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Over the years, polymeric insulators have emerged with excellent dielectric and other physical properties with the help of increased familiarity with chemistry and physics and improved manufacturing technology. The applications of epoxy nanodielectrics in high-voltage insulation and electronics have increased greatly in recent decades. In the energy industry, various polymer materials, including thermoplastics, thermosets, glass, and natural fibers, have been employed because of their superior performance and long lifespan in extreme environments. Epoxy resins containing appropriate nano and micro-organic particles have gained popularity for practical applications in various electrical power apparatuses and systems. By incorporating nanofiller into epoxy resin matrices, these materials exhibit significant improvements in dielectric strength, thermal conductivity, partial discharge resistance, and long-term reliability compared to conventional epoxy systems. This chapter presents an inclusive overview of epoxy nanodielectrics, addressing material design, nanofiller selection, interfacial engineering, and synthesis methods essential for achieving uniform dispersion and optimized-blended properties. Key electrical, thermal, and mechanical characteristics are discussed for high-voltage apparatuses such as transformer bushings, current and voltage transformers, switchgear, and cast resin transformers. Additionally, the chapter addresses challenges related to the synthesis processes and scalability of epoxy nanocomposites, along with future trends toward multifunctional and environmentally sustainable insulating materials. The applicable test standards and material characterization methods are highlighted to provide comprehensive understanding of performance evaluation of epoxy nanodielectrics in HV systems.
*Address all correspondence to: mihir.velani@adaniuni.ac.in
1. Introduction
Solid insulating materials are indispensable part of electrical power systems. For a long time, porcelain (ceramic) has been popular for its superior dielectric properties and robustness. As the power transmission voltages increase, the requirement of lightweight new insulations with multifunctional properties has led to significant growth in polymeric materials. Epoxy has emerged as an innovative product, offering excellent dielectric, thermal, and mechanical properties due to its unique processability and compatibility with a range of inorganic micro- and nanofillers [1, 2, 3]. Over the past two decades, the addition of nanofillers into epoxy has transformed epoxy resins into advanced nanodielectrics that claim excellent dielectric strength, improved thermal conductivity, and high partial discharge (PD) resistance and weatherproof.
This chapter presents a typical review of epoxy-based nanodielectrics, probing key aspects including selection and synthesis of the material, interfacial engineering, conception of material properties, characterization methods, applications, and the recent developments in the stirring field.
Over more than four decades, porcelain insulators were dominating solid insulation systems in transmission lines and power apparatuses owing to its chemical inertness and withstand ability to perform in harsh environmental conditions. Conversely, their heavy weight, brittleness, and manufacturing complexity made them restricted to large and complex power equipment. Gradually, the industry moved to glass insulators offering transparency in fault detection and lower production erraticism. Yet, glass suffered from mechanical fragility and was not well-suited for high-voltage station equipment. In parallel, mica and cotton-based materials were adopted for capacitors and cables, often impregnated with oil to improve dielectric strength. These were effective in the short term but prone to moisture ingress and thermal degradation, leading to premature failure [4, 5].
By the mid-twentieth century, oil-impregnated paper (OIP) systems became standard for transformer bushings and cables. While OIP systems provided high dielectric strength, their susceptibility to moisture and the need for maintenance triggered off research into more robust alternatives.
2.2 Polymeric revolution
The statistics reveal a sharp rise in electricity demand, which particularly impacts the power system in terms of operating voltage levels, overall size, and system intricacy. While higher voltage levels have enhanced the robustness and cost-effectiveness of power networks, solid insulators continue to confront challenges related to weight, cost, size constraints, and the combined influence of electric fields and thermal stresses. Despite these limitations, solid insulators remain integral components of electrical equipment, providing both insulation and mechanical support. However, they are constantly subjected to over voltages as well as extreme environmental and pollution conditions, which can compromise their performance [6, 7, 8, 9]. To address these challenges, it is crucial to devise next-generation insulators that offer enhanced electrical and thermal properties. Material innovation has evolved as existing technologies met barriers and material science progressed.
The progress of electrical insulation materials has always paralleled advances in electrical equipment. In the past, devices such as transformers, cables, and capacitors relied on mica, cotton threads or fabrics, and oil-impregnated paper for insulation. Over time, non-ceramic or polymeric insulators emerged, with the first such materials being used in 1963 [10]. Each phase of material innovation was compelled by constraints in the existing technology, in tandem with advancements in materials science and manufacturing. The insulators were particularly introduced to overcome the limitations of ceramic types in specific environments. Due to ongoing research and development, it is now feasible to devise polymeric insulators for specific applications, delivering enhanced reliability and performance. The introduction of synthetic polymers represented a paradigm shift. Thermoplastics such as polyethylene and polyvinyl chloride (PVC) offered lightweight alternatives but were constrained by thermal stability. The breakthrough came with thermosetting polymers, particularly epoxy resins. Epoxies demonstrated excellent moldability, dimensional stability, and dielectric performance. Their cross-linked structure enabled them to withstand high electrical and thermal stress. Industrial adoption accelerated in the 1960s and 1970s, with epoxy systems replacing ceramics with medium- and high-voltage switchgear, instrument transformers, and cast-resin transformers [11, 12]. Figure 1 depicts a timeline with approximate periods during which different solid insulators gained popularity in electrical power systems.
