Biomass fly ash as nanofiller to improve the dielectric properties of low-density polyethylene for possible high-voltage applications.

Flexible capacitive energy storage applications require polymer nanocomposites with high dielectric properties, which can be accomplished by addition of inorganic nanofillers to the polymer matrix. Low-density polyethylene (LDPE), known for its good dielectric characteristics and wide use in electrical insulation have been investigated for the desired applications. However, the improvement of its breakdown strength still continues with the use of various nanomaterials employed as nanofillers. In this study, a waste-derived material known as biomass fly ash (BFA) as a nanofiller to improve the dielectric properties of LDPE has been explored. BFA exhibits versatility in its composition with various metal oxides, making it an attractive choice as a nanofiller. The BFA-LDPE sheets were prepared using a conventional solvent mixing and subsequent hot-pressing process, incorporating BFA loadings ranging from 1 % to 4 wt%. The effects of different BFA loadings were carefully examined, and the synthesized nanocomposites were extensively characterized using various characterization methods, such as XRD, SEM, FTIR, TGA and dielectric constant measurements, to investigate the crystallographic properties, morphology, chemical composition, and thermal stability. Among all the nanocomposites, 4 wt%BFA-LDPE exhibited the highest dielectric constant, with a value of 11.58, compared to simple LDPE that had a dielectric constant of 8.33. This improvement is ascribed to the synergistic effects of different inorganic metal oxides (SiO2, MgO, and Fe2O3) present in BFA. The results showed a significant enhancement in dielectric properties, indicating that the waste-derived BFA can be purposefully applied as an effective nanofiller in the LDPE-based composites with even less than 4% loading for electrical insulating applications in future studies.

Phenol-Furfural Resin/Graphite/Ag-Based Electrically Conductive Adhesive Composites from Waste Bagasse with Enhanced Thermo-Electric Properties.

This study describes the preparation and evaluation of phenol-furfural resin (PFR) from bagasse and its nanocomposites for electrically conductive adhesive (ECA) application. PFR was prepared with furfural extracted from bagasse using a modified acid digestion method. Three different formulations of PFR nanocomposites with conductive nanoparticles, i.e., PFR-silver, PFR-graphite, and PFR-silver + graphite, were prepared using 20, 40, and 60 w/w% of fillers via the impregnation method. The resultant products were characterized using FT-IR, SEM, EDS, and XRD spectroscopy. Electrical conductivity was measured using a four-probe technique, while band gap was calculated via Tauc plots. The results exhibited a significant rise in electrical conductivity of insulating virgin PFR from 2.6 × 10-4 Scm-1 to 8.2 × 10-1 Scm-1 with a 40 and 20 w/w% blend of Ag and graphite in PFR. This synergism was exhibited because graphite and Ag NPs supply excellent junctions for building networks. Both tend to coalesce due to van der Waals forces and high surface energies. Therefore, conductive pathway numbers can be increased, and the contact area can be effectively enlarged. This ternary composite exhibited the lowest bandgap energy value, i.e., 3.1 eV. Thermogravimetric temperature values T0 and Tdeg were increased up to 120 °C and 484 °C, respectively, showing a significant increase in thermal stability. Therefore, the resultant nanocomposite material has good potential to be employed as an ECA in the electronic industry.

Improved PVC/ZnO Nanocomposite Insulation for High Voltage and High Temperature Applications.

Nanosized inorganic oxides have the trends to improve many characteristics of solid polymer insulation. In this work, the characteristics of improved poly (vinyl chloride) (PVC)/ZnO are evaluated using 0, 2, 4 and 6 phr of ZnO nanoparticles dispersed in polymer matrix using internal mixer and finally compressed into circular disk with 80 mm diameter using compression molding technique. Dispersion properties are studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and optical microscopy (OM). The effect of filler on the electrical, optical, thermal, and dielectric properties of the PVC are also analyzed. Hydrophobicity of nano-composites is evaluated by measuring contact angle and recording hydrophobicity class using Swedish transmission research institute (STRI) classification method. Hydrophobic behavior decreases with the increase in filler content; contact angle increases up to 86°, and STRI class of HC3 for PZ4 is observed. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are employed to evaluate the thermal properties of the samples. Also, continuous decrease of optical band gap energy from 4.04 eV for PZ0 to 2.57 eV for PZ6 is observed. In the meantime, an enhancement in the melting temperature, Tm, is observed from 172 to 215 °C. To check the stability of materials against hydrothermal stresses, all the fabricated materials are then subjected to a hydrothermal aging process for 1000 h and their structural stability is analyzed using optical microscopy and FTIR analyses.

Development and Investigation of High Performance PVA/NiO and PVA/CuO Nanocomposites with Improved Physical, Dielectric and Mechanical Properties.

