Dielectric Applications Research Articles

Balancing the Mechanical Toughness and Electrical Insulation of Polypropylene by Blending and Grafting Modifications

AbstractBalancing the mechanical toughness and electrical insulation of polypropylene (PP) for recyclable cable insulation application has attracted increasing attention. Due to the different molecular conformation, isotactic polypropylene (IPP) always delivers excellent electrical insulation but poor mechanical toughness, while block polypropylene (BPP) has been dramatically opposed properties. Blending IPP with BPP at an appropriate content may be beneficial to reconcile the toughness and insulation. In this study, the blending ratio of IPP and BPP is first investigated, and it is found that 60: 40 wt.% is the optimized ratio for achieving outstanding overall performance. Furthermore, polyolefin elastomer (POE) and styrene‐grafted POE (POE‐g‐St) are incorporated into IPP/BPP blends respectively to intensify the toughness as well as the insulation property. The microstructure, electrical properties, mechanical properties, and thermal properties of the composites are systematically analyzed and discussed. The results demonstrate that the composite with a grafting ratio of 1.21 wt.% styrene exhibits superior overall performances, the enhanced breakdown field strength of 314.02 kV mm−1, and reduced elastic modulus of 352.54 MPa are achieved. Additionally, the modified composites also possess a high melting temperature, high volume resistivity, and excellent space charge suppression capability, achieving the synergistic improvements of the electrical, mechanical, and thermal properties.

Enhanced mechanical and thermal performance of Crosslinked Polyimides: Insights from molecular dynamics simulations and experimental characterization for motor insulation applications

Enhanced mechanical and thermal performance of Crosslinked Polyimides: Insights from molecular dynamics simulations and experimental characterization for motor insulation applications

Evaluation of mechanical and thermal performance of jute and coconut fiber-reinforced epoxy composites with rice husk ash for wall insulation applications

Evaluation of mechanical and thermal performance of jute and coconut fiber-reinforced epoxy composites with rice husk ash for wall insulation applications

High-strength polyurethane-reinforced glass fiber spacer fabric for cost-effective, lightweight, and high-temperature insulation applications

High-strength polyurethane-reinforced glass fiber spacer fabric for cost-effective, lightweight, and high-temperature insulation applications

Structure, Dielectric, and Thermal Behavior of Bismuth Titanate Nanoparticles

AbstractBismuth titanate (BTI) nanoparticles were synthesized via hydrothermal method. The XRD spectra show that the maximum intense peaks are associated to orthorhombic Bi4Ti3O12, and the pH did not show any significant effect on the structural transformation. The X‐ray photoelectron spectrum (XPS) of BTI nanoparticles clearly shows the presence of elements like Bi, Ti, and O. It is noticed that the grain size is increasing from 64.9 to 97.0 nm with an increase in pH from 9 to 12. The TEM images evidenced the presence of spherical nanoparticles. The bandgap values are decreased from 3.201 to 2.595 eV (for pH = 9–12). The absorption spectra established a fact that the maximum absorption wavelength is decreasing from 218–225 nm with an increase of pH from 9 to 12. In case of BTI of pH = 12, the loss is noted to be 153.201, providing the dielectric absorber applications at high frequency. The M′ versus M″ plots show the partial relaxations, indicating the existence of carriers of partial relaxation strength and exhibit the non‐Debye relaxations. The mass losses are increased for BTI samples till pH = 11, while the mass loss is decreased.

Recyclable Low Dielectric Polymers with High Thermal Conductivity for Copper‐Clad Laminated Film for High‐Frequency Applications