Figure 1.
Timeline of solid insulator development.
The ability to engineer epoxy formulations to specific requirements—by varying curing agents, modifiers, and fillers—offered unprecedented flexibility. This “polymeric revolution” not only condensed reliance on ceramics but also allowed compact equipment designs, reduced installation weight, and enhanced manufacturing scalability.
2.3 Nanotechnology revolution
Nanodielectrics revolutionized the power sector in the twenty-first century. Unlike traditional micro-fillers, nanofillers influence the material at the interfacial level, creating new pathways for charge trapping, dielectric relaxation, and thermal conduction [13]. Epoxy nanodielectrics demonstrated noticeable improvements in dielectric breakdown strength, partial discharge resistance, and thermal conductivity compared to conventional systems [14]. Carbon nanotubes, graphene, silica nanoparticles, and boron nitride nanosheets became subjects of extensive research. Today, epoxy nanodielectrics are being evaluated for a wide range of power equipment, from transformer bushings and gas-insulated switchgear to cast-resin transformers. Their multifunctionality, combining electrical and thermal enhancements, positions them as a base material for the next generation of high-voltage technology.
Thermosetting epoxy resins are formed by the reaction of epoxide groups with curing agents, for instance, anhydrides or amines. The resulting cross-linked network imparts mechanical rigidity, thermal resistance, and dielectric stability. Two common industrial grades are bisphenol-A diglycidyl ether (DGEBA) and bisphenol-F epoxies [15]; the chemical structures are illustrated in Figure 2. The key properties of epoxy matrices include the following:
High dielectric strength and high electrical resistivity
Low loss factor
High treeing-tracking resistance
Excellent chemical resistance and moisture resistance
Tunable mechanical and thermal properties through curing chemistry
Strong adhesion to fibrous and metallic reinforcements.
Figure 2.
Chemical structure of (a) bisphenol-A diglycidyl ether (DGEBA) (b) bisphenol-F.
3.2 Nanofillers and nanodielectrics
A class of hybrid organic-inorganic materials is known as nanodielectrics and also termed as nanocomposites. They contain a trace amount of inorganic nanofillers homogeneously dispersed in polymers with at least one dimension in the 1–100 nm range [2]. Figure 3 provides a schematic representation; the polymer-based nanodielectrics are intended for illustrative purposes only. Nanofillers are introduced to overcome the limitations of neat epoxy resins. Due to their small size (1–100 nm) and high surface area, polymer-based nanocomposites form large and strong interfacial regions with the polymer matrix. As a result, they are increasingly used in electrical machines, solid-insulated switchgear, HV cables, dense electronic assemblies, energy generation, or storage systems [3, 13, 16, 17]. These materials are becoming popular in smart applications for energy, healthcare, and photonic and organic electronic devices [18].
Figure 3.
Schematic representation of nanodielectric formation via nanoparticle dispersion.
Epoxy nanodielectrics have grabbed attention for HV indoor and outdoor applications due to their affordable and structural versatility. This adaptability stems from the integration of particulate nano-and micro-scale fillers such as alumina, alumina (Al2O3), boron nitride (BN), magnesium oxide (MgO), nano clay, silica (SiO2), titania (TiO2), zinc oxide (ZnO), graphene [19], graphene dioxide [20], and many others. Moreover, carbon nanotubes (CNTs), graphene and nitride nanosheets, have become the subject of extensive research. Commonly used nanofillers in epoxy insulation are summarized in Table 1.
Integrating nanofillers into epoxy resin considerably improves key functional properties, including dielectric permittivity, dielectric breakdown strength, treeing resistance, tracking and erosion resistance, glass transition temperature (Tg), thermal conductivity, and elastic modulus [13]. Furthermore, there is still debate on the interfacial dynamics, which are affected by a variety of factors. Notwithstanding substantial progressions in the field, two persistent technological challenges continue to impede progress: (1) Ensuring homogeneous dispersion of fillers within the host matrix, and (2) Optimizing both the selection and surface functionalization of nanofillers to enhance compatibility and performance [21]. The uniform dispersion is dependent on the intrinsic properties of the base material, type, size, shape and properties of nanofillers, the dispersion method, and the used solvent. Both the synthesis process and the surface condition of the nano fillers give positive results. This makes it necessary to consider a range of factors to investigate the performance of the nanodielectrics. The materials are evaluated and characterized with the help of sophisticated instruments and methods.
