Synthesis and Diagnostics of Nanostructured Micaless Microcomposite as a Prospective Insulation Material for Rotating Machines

Hornak, Jaroslav; Mentlík, Václav; Trnka, Pavel; Šutta, P.

doi:10.3390/app9142926

Cited by 6 publications

(4 citation statements)

References 55 publications

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“…The presence of mica in epoxy composites delays thermoelectric aging of epoxy insulation and improves the thermal properties of the epoxy [ 28 ]. Moreover, some reports suggest that mica incorporation into epoxy adhesive enhances the compressive and bending strength [ 29 , 30 , 31 , 32 , 33 ]. Nevertheless, the presence of mica makes the crosslinking kinetics of the epoxy indeed complex and thereof affects the gelation behavior of epoxy resins in insulation usage.…”

Section: Introductionmentioning

confidence: 99%

Epoxy/Ionic Liquid-Modified Mica Nanocomposites: Network Formation–Network Degradation Correlation

et al. 2021

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We synthesized pristine mica (Mica) and N-octadecyl-N’-octadecyl imidazolium iodide (IM) modified mica (Mica-IM), characterized it, and applied it at 0.1–5.0 wt.% loading to prepare epoxy nanocomposites. Dynamic differential scanning calorimetry (DSC) was carried out for the analysis of the cure potential and kinetics of epoxy/Mica and epoxy/Mica-IM curing reaction with amine curing agents at low loading of 0.1 wt.% to avoid particle aggregation. The dimensionless Cure Index (CI) was used for qualitative analysis of epoxy crosslinking in the presence of Mica and Mica-IM, while qualitative cure behavior and kinetics were studied by using isoconversional methods. The results indicated that both Mica and Mica-IM improved the curability of epoxy system from a Poor to Good state when varying the heating rate in the interval of 5–15 °C min−1. The isoconversional methods suggested a lower activation energy for epoxy nanocomposites with respect to the blank epoxy; thus, Mica and Mica-IM improved crosslinking of epoxy. The higher order of autocatalytic reaction for epoxy/Mica-IM was indicative of the role of liquid crystals in the epoxide ring opening. The glass transition temperature for nanocomposites containing Mica and Mica-IM was also lower than the neat epoxy. This means that nanoparticles participated the reaction because of being reactive, which decelerated segmental motion of the epoxy chains. The kinetics of the thermal decomposition were evaluated for the neat and mica incorporated epoxy nanocomposites epoxy with varying Mica and Mica-IM amounts in the system (0.5, 2.0 and 5.0 wt.%) and heating rates. The epoxy/Mica-IM at 2.0 wt.% of nanoparticle showed the highest thermal stability, featured by the maximum value of activation energy devoted to the assigned system. The kinetics of the network formation and network degradation were correlated to demonstrate how molecular-level transformations can be viewed semi-experimentally.

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Section: Introductionmentioning

confidence: 99%

Epoxy/Ionic Liquid-Modified Mica Nanocomposites: Network Formation–Network Degradation Correlation

et al. 2021

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“…In the case of magnesium oxide incorporation into epoxy resin, several research studies have been conducted by Hornak et al [ 46 , 138 , 139 , 140 , 141 ]. From these studies, it is evident that MgO shows good miscibility with the most common type of epoxy-based on bisphenol A epichlorohydrin in its different variations (single and double component, heat and cold cure) and at lower concentrations (close to 1 wt.%), which results in a reduction in internal conductivity within an order of magnitude and can especially be attributed to the reduction of the trapped charge inside the material due to the changes in electron trap density and depth.…”

Section: Selected Technical Applications Of Magnesium Oxidementioning

confidence: 99%

“…In the subsequent final study [ 139 ], the polyethylene napthalate film covered by epoxy resin with dispersed MgO was investigated, and the resulting material was compared with commonly used dielectric materials for insulating of rotating machines. The results show that the designed material achieves qualitatively improved dielectric properties especially with respect to the dielectric strength, volume resistivity, and dielectric losses.…”

Section: Selected Technical Applications Of Magnesium Oxidementioning

confidence: 99%

Synthesis, Properties, and Selected Technical Applications of Magnesium Oxide Nanoparticles: A Review

Hornak

2021

IJMS

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In the last few decades, there has been a trend involving the use of nanoscale fillers in a variety of applications. Significant improvements have been achieved in the areas of their preparation and further applications (e.g., in industry, agriculture, and medicine). One of these promising materials is magnesium oxide (MgO), the unique properties of which make it a suitable candidate for use in a wide range of applications. Generally, MgO is a white, hygroscopic solid mineral, and its lattice consists of Mg2+ ions and O2− ions. Nanostructured MgO can be prepared through different chemical (bottom-up approach) or physical (top-down approach) routes. The required resultant properties (e.g., bandgap, crystallite size, and shape) can be achieved depending on the reaction conditions, basic starting materials, or their concentrations. In addition to its unique material properties, MgO is also potentially of interest due to its nontoxicity and environmental friendliness, which allow it to be widely used in medicine and biotechnological applications.

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“…Epoxy resin is widely utilized and has been considered to be a critical component in achieving safe operation of electrical machines [1][2][3][4][5]. Researchers from all around the world are working to improve the epoxy insulation performance by developing novel insulating materials by incorporating nanofillers into the base epoxy material [6][7][8]. Nanocomposites are considered to have a potential to revolutionize the insulation structure design of rotating machines as well as high voltage apparatus.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Electrical and Thermal Performance of Glass Fiber Reinforced Epoxy–MgO Nanocomposites

Naveen¹,

Babu²,

Sarathi³

et al. 2021

Energies

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Epoxy nanocomposites reinforced with glass fiber, have been prepared with various weight percentages (1, 3, and 5 wt.%) of MgO nanofillers to improve their electrical and thermal performance. An increase in MgO nanofiller content up to 3 wt.% tends to enhance surface discharge and corona inception voltages measured using fluorescence and UHF methods, under both AC and DC voltage profiles. Reduced initial surface potential along with increased decay rate is observed after inclusion of MgO nanoparticles. Before and after the polarity reversal phenomena, heterocharge formation is observed in the bulk of test specimens. In comparison with other test samples, the 3 wt.% sample had reflected lower electric field enhancement factor. After MgO filler was added to glass fiber reinforced polymer (GFRP) composites, the coefficient of thermal expansion (CTE) has reduced, with the 3 wt.% specimen having the lowest CTE value. TGA measurements revealed an improvement in thermal stability of the GFRP nanocomposites up on the inclusion of MgO nanofillers. Overall, the GFRP nanocomposite sample filled with 3 wt.% nano-MgO outperformed the other test samples in terms of electrical and thermal performance.

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Synthesis and Diagnostics of Nanostructured Micaless Microcomposite as a Prospective Insulation Material for Rotating Machines

Cited by 6 publications

References 55 publications

Epoxy/Ionic Liquid-Modified Mica Nanocomposites: Network Formation–Network Degradation Correlation

Epoxy/Ionic Liquid-Modified Mica Nanocomposites: Network Formation–Network Degradation Correlation

Synthesis, Properties, and Selected Technical Applications of Magnesium Oxide Nanoparticles: A Review

Investigation on Electrical and Thermal Performance of Glass Fiber Reinforced Epoxy–MgO Nanocomposites

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