AbstractWith the rapid increase in demand for next‐generation communication, the development of advanced dielectric materials has become imperative. To enhance the performance and reliability of miniaturized electronic devices, dielectric materials must exhibit high thermal conductivity (λ) while simultaneously fulfilling crucial criteria such as low dielectric permittivity (Dk) and dielectric loss (Df). The synthesis of novel low dielectric polymers (LDPs) is newly reported by integrating fused aromatic mesogens and siloxane functions with silane linkers. Fused aromatic mesogenic building blocks undergo crosslinking via hydrosilylation with octavinylsilsesquioxane (OVS). The resulting LDPs exhibit excellent low dielectric properties (Dk of 1.79 and a Df of 0.004) along with a high λ (0.89 W m−1 K−1). The cold crystallization of LDPs governs their molecular packing structure, which controls electron alignment and phonon transfer. A comprehensive understanding of the interplay between molecular packing structure and thermal properties of LDPs allows for precise tuning of signal transmission and heat conduction in dielectric polymers. Furthermore, the reprocessable and recyclable nature of LDPs highlights their potential as highly effective and environmentally sustainable materials for advanced dielectric applications.

Partial discharge characteristics of thermally aged mineral oil and eco-friendly vegetable oil under uniform electric field

Partial discharge (PD) detection plays an important role in the life assessment of liquid insulation in transformers. This paper investigates on the PD activity and characteristics in thermally aged mineral oil and eco-friendly rice bran and Sesame oils. To simulate surface discharges, plane-plane electrode configuration with pressboard of 1mm and 3mm thickness was used. The phase resolved PD patterns of thermally aged rice bran oil, sesame oil and mineral oil with pressboard were recorded and analyzed. From the results it is observed that the inception voltage of eco-friendly vegetable oils is higher than mineral oil. Also vegetable oil shows better PD characteristics hence they can be used for high voltage insulation applications.

Elucidating Mesostructural Effects on Thermal Conductivity for Enhanced Insulation Applications.

Thermal management is a key link in improving energy utilization and preparing insulation materials with excellent performance is the core technological issue. Complex and irregular pore structures of insulation materials hinder the exploration of structure-property relationships and the further promotion of material performance. Ordered mesoporous silica (OMS) is a kind of porous material with ordered frameworks. This work elucidates the effects of ordered porous architecture on the thermal conductivity of mesoporous silica. Herein, two typical OMS, SBA-15 and SBA-16, characterized by well-defined porous structures with distinct spatial orientations are synthesized to study the relevance between structure and thermal conductivity. Compared to the 3D cubic mesoporous structure of SBA-16, the 2D hexagonal structure of SBA-15 exhibits anisotropic effects that restrict both solid and gaseous conduction, thereby providing better thermal insulating. Due to the influence of porosity, the thermal conductivity is found to decrease strongly with increasing pore size and decreasing wall thickness. Moreover, OMS composite aerogels with outstanding thermal insulation, mechanical performance, and hydrophobicity are fabricated through incorporating OMS into cellulose nanofibers (CNF). Consequently, this work contributes to a deeper understanding of heat transfer in OMS and provides an idea for designing OMS-based composite materials, thereby advancing their potential applications.

Theoretical Modelling, Experimental Testing and Simulation Analysis of Thermal Properties for Green Building-Insulation Materials

In this study, 45 alternative green materials for building walls were experimentally produced, utilizing renewable (epoxidized sesame oil), natural (clay), and waste (Seyitömer fly ash) resources. These materials were evaluated based on key technical properties such as mass, tensile-compressive strength, and thermal conductivity, all of which are essential for construction and insulation applications. Subsequently, theoretical modeling was conducted for the material coded SE45, which demonstrated the lowest thermal conductivity. Through mathematical calculations, the theoretical thermal conductivity value was determined with a deviation of +5.88%. Furthermore, 48 alternative scenarios were designed for three different building envelope types (internally insulated, externally insulated, and sandwich), using commonly used building insulation materials alongside the sesame oil-based green material with the lowest thermal conductivity (SE45). Energy performance evaluations were conducted by analyzing temperature distributions along the walls of all designed scenarios using ANSYS simulations under the climatic conditions of Ankara, Turkey.