The synthesis process significantly affects the performance of epoxy nanodielectrics. Additionally, nanoparticles’ size and shape, surface treatment and chemistry, dispersion in the epoxy matrix, and processing environment need precise control [22, 23, 24]. These ensure good interfacial regions between epoxy resin and nanoparticles.
4.1 Material selection
To begin, the synthesis process requires the selection of a base resin, solvent and curing agent, and nanofiller system.
Epoxy resins: DGEBA is the most often utilized epoxy type due to its dielectric stability, good mechanical strength, and ease of processing. Cycloaliphatic epoxies are recommended when higher thermal resistance, chemical stability, toughness, and low viscosity are required [25]. In contrast, Novolac, is the precursor of Bakelite, which is a hard cross-linked thermosetting polymer [26].
Curing agents: Amine, anhydride, and acid-based hardeners regulate crosslink density and thermal behavior. Optimized curing periods are important for effective mixing with nanofillers [27].
Nanofillers: Common fillers include Al2O3, BaTiO2 (barium titanate), BeO (Beryllium Oxide), BN, Nano Clay, SiO2, TiO2, and ZnO [19, 20, 28]. Recently, carbon-based allotropes such as CNTs and graphene are progressively employed for multifunctional properties [29].
4.2 Surface functionalization and interfacial engineering
Direct incorporation of nanoparticles into epoxy often results in agglomeration due to high surface energy and poor compatibility with the polymer matrix. Therefore, a special treatment called surface functionalization is required for improved interaction between base material and nanofillers. Surface functionalization is the process of adding specific chemical molecules to a material’s surface to change its properties, while interfacial engineering is a broader approach that optimizes the boundary between varied materials.
Sol-gel method: In the sol-gel process for epoxy-nanodielectrics, inorganic nanofillers undergo hydrolysis and condensation, followed by surface modification for compatibility. These are uniformly dispersed into the epoxy matrix and cured, yielding composites with enhanced dielectric and thermal properties [30, 31].
Silane coupling agents: Organosilanes are commonly applied to increase chemical bonding between inorganic fillers and the organic epoxy resin. Silane-treated ZnO nanoparticles, for example, demonstrate improved wettability and stable filler dispersion [32].
Polymer grafting: In certain cases, nanoparticles are grafted with polymer chains to achieve enhanced miscibility and minimize phase separation [33].
Plasma and chemical treatments: Surface activation through plasma oxidation or acid treatment is used for CNTs and graphene, introducing oxygen-containing groups that facilitate bonding with the epoxy matrix [34].
By stabilizing dispersion and controlling interfacial polarization, progressive interface design significantly improves dielectric and thermal properties.
4.3 Dispersion techniques
Achieving uniform dispersion of nanofillers within the base resin is the most crucial step in the synthesis of nanodielectrics. Several techniques are used, often in combination, to avoid agglomeration of nanoparticles [35].
Mechanical stirring: This is the initial phase where nanoparticles are incorporated into the epoxy resin using high shear mixers. However, it sometimes results in poor uniformity with high filler concentrations.
Ball milling: Ball milling offers a uniform dispersion of nanofillers for certain strong filler system, but it can lead to epoxy resin contamination if not accurately monitored.
Ultrasonication: This method employs high-frequency ultrasonic waves to ensure uniform dispersion of nanofillers in epoxy resin. The ultrasonic probe sonication (usually at 20 kHz, 750 W) proves to be more effective than bath sonication (typically at 40 kHz, 180 W). It is important to control the sonication duration as prolonged sonication produces excessive heat that could degrade the resin’s molecular structure.
Solution casting: The epoxy is first steered with a solvent (ethanol/methanol/acetone). Then, the nanoparticles are uniformly dispersed in the mixture of epoxy and solvent. This mixture is heated on a hot plate to evaporate the solvent. However, this process occasionally leaves behind the residues that may compromise the dielectric purity if not closely monitored.
In-situ polymerization: It is a new method that involves dispersing nanoparticles in monomers prior to polymerization. This ensures enhanced interactions between the base matrix and fillers, resulting in better interfacial bonding [36].
4.4 Mixing and degassing
To avoid particle agglomeration, the epoxy and nanofillers must be homogenously mixed with solvent and curing agents. Afterwards, vacuum degassing is typically performed to extract the trapped gases and air bubbles which could form voids and result in premature dielectric/thermal failure.
4.5 Curing process
The cross-linking density, mechanical integrity, and thermal stability of epoxy nanocomposites are determined by the curing process. Two major stages should be considered:
Conventional thermal curing: This process involves controlled heating cycles (e.g., room-temperature pre-curing followed by post-curing at 100–120°C) to allow for gradual cross-linking between epoxy resin and nanofillers and stress relaxation. Here, the curing temperature must be less than the glass transition temperature of the epoxy.
