green nanocomposite prepared from soluble soy bean polysaccharide/Cloisite 30B and evaluation of its toxicity

The present paper aims to elucidate the structural, thermal and mechanical properties of soybean polysaccharide (SSPS)/Cloisite 30B. Tensile strength of the nanocomposite films improved with incorporation of nanoparticles, whereas elongation at break decreased. Surface roughness of the samples increased with the addition of nanoclay. Neat SSPS film and SSPS-1% Cloisite 30B had a relatively smooth surface with no irregularities, while for the samples containing 3 and 7% Cloisite 30B, the surface was rough. DSC analysis demonstrated that following an increase in nanoparticles content, the melting temperature of the nanocomposite elevated, whereas, glass transition temperature decreased. The results of antibacterial activity indicated that Cloisite 30B could inhibit the growth of Salmonella typhi PTCC 1609, Staphylococcus epidermis PTCC 1114 (ATCC 12228) and Listeria monocytogenes PTCC 1165. SSPS-Cloisite 30B nanocomposite could not inhibit the growth of Aspergillus niger. The results demonstrated that the migration of nanoparticles might happen into deionized water as a food simulant, but they could not migrate into bread as a food model. Furthermore, it was found that Cloisite 30B nanoparticles had cytotoxicity effect, and thus, it is recommended that Cloisite 30B/SSPS nanocomposites be used only for the packaging of solids foods such as bread.

Influence of copper sulphide nanoparticles on the structural, mechanical and dielectric properties of poly(vinyl alcohol)/poly(vinyl pyrrolidone) blend nanocomposites

Blend nanocomposites based on poly(vinyl alcohol) (PVA)/poly(vinyl pyrrolidone) (PVP) with varying content of copper sulphide (CuS) nanoparticles have been prepared by employing a green solvent casting strategy. The interaction of blend components has been assessed by using Fourier transform infrared and UV–Vis spectroscopy, scanning electron microscopy (SEM), transition electron microscopy (TEM), X-ray diffraction, thermogravimetric analysis (TGA) and differential scanning calorimetry. The spectroscopic studies have revealed the existence of strong interface interaction between the blend components as well as CuS nanoparticles. The addition of CuS nanoparticles to PVA/PVP blend has been enhancing the semi-crystalline nature of the blend. The uniform dispersion of CuS nanoparticles in the blend has been ensured by the morphology revealed through the SEM and TEM. The glass transition temperature of the composite has been found to be increasing with increase in the content of CuS revealing the ordered arrangement of nanoparticles in the blend. The excellent thermal stability of the blend nanocomposite compared to pure PVA/PVP blend and its improvement with the loading of CuS nanoparticles has been proved by TGA. The mechanical properties, electrical conductivity and dielectric behavior of the bio-degradable nanocomposites were also studied. The dielectric properties, AC and DC conductivity of the nanocomposites were significantly increased with increase in content of nanoparticles. Mechanical properties such as tensile strength and hardness of the nanocomposite have showed an increasing trend with the loading of CuS nanoparticles. The AC conductivity and dielectric properties of the blend composites have registered an increase with the loading of nanoparticles up to 10 wt% concentration.

In situ synthesis, characterization, conductivity studies of polypyrrole/silver doped zinc oxide nanocomposites and their application for ammonia gas sensing

The synthesis of polypyrrole (PPy)/silver doped zinc oxide (Ag–ZnO) nanocomposites have been carried out by employing a simple and environmentally benign in situ polymerisation strategy. The structural, morphological and thermal properties of nanocomposites were characterised through Fourier transform infrared spectra (FTIR), X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The FTIR spectra revealed the formation of nanocomposite by the shift in the characteristic peak of PPy to a lower wavenumber region in PPy/Ag–ZnO nanocomposite. The effective utilisation of the surface of the Ag–ZnO nanoparticles by PPy chains was also confirmed from X-ray diffraction. The SEM and TEM images revealed the good interaction between Ag–ZnO and PPy up to a loading of 10 weight percentage (wt%). TGA studies indicated the excellent thermal stability of the polymer nanocomposite. DSC results revealed that the glass transition temperature of the nanocomposite was increased with increase in the concentration of nanoparticles. The electrical properties of the nanocomposites were studied from the direct current (DC) and alternating current (AC) resistivity measurements. The dielectric properties, AC and DC conductivity of the nanocomposites were significantly increased with increase in content of nanoparticles. The sensitivity of ammonia gas through the nanocomposites was also evaluated with respect to different contents of nanoparticles. The ammonia sensing properties of nanocomposite was higher than that of pure PPy and the maximum sensor response was observed for 10 wt% of composite.