The Synthesis and Spectroscopic Characterization of Structural Changes in Hydrophobic Silica Aerogels upon Encapsulation of the LCC ICCG Enzyme

Silica aerogels are highly porous materials known for their low density and extensive surface area, making them ideal for applications in thermal insulation, catalysis, and environmental remediation. This study investigates the structural changes of functionalized hydrophobic silica aerogels used as carriers of the LCC ICCG enzyme. The aerogels were synthesized using the sol-gel method, with trimethylethoxysilane (TMES) as a functionalizing agent to enhance hydrophobicity. The enzyme-encapsulated aerogels were characterized using hyperpolarized 129Xe NMR, 29Si NMR, nitrogen sorption analysis, TEM, contact angle measurements, and FT-IR spectroscopy to evaluate their structural and chemical properties. The results confirmed successful encapsulation of the enzyme, as indicated by changes in the pore structure and network morphology. These findings demonstrate that functionalized silica aerogels can effectively support LCC ICCG immobilization, offering a promising approach for plastic degradation applications.

Study on the Influence of Nanofiller Additives in Enhancing Electrical Insulation Performance and Thermal Properties of Biodegradable Oils for Electrical Insulation Applications

Study on the Influence of Nanofiller Additives in Enhancing Electrical Insulation Performance and Thermal Properties of Biodegradable Oils for Electrical Insulation Applications

Glass Fiber-Reinforced Polypropylene Composites with High Solar Reflectance for Thermal Insulation Applications

Reflective thermal insulation layers can offer an energy-efficient strategy for preventing temperature rises by reflecting sunlight on surfaces. Our previous study presented a novel solvent-based method to prepare porous polypropylene (PP) with high solar reflectivity. However, the stiffness and strength of the neat porous PP were insufficient for thermal insulation applications, as mechanical loads from installation and environmental factors limit the applicability of such products. This paper addresses this gap by applying our solvent-based surface modification technology to glass fiber (GF)-reinforced PP composite sheets, creating a previously unexplored system. While the enhanced modulus and strength aligned with expectations, the micro- and nano-structured porous outer layers situated below the skin layer of the sheets, the refractive index mismatch between the PP matrix and the GF, and the size of the GF delivered a notable advancement in reflective thermal insulation performance. The combined effect of 30 wt% GF, nucleating agents, and surface modification resulted in a highly porous surface layer featuring spherulite sizes of 0.5–2.0 μm. With these combined effects, we achieved a modulus value of ~4 GPa, a tensile strength of 60 MPa, and an average solar reflectance of up to 94%. Thermal insulation performance measurements demonstrated that the registered inner temperature was lower by 24.1 °C compared to neat PP sheets. These combined effects demonstrate the potential of our solvent-based surface modification technology to develop cost-effective, porous PP composite sheets for efficient reflective thermal insulation.

OPTIMIZATION OF NON-ACOUSTIC PARAMETERS OF FIBROUS MATERIALS USING BIOLOGICALLY INSPIRED ALGORITHMS

This paper deals with the optimization of the acoustic properties of samples made of fibrous materials, using biologically inspired algorithms. Samples with a thickness of 10 mm were tested, and the results showed that cotton fibers bonded with polyurethane resin have excellent absorption properties in a wide frequency range. GWO, BW and Puma were used for optimization. The optimization results showed significant improvements in the acoustic properties of the material, opening up possibilities for further application in sound insulation and other relevant areas.

Ultralight and Flexible Subnanowire Aerogels for Intrinsically Hydrophobic Thermal Insulation.

Aerogels are regarded as the next generation of thermal insulators; however, conventional aerogels suffer from issues such as brittleness, low moisture resistance, and a complex production process. Subnanowires (SNWs) are emerging materials known for their exceptional flexibility, toughness, intrinsic hydrophobicity, and gelling capabilities, making them ideal building blocks for flexible, tough, hydrophobic, and thermally insulating aerogels. Herein, we present a simple and scalable strategy to construct SNW aerogels by freeze-drying hydroxyapatite (HAP) SNW dispersions in cyclohexane. The resulting aerogels consist of three-dimensional porous flakes composed of thin layers of SNW bundles. They exhibit numerous outstanding properties, including ultralow density (12.33 mg·cm-3), high porosity (99.15%), remarkable flexibility and toughness, and excellent thermal insulation properties (27.53 mW·m-1·K-1). Because the HAP SNWs consist of hydroxyapatite cores capped with hydrocarbon chains, the aerogels demonstrate intrinsic hydrophobicity (138° water contact angle) and superior thermal stability compared to polymer foams. Furthermore, the HAP SNW aerogels can effectively shield against infrared radiation due to their low thermal conductivity. This work suggests that SNWs can serve as superior building blocks for flexible, tough, and intrinsically hydrophobic aerogels, paving the way for future applications in thermal insulation.