Ultraviolet (UV) and electron-beam curing: New approaches that support rapid polymerization and precise control are becoming more common. These strategies are especially preferred for thin-film coatings, but they have been remained less explored for bulk insulation applications [37].
It is essential to regulate curing contraction carefully, as improper treatment may result in microcracks and voids developing around interfacial regions between nanoparticles and epoxy resins.
4.6 Scalability challenges
Although laboratory-scale synthesis has demonstrated continuous improvements in material performance, transitioning to industrial-scale production presents significant challenges.
Nanoparticle agglomeration at high volumes: Industrial mixers usually struggle to achieve uniform dispersion of nanoparticles when working at kilogram to ton scales.
Material synthesis duration and cost: The extraction of high-purity nanoparticles from complex chemical processes and the use of advanced dispersion methods can extremely increase the overall cost of manufacturing nanodielectrics.
Standardization issues: There is no universally accepted processing norms for nano filled epoxy systems. This lack of standardization leads to variability in commercial products.
Health and environmental safety: The handling of nanofillers, curing agents, and epoxy resins requires stringent safety protocols to minimize the risks of inhalation and contamination.
The synthesis and processing of epoxy nanodielectrics require precise control over every stage, from material selection to dispersion and curing. While considerable progress has been made in laboratory-scale procedures, bridging the gap toward scalable, reproducible, and environmentally sustainable processing remains a continuing challenge. The research in interfacial dynamics and industrial-scale dispersion will be central to the future commercialization of these materials.
Epoxy-based nanocomposites have attracted overall attention in high-voltage insulation due to their unique ability to blend the promising aspects of polymer matrices with the functional merits of nanofillers. The interaction between polymer chains and nanofillers governs the electrical, thermal, and mechanical properties of these composites [13]. This section delivers a detailed study of the major properties relevant to the performance of epoxy nanodielectrics.
5.1 Electrical properties
The electrical performance of epoxy nanodielectrics is vital for high-voltage systems. The main properties—dielectric constant, dielectric loss, dielectric strength, and resistance to partial discharges—are significantly affected by the type and dispersion of nanofillers.
5.1.1 Dielectric constant and dielectric loss factor
The incorporation of nanofillers changes the dielectric permittivity of the epoxy matrix by introducing additional polarization mechanisms at the filler-matrix interfaces. The polarization mechanism is introduced at varied frequencies and different temperatures. The inorganic nanofillers often enhance interfacial polarization due to their high surface area, allowing greater charge storage and localized field distribution [38]. At low filler concentrations (<5 wt%), a subtle increase in dielectric constant is typically observed without significantly increasing dielectric loss. However, excessive filler loadings may introduce percolation that elevates dielectric losses [39]. Frequency-dependent dielectric spectroscopy under varying relative humidity (%RH) and temperature conditions helps a thorough analysis of real ε′ and imaginary ε″ permittivity (Figure 4), explaining dielectric polarization, relaxation process, and conduction loss mechanisms in dielectric materials [40].
Figure 4.
Frequency dependent (a) ε′ (b) ε″ of neat epoxy (EP) and nanocomposites (AAR-alumina as-received, TAR-titania as-received, ZAR-zinc oxide as-received) with 1% volume fraction at 25% RH and 90°C [40].
5.1.2 Dielectric breakdown strength
Epoxy nanodielectrics have shown increased dielectric breakdown strength because of reduced space charge buildup and electron scattering within their complex microstructure. The surface treated TiO2-SiO2 core-shell structure in epoxy has achieved more superior breakdown resistance compared to neat epoxy (refer to Figure 5) [22]. It is also true that further increase in the filler loading attracts particle agglomeration leading to the reduced breakdown strength.
Figure 5.
DC breakdown strength for epoxy filled with raw TiO2 and TiO2-SiO2 core-shell nanoparticle [22].
5.1.3 Partial discharge and surface tracking resistance
Partial discharge resistance is important for longevity of solid insulation. It has been observed that the nanofillers increase PD resistance by filling micro-void growth and alleviating the epoxy resin-filler interface under high voltage electric stress. Epoxy nanodielectrics exhibit superior resistance to surface treeing-tracking and erosion as compared to neat epoxy under high-humidity or contaminated conditions [41, 42, 43, 44].
5.2 Thermal properties
Since the localized overheating often speeds up the degradation of insulation, thermal functioning is also a critical parameter in determining the fitness of the epoxy nanodielectrics for use in electrical power applications.
