Abstract
This article reports on the development of nano-MgO/epoxy resin composites with various mass ratios via a solution blending method. The influence of MgO nanofillers on the thermal properties and the effect of environmental temperature on the insulating properties of the composite material were analyzed. The results show that the thermal conductivity of the composites increased with an increasing MgO nanofiller content. Compared with the pure epoxy resin, the thermal conductivity increased by 75% when the content of MgO nanoparticles was 7%. The volume resistivity first increased and then decreased with an increasing doping concentration. The volume resistivity increased by 26.8% in comparison with the pure epoxy resin when the content of MgO nanoparticles was 1%, while its dielectric constant and dielectric loss increased with temperature. In addition, the dielectric constant increased and the dielectric loss first decreased and then increased with an increasing MgO nanoparticle content. Moreover, the MgO composites changed from a glassy to a rubbery state, and the breakdown strength was significantly reduced with an increased temperature. When the temperature was higher than the glass transition temperature, the breakdown strength decreased by 51.3% compared with the maximum breakdown strength at 20 °C. As the content of MgO nanoparticles increased, the breakdown strength of the composite first increased and then decreased. The highest breakdown strength was achieved when the content of MgO nanoparticles was 1%, which was 11.1% higher than that of the pure epoxy resin. It was concluded that the MgO nanofillers can significantly improve the thermal properties of epoxy composites and their insulation performance at high temperatures.
Highlights
Epoxy resins are widely used in electronics due to their good electrical, thermal, and processing properties, being one of the main materials used in electrical equipment [1,2]
Studies have demonstrated that the thermal conductivity, dielectric, breakdown, and other main electrical properties of epoxy resins can be improved by doping with different kinds of nanoparticles, such as silicon dioxide, titanium dioxide, aluminum oxide, and magnesium oxide, among others
Π(d1 + g)2 ε0 where C is the capacitance of the sample, h is the thickness, d1 is the diameter of the protected electrode, g is the electrode gap, and ε0 is the dielectric constant of the vacuum
Summary
Epoxy resins are widely used in electronics due to their good electrical, thermal, and processing properties, being one of the main materials used in electrical equipment [1,2]. Studies have demonstrated that the thermal conductivity, dielectric, breakdown, and other main electrical properties of epoxy resins can be improved by doping with different kinds of nanoparticles, such as silicon dioxide, titanium dioxide, aluminum oxide, and magnesium oxide, among others. Nelson et al investigated the dielectric performance of nanotitanium dioxide epoxy resins, demonstrating that nanofillers can reduce the interface polarization characteristics of traditional materials and reduce the accumulation of internal electric fields [18]. Maezawa et al studied the space charge behavior of LDPE/nano-MgO composites containing MgO particles of different particle sizes at a high temperature and electric field. The influence of temperature on the electrical performance of nano-MgO/epoxy composites (epoxy-h-BN composites) with different mass fractions, including the dielectric performance and breakdown performance, was studied
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