Enhancement of mechanical and thermal properties of porous alkaline cements using silica and alumina nanoparticles

This study explores incorporation of silica- and alumina-bearing nanoparticles on the mechanical and physical properties of porous alkaline cements derived from industrial by-products. The aim was to determine if nanoparticles could enhance thermal performance, increasing porosity while maintaining compressive strengthSi nanoparticles enhanced strength, up to 100%, attributed to the combination of Si nanoparticles with the aluminosilicate gel. Al nanoparticles did not enhance mechanical performance, but led to density reduction, resulting in decreased strength. Thermal conductivity showed no significant variations due to nanoparticles, with all formulations classified as T2 thermal mortars. The best-performing formulation balanced density, thermal, and mechanical properties effectively, proving suitable for insulating core. Hygric properties within acceptable ranges, with water vapor permeability resistance <15 and capillary water absorption <0.4 kg/m2.min0.5. The findings highlight the potential of Si nanoparticles to improve mechanical performance of porous alkaline cements, offering valuable insights for application in thermal insulation.

Synthesis and Characterization of PVC/(Co3O4/CNT)@Au Semiconductor Nanocomposite for Enhanced Medium-Voltage Cable Insulation

Abstract This study presents the synthesis, characterization, and application of a novel PVC/(Co3O4/CNT)@Au nanocomposite for enhanced medium-voltage cable insulation. The nanocomposite was developed by incorporating Co3O4 octahedron nanoparticles, carbon nanotubes (CNTs), and gold nanoparticles (Au) into a polyvinyl chloride matrix. Compared to standard PVC insulation, the nanocomposite exhibited a 3% improvement in relative permittivity (increased from 2.34 to 2.41) and significantly enhanced field uniformity, as evidenced by simulation studies. Fourier-transform infrared spectroscopy, X-ray diffraction, and electron microscopy confirmed the successful integration of nanofillers and highlighted their contributions to the composite’s properties. Optical characterization revealed a direct bandgap of 4.60 eV and an Urbach energy of 0.3674 eV, indicating a wide-bandgap semiconductor with moderate structural disorder. AC conductivity measurements demonstrated frequency-dependent behavior, while dielectric constant and loss analyses suggested the material’s potential for energy storage and insulation applications. The choice of Co3O4 and CNTs was guided by their synergistic impact on charge trapping, field grading, and thermal management, while Au nanoparticles enhanced charge transfer and local electric field distribution. These findings demonstrate the nanocomposite’s promise in addressing the limitations of traditional PVC insulation, offering improved dielectric performance, reliability, and durability for power transmission and distribution systems.&amp;#xD;

Optimizing double glazing through time and work measurements and simulation

ABSTRACT This study aimed to address the problem of low production rates in the double glazing process of Al Ittihad Company, which initially stood at 170 m 2 /shift (8 hours). The study employed a comprehensive methodology to identify the root causes of the issue and propose effective solutions. The methodology included interviews, data collection, time and motion study (Macro and Micro), root cause analysis, and two simulation modeling scenarios (As-Is) and (To-Be) using Arena software. Through these steps, the study revealed key issues in manual operations for small and large glass products and proposed solutions such as automation of manual pressing and insulator application activities, in addition to enhancing work standardization and employee training. The proposed solutions improvements resulted in a remarkable increase in productivity, reaching 212 m 2 /shift, reflecting a 24.7% improvement. The study also considered economic, ethical, social, and contemporary implications, emphasizing responsible and inclusive approaches. The findings and recommendations highlight the potential for continuous improvement, human-machine collaboration, and supply chain integration to further enhance the double-glazing process and drive sustainable growth in the glass manufacturing industry in Jordan.

Exploitation of Perennial Plant Biomass for Particleboards Designed for Insulation Applications.