5.2.1 Thermal conductivity
Neat epoxy resins show relatively low thermal conductivity (~0.2 W/mK). The addition of high-thermal-conductivity nanofillers such as BN, ZnO, or graphene derivatives can substantially enhance thermal conductivity. Literature works indicate that epoxy/BN and epoxy/ZnO nanocomposites offer 2-3 times higher thermal conductivity with only moderate filler content [1]. This enhancement reduces hotspot formation and improves thermal management in high-power apparatuses.
5.2.2 Glass transition temperature (Tg)
The introduction of nanofillers impacts the glass transition temperature by either restricting polymer chain mobility, relying on filler–matrix interactions. Strong interfacial bonding, usually achieved through surface functionalization and silane coupling agents, generally increases Tg by restricting chain relaxation dynamics. A higher Tg ensures thermal stability under elevated temperatures (refer to Figure 6) [45].
Figure 6.
Glass transition temperature of alumina filled epoxy nanodielectrics [45].
Thus, epoxy nanodielectrics blend higher dielectric strength with improved thermal conductivity, enabling reliable performance in high-voltage insulation systems.
5.3 Mechanical properties
Mechanical robustness is indispensable for insulation systems subjected to dynamic stresses such as vibration, cantilever loading, and installation-induced stresses.
5.3.1 Tensile and flexural strength
The incorporation of nanofillers, particularly SiO2 and clay, enhances load transfer efficiency, resulting in improved tensile and flexural strength [46].
5.3.2 Fracture toughness
Nanoparticles reinforce the toughness through mechanisms such as crack path deflection, interfacial energy dissipation, and particle pull-out, collectively delaying crack propagation [47].
5.3.3 Fatigue and creep resistance
Epoxy nanocomposites exhibit excellent resistance to fatigue and creep, thereby assuring long-term mechanical stability in high-voltage insulation applications.
Epoxy nanodielectrics have found growing applications in modern high-voltage technology, where superior dielectric strength, thermal stability, and mechanical robustness are required. A few plausible applications are summarized here [48].
Transformer bushings: Epoxy nanodielectrics as oil-end insulator can offer compact, moisture-resistant alternatives to OIP bushings. They withstand impulse stresses and exhibit superior reliability under environmental exposure.
Instrument transformers: Nanodielectrics resist partial discharge activity, improving their metering accuracy and long-term stability.
Switchgear and gas-insulated substation (GIS): In compact HV switchgear, epoxy nanocomposites provide high dielectric strength and arc resistance. They also support the move toward SF6-free insulation systems.
Cast-resin transformers: Nanodielectrics enhance winding insulation, offering better flame retardancy and thermal conductivity compared to neat epoxy.
The qualification of epoxy nanodielectrics depends on standardized evaluations such as IEC/IEEE norms for dielectric strength, permittivity, and tracking resistance, alongside ASTM/ISO methods for thermal and mechanical performance. On the other side, advanced techniques, including dielectric spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM), facilitate accurate insights into surface morphology, filler dispersion, interfacial polarization, and structural integrity.
7.1 Electrical testing standards
Electrical properties form the foundation of insulation performance. The most widely adopted standards are mentioned in Table 2.
Standards
Purpose
IEC 60243
For measuring dielectric breakdown strength of solid insulation materials.
IEC 60250
For relative permittivity and dielectric dissipation factor.
IEC 60587
For evaluating tracking and erosion resistance under surface stress conditions.
IEC 60112
For the estimation of the comparative tracking indications of solid insulating materials.
Table 2.
IEC standards for electrical testing of solid polymeric insulators.
The partial discharge testing (IEC 60270) and frequency-domain dielectric spectroscopy are the two complementary methods that allow precise monitoring of charge accumulation, interfacial polarization, and relaxation dynamics under varying frequencies and voltages.
7.2 Thermal characterization
The ability of epoxy nanodielectrics to withstand thermal stress is evaluated through established practices:
Differential scanning calorimetry (DSC) (as per ASTM E1356) – to determine glass transition temperature (Tg).
Thermogravimetric analysis (TGA) (as per ASTM E1131) – to evaluate thermal stability and decomposition temperature.
Laser flash analysis (as per ASTM E1461) – for thermal conductivity measurement.
7.3 Mechanical testing
Mechanical integrity is critical for components subjected to cantilever forces, vibrations, and installation stresses. The typical standards include the following:
ASTM D638 – for the measurement of tensile strength and elongation.
ASTM D790 – for the determination of flexural strength.
ASTM D5045 – for the estimation of fracture toughness.
ISO 899 – for the assessment of creep and stress relaxation behavior.
These assessments validate the mechanical durability of epoxy nanocomposites, exclusively in applications involving external exposure or mechanical loading.
7.4 Sophisticated diagnostic tools
While standard bulk assessments remain foundational, in context to surface and molecule interaction and dielectric properties, advanced characterization methodologies, facilitate a nuanced (micro- t -nanoscale) understanding of epoxy nanodielectrics at finer spatial resolutions:
Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) – to verify nanofiller dispersion and detect agglomeration.