Influence of Alpha Nanoalumina Reinforcement Content on the Microstructure, Mechanical and Corrosion Properties of Al6061-Al2O3 Composite

Sol–gel prepared nanoparticles of alpha alumina were mixed in their varying weight percentage (0.5, 1, 1.5, 2 and 2.5 wt.%) with Al-6061 powder for synthesizing of Al6061-Al2O3 nanocomposites using powder metallurgy route. After sintering at 610 °C, microstructural, mechanical and corrosion properties of the composite samples were evaluated to see the effect of nanoalumina reinforcement content on these properties. Microstructural examination of the composites indicated the uniform distribution of nanoparticles up to their 2 wt.% content. Above this amount, distribution of nanoparticle attained saturation level and their accumulation started in the grain boundary regions. It is found that by increasing the nanoparticles content, the hardness and strength first increase and then decrease when amount of nanoparticle exceeds 2 wt.%. Reinforcement of 0.5-1 wt.% nanoparticle content has shown excellent corrosion resistance of the synthesized composites in 3.5% NaCl solution. After 1 wt.% incorporation of nanoparticles, a gradual increase in corrosion rate with the increase in nanoparticle content was measured and corrosion becomes worse than that of the base alloy in the presence of 2.5 wt.% nanoparticle content. Solution heat treatment followed by ageing of the composite samples was found highly beneficial for the increase in hardness.

Synthesis, characterization, material properties and sensor application study of polyaniline/niobium doped titanium dioxide nanocomposites

Conducting polyaniline (PANI)/niobium doped titanium dioxide (Nb–TiO2) nanocomposites with different weight percentages of Nb–TiO2 nanoparticles were synthesized by an in situ polymerization method. The synthesized materials were characterized by FT-IR, UV, XRD, SEM, HRTEM, TGA, DSC and electrical conductivity measurements. Also, the ammonia gas sensing properties of PANI and its nanocomposites have been explored thoroughly. The FT-IR and UV spectra showed the clear evidences for the presence of nanoparticles by shifting to a broad peak, which indicates the interaction of nanoparticles with PANI. The XRD study reveals the crystalline nature of the fabricated nanocomposite. SEM and TEM analysis indicates the uniform dispersion of nanoparticles in the polymer matrix with spherically shaped particles having the nano-size region. TGA analysis showed the increased thermal stability of nanocomposites with an increase in concentration of nanoparticles. The increase in glass transition and melting temperature with the increase in content of nanoparticles were obtained from DSC. Both AC and DC conductivity and dielectric properties of the nanocomposites were increased with the increase in content of nanoparticles and the maximum electrical properties were obtained for 10 wt% of composite. The fabricated composites showed excellent sensitivity and fast response to ammonia gas at room temperature. The effect of nanoparticles in the polymer chain increases the potential application of the conducting polyaniline, can act as multifunctional promising new material such as nanoelectronic devices and sensors.

Effect of different nanoparticles on tuning electrical properties of polypropylene nanocomposites

Polypropylene (PP) has shown great potential as recyclable HVDC cable insulation material. This paper aims to investigate the effect of different nanoparticles on tuning the electrical properties of PP. Surface modified MgO, TiO 2 , ZnO and Al 2 O 3 nanoparticles with various contents were melt blended with PP. The microstructural morphology, dielectric properties, DC volume resistivity, space charge behavior and DC breakdown strength of the nanocomposites were investigated. It was found that the dielectric permittivity all increases with the increase of nanoparticle content, only the dielectric loss of TiO 2 /PP nanocomposites increases. For MgO and TiO 2 nanocomposites, the DC volume resistivity increases with the increase of nanoparticle content and then decreases, while it continues to increase for Al 2 O 3 nanocomposite. TiO 2 /PP nanocomposite with 5 phr nano-TiO 2 shows lower volume resistivity than PP. Space charge suppression and DC electric breakdown strength show similar variation trend, both increase with the increase of nanoparticle content and then decrease. MgO and TiO 2 nanocomposites show the most obvious space charge suppression and TiO 2 nanocomposites exhibit the highest DC breakdown strength, which is 43% higher than that of pure PP. Considering the electrical properties investigated, the optimal content for MgO, TiO 2 , ZnO and Al 2 O 3 nanoparticles is about 3, 1, 1 and 1 phr, respectively. Among these four kinds of nanoparticles, MgO and TiO2 nanoparticles are more capable than ZnO and Al 2 O 3 nanoparticles to modify the electrical properties of PP and more potential to be used as recyclable HVDC cable insulation material.

Experimental Study on Influence of Trap Parameters on Dielectric Characteristics of Nano-Modified Insulation Pressboard.

In order to study the influence of trap parameters on dielectric characteristics of nano-modified pressboards, pressboards were made using the nano doping method with different nanoparticle components. The dielectric characteristics of the modified pressboards were measured, and the trap parameters were investigated using the thermally stimulated current (TSC) method. The test results indicated that the conductivity initially declined and then rose with the increase of nano-Al2O3 content, whereas it solely rose with the increase of nano-SiC content. Moreover, the conductivity exhibited nonlinear characteristics with the enhancement of electric field stress at high nanoparticle content. The relative permittivity of modified pressboard declines initially and then rises with the increase of nanoparticle content. In addition, the breakdown strength of modified pressboards exhibited a pattern of incline followed by decline with the increase of nano-Al2O3 content, while it always declined with the increase of nano-SiC content. The analysis based on the energy band theory on trap parameters of the constructed multi-core model concludes that the nanoparticle components added in pressboard altered both the depth and density of traps. It is therefore concluded that trap parameters have significant influence on the dielectric characteristics of nano-modified insulation pressboard.