With rising demand for wood products and reduced wood harvesting due to the European Green Deal, alternative lignocellulosic materials for insulation are necessary. In this work, we manufactured reference particleboard from industrial particles and fifteen different board variants from alternative lignocellulosic plants material, i.e., five types of perennial plant biomass in three substitutions: 30, 50 and 75% of their share in the board with a nominal density of 250 kg/m3. Within the analysis of manufactured boards, the mechanical, chemical and thermal properties were investigated-internal bond, formaldehyde emissions, thermal insulation, heat transfer coefficient and thermal conductivity. In the case of thermal conductivity, the most promising results from a practical point of view (W/mK < 0.07) were obtained with Sida hermaphrodita and Miscanthus, achieving the best results at 50% substitution. The lowest formaldehyde emissions were recorded for boards with Panicum virgatum and Miscanthus, highlighting their positive environmental performance. In terms of mechanical properties, the highest internal bond was noticed in particleboards with a 30% substitution of Spartina pectinata and Miscanthus. Research findings confirm the potential of perennial plants as a sustainable source of raw materials for insulation panel manufacturing. Despite needing improvements in mechanical properties, most notably internal bond strength, these plants offer an ecologically responsible solution aligned with global construction trends, thus lessening reliance on traditional wood products. Thus, long-term benefits may be realized through the strategic combination of diverse raw materials within a single particleboard.

Poly(p-Phenylene Benzobisoxazole) Nanofiber: A Promising Nanoscale Building Block Toward Extremely Harsh Conditions.

Since the invention and commercialization of poly(p-phenylene benzobisoxazole) (PBO) fibers, numerous breakthroughs in applications have been realized both in the military and aerospace industries, attributed to its superb properties. Particularly, PBO nanofibers (PNFs) not only retain the high performance of PBO fiber but also exhibit impressive nanofeatures and desirable processability, which have been extensively applied in extreme scenarios. However, no review has yet comprehensively summarized the preparation, applications, and prospective challenges of PNFs to the best of our knowledge. Herein, the two fabrication pathways to acquire PNFs from bottom-up to top-down approaches are critically overviewed; the significant advantages and the problem caused simultaneously of the protonation approach compared with other methods are revealed. Besides, the construction strategies of multidimensional PNF-based advanced composites, including 1D fiber, 2D film/nanopaper, and 3D gel, are discussed. Moreover, the outstanding mechanical, insulating, and thermal stability properties of PNFs facilitate their extensive applications in thermal protection, electrical insulation, batteries, and flexible wearable devices, which are further comprehensively introduced. Finally, the perspective and challenges of the fabrication and application of PNFs are highlighted. It demonstrates that the PNFs as one of the promising high-performance nanoscale building blocks can be fully competent using extremely harsh conditions.

Preceramic polymer-hybridized phenolic aerogels and the derived ZrC/SiC/C ceramic aerogels with ultrafine nanocrystallines.

Phenolic and carbon aerogels have important applications for thermal insulation and ablative resistance materials in aerospace field. However, their antioxidant ability in long-term high-temperature aerobic environments faces serious challenges. To solve this problem, Zr/Si preceramic polymer hybridized phenolic resin (PR-ZS) aerogels were prepared via a facile sol-gel method. Compared with pure phenolic aerogel, the hybrid aerogels possess similar porous microstructure but larger specific surface area, better thermo-oxidative stability, and higher compressive strength. After carbonization at 1700 °C, the hybrid aerogels can be transformed to carbide ceramic aerogels with ultrafine nanocrystalline ZrC and SiC particles embedded in the carbon matrix. Ceramic aerogels exhibit good thermal insulative and anti-ablative properties in a butane torch simulated high-temperature and aerobic environment. The linear ablation rate is as low as 0.017 mm min-1, and the backside temperature is below 330 °C at a 20 mm in-depth position after 300 s of burning test, when the front temperature is approximately 960 °C. This work provides a facile approach to fabricate hybrid phenolic aerogels and derived ZrC/SiC/C ceramic aerogels, which target on applications for extreme environments in aerospace field.