Atomic force microscopy (AFM) – for investigating nanoscale surface topography and mechanical modulus mapping.
X-ray diffraction (XRD) – for confirming crystalline structures or intercalation in layered fillers such as clays.
Fourier transform infrared spectroscopy (FTIR) – for detecting chemical bonding and surface functionalization effects.
Dielectric spectroscopy – to explore interfacial polarization and relaxation processes across a wide frequency range (e.g., 10 μHz to 10 kHz) and at different temperatures.
Despite their promise, epoxy nanodielectrics encounter limitations in large-scale industrial applications. The key challenges include the following:
Achieving uniform nanofiller dispersion at low cost.
Establishing standardized testing protocols tailored to nanocomposites.
Balancing multifunctionality with manufacturability.
Ensuring environmental sustainability by adopting bio-based epoxies and recyclable fillers.
The ongoing research focuses on multifunctional nanodielectrics (carbon allotropes- carbon nanotubes and graphene) that combine electrical, thermal, and mechanical improvements, while also incorporating environmental considerations. In addition, hybrid filler systems comprising 2D and 3D nanostructures may yield synergistic effects. The inclusion of artificial intelligence and computational modeling is also anticipated to play an increasing role in the design and optimization of such materials.
Epoxy nanodielectrics depict a transformative advancement in electrical insulation, offering superior dielectric, thermal, and mechanical properties. Their potential to enable compact, reliable, and sustainable power systems is deductible from emerging research. Yet, the challenges in scalable processing, environmental compatibility, and standardized evaluation persist. Future measures will likely focus on multifunctional formulations, bio-based matrices, and recyclable fillers, guided increasingly by artificial intelligence and computational modeling. As the energy sector evolves, epoxy nanocomposites are poised to become foundational materials in next-generation high-voltage technology.
The author gratefully acknowledges Adani University for providing the necessary digital infrastructure and resources that supported the successful completion of this work.
Conflict of interest
The authors declare no conflict of interest.
References
1.Tanaka T, Vaughan AS. Tailoring of Nanocomposite Dielectrics: From Fundamentals to Devices and Applications. 1st ed. Singapore: Pan Stanford; 2017. pp. 44-64. DOI: 10.1201/9781315201535
2.Frechette MF. What are nanodielectrics? IEEE Electrical Insulation Magazine. 2013;29:8-11. DOI: 10.1109/MEI.2013.6648747
3.Zhong SL, Dang ZM, Zhou WY, Hui-Wu C. Past and future on nanodielectrics. IET Nanodielectrics. 2019;1:41-47. DOI: 10.1049/iet-nde.2018.0004
4.New A. Some mechanisms of failure of capacitors with mica dielectrics. The Institution of Electrical Engineers. 1962;109:488-495. DOI: 10.1049/pi-b-2.1962.0084
5.Olatoundji G, Amanda VS, Eric D, Ioana P. Review of technologies and materials used in high-voltage film capacitors. Polymers. 2021;13:1-18. DOI: 10.3390/polym13050766
6.Suchitra M, Renukppa NM, Ranganathaiah C, Rajan JS. Correlation of free space length and surface energy of epoxy nanocomposites to surface tracking. IEEE Transactions on Dielectrics and Electrical Insulation. 2019;25:2129-2138. DOI: 10.1109/TDEI.2018.007194
7.Tsekmes IA, Morshuis PHF, Smit JJ, Kochetov R. Enhancing the thermal and electrical performance of epoxy micro composites with the addition of nanofillers. IEEE Transactions on Dielectrics and Electrical Insulation. 2015;31:32-42. DOI: 10.1109/MEI.2015.7089120
8.Kavitha D, Nambiar TK. Impact of permittivity and concentration of filler nanoparticles on dielectric properties of polymer nanocomposites. IET Science, Measurement and Technology. 2017;11:179-185. DOI: 10.1109/TDEI.2018.007194
9.Wu K, Wang Z, Zhao C, Huang Z, Li J, Li S. Surface treeing and segmented worm model of tracking behavior in MgO/epoxy nanocomposites. IEEE Transactions on Dielectrics and Electrical Insulation. 2018;25:2067-2075. DOI: 10.1109/TDEI.2018.007120