A series of polyvinyl alcohol (PVA)based composites with well dispersed nano fillers were fabricated and compared in terms of dielectric, mechanical, and optical properties. Specifically, NiO and CuO nano-fillers were utilized in a range of 0.2-0.6 wt% for thin film fabrication by solution deposition method. The characterization of nanocomposites was confirmed through FTIR, FESEM, and XRPD, whereas dielectric and mechanical properties were analyzed with respect to the filler concentrations. The bandgap of PVA/nano-filler composites reduced with an increase in NiO and CuO concentration from 0.2 to 0.6 wt%. The increase in the permittivity of the material was observed for 6 wt% of nano-fillers. The toughness of PVA/nano-filler composites was improved by increasing CuO and NiO concentration and Young's modulus of 30.9 and 27.2 MPa for 0.6 wt% of NiO and CuO-based nanocomposite, respectively, was observed. The addition of nano-fillers showed improved optical, dielectric, and mechanical properties.

A Sequenced Study of Improved Dielectric Properties of Carbon Nanotubes and Metal Oxide-Reinforced Polymer Composites.

Polymers have gained attraction at the industrial level owing to their elastic and lightweight nature, as well as their astonishing mechanical and electrical applications. Their scope is limited due to their organic nature, which eventually leads to the degradation of their properties. The aim of this work was to produce polymer composites with finely dispersed metal oxide nanofillers and carbon nanotubes (CNTs) for the investigation of their charge-storage applications. This work reports the preparation of different polymeric composites with varying concentrations of metal oxide (MO) nanofillers and single-walled carbon nanotubes (SWCNTs). The successful synthesis of nanofillers (i.e., NiO and CuO) was carried out via the sonication and precipitation methods, respectively. After, the smooth and uniform polymeric composite thin films were prepared via the solution-casting methodology. Spectroscopy and diffraction techniques were used for the preliminary characterization. Scanning electron microscopy was used to check the dispersion of carbon nanotubes (CNTs) and MOs in the polymer matrix. The addition of nanofillers and carbon nanotubes (CNTs) tuned the bandgap, reduced the strain, and enhanced the elastic limit of the polymer. The addition of CNT enhanced the mechanical strength of the composite; however, it increased the conductivity, which was tuned by using metal oxides. By increasing the concentration of NiO and CuO from 2% to 6% bandgap of PVA, which is 5-6 eV reduced to 4.41 and 4.34 eV, Young's moduli of up to 59 and 57.7 MPa, respectively, were achieved. Moreover, improved dielectric properties were achieved, which shows that the addition of metal oxide enhances the dielectric behavior of the material.

Investigation of Ramped Compression Effect on the Dielectric Properties of Silicone Rubber Composites for the Coating of High-Voltage Insulation.

The incorporation of inorganic oxide fillers imparts superior dielectric properties in silicone rubber for high-voltage insulation. However, the dielectric characteristics are influenced by the mechanical stress. The effects of ramped compression on the dielectric properties of neat silicone rubber (NSiR), 15% SiO2 microcomposite (SSMC), 15% alumina trihydrate (ATH) microcomposite (SAMC) and 10% ATH + 2% SiO2 hybrid composite (SMNC) are presented in this study. The dielectric constant and dissipation factor were measured before and after each compression especially in the frequency range of 50 kHz to 2MHz. Before the compression, SSMC expressed the highest dielectric constant of 4.44 followed by SMNC and SAMC. After the compression cycle, SAMC expressed a better dielectric behavior exhibiting dielectric constant of 7.19 and a dissipation factor of 0.01164. Overall, SAMC expressed better dielectric response before and after compression cycle with dielectric constant and dissipation factor in admissible ranges.

Degradation Performance Investigation of Hydrothermally Stressed Epoxy Micro and Nanocomposites for High Voltage Insulation.

Epoxy resins have demonstrated remarkable properties with potential for usage as high voltage insulators. However, a loss of these properties has been observed in high temperature and humid environments. In order to enhance the hydrothermal stability of epoxy resins, micro (15% SiO2) and nano (5% SiO2) silica-based composites of epoxy were fabricated and subjected to standard long term and short term accelerated hydrothermal conditions. To analyze the effect of these stresses, the samples were analyzed periodically through Fourier transform infrared spectroscopy (FTIR) for structure analysis; scanning electron microscopy (SEM) for surface analysis of long-term aged samples; and optical microscopy for the surface topography of short-term aged samples. The Swedish Transmission Research Institute (STRI) classification and contact angle measurement techniques were used for hydrophobicity analysis of long-term and short-term aged samples, respectively. After aging in both conditions, the nanocomposite showed better results as compared to the other samples. After 1000 h of aging, it showed HC-5 class of hydrophobicity, whereas EMC and NE degraded to the HC-6. In case of short-term aging, the contact angle decreased to the 64.15° and 75.05° from 104.15° and 114.9° for ENC and EMC, respectively. Also, in terms of structural degradation, ENC showed the highest structural stability after 1000 h of aging with the highest stable peak of aromatic ether at 1300-1500 cm-1. Microscopic observation through scanning electron and optical techniques also revealed superior performance of the nanocomposites.

