Abstract
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.
Highlights
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]
In comparison to the pure epoxy sample reinforced with glass fiber, the addition of MgO nanoparticles to the epoxy resin inhibited the accumulation of space charge, resulting in lesser intensification in electric field in epoxy–MgO nanocomposites after polarity reversal (Figure 13)
Reduced initial surface potential and increased λ is noticed after inclusion of MgO nanoparticles
Summary
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]. Hildinger et al have stated that the incorporation of SiO2 nanofillers in epoxy-mica insulation have resulted in a highly efficient stator winding insulation, which has improved specific power output without reduction on insulation lifetime [9] Due to their high dielectric constant, excellent stiffness, superior mechanical strength, and high corrosion resistance, glass fiber reinforced polymer nanocomposites are considered as promising insulating materials in power apparatus, along with automotive, aerospace, wind energy harvesting, and marine applications [10,11,12]. By considering the aspects above, the following methodical experimental experiments were performed to investigate the influence of MgO nanoparticles on glass fiber reinforced epoxy material: (i) Surface discharge and corona inception studies; (ii) Surface potential and trap characteristics under switching impulse (SI) voltages; (iii) Space charge analysis under voltage polarity reversal phenomenon; (iv) Thermo gravimetric analysis; and (v) Determination of the thermal expansion coefficient. When the filler content was increased to 5%, non-uniform submicron agglomerations occurred, which could potentially have a poor impact with the interlinking of the nanoparticles with the polymer matrix and the glass fiber
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