10.Maclean-Fogg. A Historical Glimpse of Electrical Insulators [Internet]. 2022. Available from: https://macleanfogg.com/a-historical-glimpse-of-electrical-insulators/ [Accessed: October 2, 2025]
11.Banerjee S, Shelly S, Shakti P. Electrical discharge resistance of polymeric nanocomposites. IET Nanodielectrics. 2021;4:210-222. DOI: 10.1049/nde2.12019
12.Cherney E. Nanodielectrics applications – Today and tomorrow. IEEE Dielectric Insulation Magazine. 2013;29:58-65. DOI: 10.1109/MEI.2013.6648754
13.Takahiro I, Yoshiyuki I, Masayoshi N, Tetsuo Y, Kazutoshi G, Takanori K, et al. Advanced Nanodielectrics: Potential Applications in Electric Power and Electronics Sectors. Singapore: Pan Stanford; 2017. pp. 19-86. DOI: 10.1201/9781315230740
14.Mohanty A, Srivastava VK. Dielectric breakdown performance of alumina/epoxy resin nanocomposites under high voltage application. Materials & Design. 2013;47:711-716. DOI: 10.1016/j.matdes.2012.12.052
15.Czifrák K, Lakatos C, Szabó G, Vadkerti B, Daróczi L, Zsuga M, et al. Bisphenol a Diglycidyl ether-primary amine cooligomer-poly(ε-caprolactone) networks: Synthesis and characterization. Polymers. 2023;15:2937. DOI: 10.3390/polym15132937
16.Illona P, Petru N, Sandra S, Christof S, Micheal M. Properties of polymer composites used in high-voltage applications. Polymers. 2016;8:1-63. DOI: 10.3390/polym8050173
17.Marco N, Liu J, Kristy V. Synthesis and applications of carbon nanomaterials for energy generation and storage. Beilstein Journal of Nanotechnology. 2016;7:149-196. DOI: 10.3762/bjnano.7.17
18.Andreas T, Fabrice L, Pierre R. Advanced hybrid nanomaterials. Beilstein Journal of Nanotechnology. 2019;10:2563-2567. DOI: 10.3762/bjnano.10.247
19.Naveh N, Shepelev O, Kenig S. Enhancement of mechanical and electrical properties of continuous fiber reinforced epoxy composites with stacked graphene. Beilstein Journal of Nanotechnology. 2017;8:1909-1918. DOI: 10.3762/bjnano.8.191
20.Khan MI, Siddiqi HM, Park CH, Kim B, Hassan M, Toheed A. High-performance epoxy nanocomposites with enhanced thermal and mechanical properties by incorporating amine-terminated oligoimidegrafted graphene oxide. High Performance Polymers. 2019;32:569-587. DOI: 10.1177/0954008319888670
21.Mihir V, Ritesh P. Epoxy-based ZnO nanocomposites in various configurations: Corona discharges and thermal transition studies. High Performance Polymers. 2023;35:1-14. DOI: 10.1177/09540083231167743
22.Chen Y, Wu J. Investigation on relationship between breakdown strength enhancement of composites and dielectric characteristics of nanoparticle. IEEE Transactions on Dielectrics and Insulations. 2016;23:927-934. DOI: 10.1109/TDEI.2015.005378
23.Connor D, Weixing S, Michael K, Xiaoli T, Nicola B. Modelling the interphase of a polymer-based Nanodielectric. IEEE Transactions on Dielectrics and Insulations. 2014;21:488-496. DOI: 10.1109/TDEI.2015.005378
24.Michel F, Ioana P, Castellon J, Andrej K, Veillette R, Michel T, et al. Polymer composites with a large Nanofiller content: A case study involving epoxy. IEEE Transactions on Dielectrics and Insulations. 2014;21:434-443. DOI: 10.1109/TDEI.2013.004164
25.Atusuomi S, Satoru Y, Keiji T. Network formation and physical properties of epoxy resins for future practical applications. ACS Publications. 2022;2:1522-1542. DOI: 10.1021/jacsau.2c00120
26.Croitoru C. 1000 at 1000: The lightest Bakelite and beyond. Journal of Materials Science. 2020;55:15637-15642. DOI: 10.1007/s10853-020-05038-y
27.Szymon K, Paula OP, Ewa W, Jakub T. Anhydride-cured epoxy powder coatings from natural-origin resins, hardeners, and fillers. Coatings. 2021;11:1-13. DOI: 10.3390/coatings11050531
28.Takahiro I. Tailoring of Nanocomposite Dielectrics. 1st ed. Singapore: Pan Stanford; 2017. pp. 41-85. DOI: 10.1201/9781315201535
29.Sortirios S, Sanida A, Psarras G. Carbon allotropes/epoxy nanocomposites as capacitive energy storage/harvesting systems. Applied Sciences. 2021;11:1-14. DOI: 10.3390/app11157059
30.Dmitry B, Abduladheem J, Supat C, Wanich S, Mohammad J, Iman S, et al. Nanomaterial by sol-gel method: Synthesis and application. Advances in Materials Science and Engineering. 2021;2021:1-21. DOI: 10.1155/2021/5102014