Surface Recovery Investigation of Silicone Rubber Composites for Outdoor Electrical Insulation under Accelerated Temperature and Humidity.

Degradation of silicon rubber due to heat and humidity affect its performance in outdoor applications. To analyze the effects of high temperature and humidity on room temperature vulcanized (RTV) silicone rubber (SiR) and its composites, this study was performed. Five different sample compositions including neat silicone rubber (nSiR), microcomposites (15 wt% silica(SMC 15% SiO2) and 15 wt% ATH(SMC 15% ATH), nanocomposite (2.5 wt% silica(SNC 2.5% SiO2) and hybrid composite (10 wt% micro alumina trihydrate with 2 wt% nano silica(SMNC 10% ATH 2% SiO2) were prepared and subjected to 70 ˚C temperature and 80% relative humidity in an environmental chamber for 120 h. Contact angle, optical microscopy and Fourier transform infrared (FTIR) spectroscopy were employed to analyze the recovery properties before and after applying stresses. Different trends of degradation and recovery were observed for different concentrations of composites. Addition of fillers improved the overall performance of composites and SMC 15% ATH composite performed better than other composites. For high temperature and humidity, the ATH-based microcomposite was recommended over silica due to its superior thermal retardation properties of ATH. It has been proved that ATH filler is able to withstand high temperature and humidity.

Influence of Ramped Compression on the Dielectric Behavior of the High-Voltage Epoxy Composites.

The emergence of micro and nano-based inorganic oxide fillers with optimal filler-loadings further enhances the required insulation characteristics of neat epoxy. During manufacturing and service application, insulators and dielectrics face mechanical stresses which may alter their basic characteristics. Keeping this in mind, the facts' influence of mechanical stresses and fillers on dielectric properties of polymeric insulators of two epoxy/silica composites were fabricated and thoroughly analyzed for dielectric characteristics under ramped mechanical compressions relative to the unfilled sample. Before compression, epoxy nanocomposites exhibited responses having an average dielectric constant of 7.68 with an average dissipation factor of 0.18. After each compression, dielectric properties of all samples were analyzed. The dissipation factor and the dielectric constant trends of each sample are plotted against a suitable frequency range. It was observed that after the successive compressions up to 25 MPa, the dielectric properties of epoxy micro-silica composites were highly affected, having an average final dielectric constant of 9.65 times that of the uncompressed sample and a dissipation factor of 2.2 times that of the uncompressed sample, and these were recorded.

Investigation of Hydrothermally Stressed Silicone Rubber/Silica Micro and Nanocomposite for the Coating High Voltage Insulation Applications.

Silicone rubber is a promising insulating material that has been performing well for different insulating and dielectric applications. However, in outdoor applications, environmental stresses cause structural and surface degradations that diminish its insulating properties. This effect of degradation can be reduced with the addition of a suitable filler to the polymer chains. For the investigation of structural changes and hydrophobicity four different systems were fabricated, including neat silicone rubber, a micro composite (with 15% micro-silica filler), and nanocomposites (with 2.5% and 5% nanosilica filler) by subjecting them to various hydrothermal conditions. In general, remarkable results were obtained by the addition of fillers. However, nanocomposites showed the best resistance against the applied stresses. In comparison to neat silicone rubber, the stability of the structure and hydrophobic behavior was better for micro-silica, which was further enhanced in the case of nanocomposites. The inclusion of 5% nanosilica showed the best results before and after applying aging conditions.

Multi-Stressed Nano and Micro-Silica/Silicone Rubber Composites with Improved Dielectric and High-Voltage Insulation Properties.

The scope of silicone rubber (SiR) is confined due to the deprivation of its dielectric propertiesupon exposure to various ambient stresses. The aim of this research is to develop silicone rubber-based composites by employing inorganic oxide fillers for improved dielectric and high voltage insulation properties for widening its scope in the field of electrical appliances. This study reports the preparation of different composites of silicone rubber with varying concentrations of micro and nano-silica fillers. The dielectric propertytrends of these as-prepared neat and impregnated samples were examined via an indigenously developed weathering chamber capable of applying multiple stresses of acid rain, heat, humidity, UVA radiation, and salt fog. Dielectric constant values were measured before and after applying stresses. Upon applying stresses, a periodic decline in dielectric constant was observed. Improved dielectric properties were obtained by adding micro and nano-silica as fillers. A nano silica-incorporated silicone rubber product exhibited good potential for dual applications as dielectric and high voltage insulation.