31.Mansour S, Elsad R, Izzularab M. Dielectric investigation of high-density polyethylene loaded by ZnO nanoparticles synthesized by sol–gel route. Journal of Sol-Gel Science and Technology. 2016;80:333-341. DOI: 10.1007/s10971-016-4109-x
32.Suresh S, Nisha P, Saravanan P, Jayamoorthy K, Karthikeyan S. Investigation of the thermal and dielectric behavior of epoxy Nano-hybrids by using Silane modified Nano-ZnO. Silicon. 2018;10:1291-1303. DOI: 10.1007/s12633-017-9604-3
33.Yajing Y, Jiye Y, Fenglin L, Dayin S, Jintao Z, Zhihong N, et al. Stepwise grafting of polymer single chains onto nanoparticles. Macromolecules. 2025;58:1256-1264. DOI: 10.1021/acs.macromol.4c03032
34.Hieda J, Shirafuji T, Noguchi Y, Saito N, Takai O. Solution plasma surface modification for nanocarbon-composite materials. Journal of Japan Institute of Metals and Materials. 2009;73:938-942. DOI: 10.2320/jinstmet.73.938
35.GETNANO. How to Properly Disperse Nanoparticles or Microparticles and Avoid Agglomeration Issues [Internet]. 2015. Available from: https://www.getnanomaterials.com/kb/how-to-properly-disperse-nanoparticles-or-microparticles-and-avoid-agglomeration-issues/ [Accessed: October 2, 2025]
36.Miraidin M, Mathieu R, Brahim B. In situ processing to achieve high-performance epoxy nanocomposites with low graphene oxide loading. Journal of Carbon Research. 2024;10:1-12. DOI: 10.3390/c10020052
37.Ashwarya S, Sandeep K, Debashish K. A review on recent development and application of radiation curing. Materials Today Proceedings. 2023;82:68-74. DOI: 10.1016/j.matpr.2022.11.342
38.Tanaka T, Montanari G, Mulhaupt R. Polymer nanocomposites as dielectrics and electrical insulation-perspectives for processing technologies, material characterization and future applications. IEEE Transactions on Dielectrics and Insulations. 2004;11:763-784. DOI: 10.1109/TDEI.2004.1349782
39.Siny P, Sindhu T. Development of epoxy-aluminum nanocomposite dielectric material with low filler concentration for embedded capacitor applications. IEEE Transactions on Dielectrics and Insulations. 2013;21:460-466. DOI: 10.1109/TDEI.2013.004175
40.Ritesh P. Dielectric properties of epoxy based composites with various metal oxide nanofillers [thesis]. Kanpur: Indian Institute of Technology; 2013
41.Parimal M, Subramanyam K, Venkitanarayanan P, Sumit B, Nandini G. Improvement in surface degradation properties of polymer composites due to pre-processed Nanometric alumina fillers. IEEE Transactions on Dielectrics and Insulations. 2008;15:83-72. DOI: 10.1109/T-DEI.2008.4446737
42.Preetha P, Thomas M. Partial discharge resistant characteristics of epoxy nanocomposites. IEEE Transactions on Dielectrics and Insulations. 2011;18:264-274. DOI: 10.1109/TDEI.2011.5704518
43.Zhe L, Kenji O, Yoshimichi O, Toshikatsu T. The role of Nano and Micro particles on partial discharge and breakdown strength in epoxy composites. IEEE Transactions on Dielectrics and Insulations. 2011;18:675-681. DOI: 10.1109/TDEI.2011.5931052
44.Iyer G, Gorur R, Krivda A. Corona resistance of epoxy nanocomposites: Experimental results and modelling. IEEE Transactions on Dielectrics and Insulations. 2012;18:18-125. DOI: 10.1109/TDEI.2012.6148509
45.Siny P, Sindhu T. Effect of filler particle size on electric energy density of epoxy-aluminum nanocomposites. IEEE Transactions on Dielectrics and Insulations. 2016;23:2786-2794. DOI: 10.1109/TDEI.2016.7736838
46.Park J, Lee C, Lee J, Kim H. Preparation of epoxy/micro- and nanocomposites by electric field dispersion process and its mechanical and electrical properties. IEEE Transactions on Dielectrics and Insulations. 2011;18:667-674. DOI: 10.1109/TDEI.2011.5931051
47.Lazzeri A, Zebarjad S, Pracella M, Cavalier K, Rosa R. Filler toughening of plastics. Part 1: The effect of surface interactions on physico-mechanical properties and rheological behavior of ultrafine CaCO3/HDPE nanocomposites. Polymer. 2025;46:827-844. DOI: 10.1016/j.polymer.2004.11.111
48.Tanaka T, Imai T. Advances in nanodielectric materials over the past 50 years. IEEE Electrical Insulation Magazine. 2023;29:10-23. DOI: 10.1109/MEI.2013.6410535
Written By
Mihir Velani
Submitted: 06 October 2025Reviewed: 24 October 2025Published: 21 November 2025
Open access peer-reviewed chapter
