Effect of alumina shapes on dielectric properties of UV-cured epoxy acrylic composite with alumina

Polymer-based composites with the advantages of ceramics and polymers exhibit high dielectric constant, good processing properties and low dielectric loss. The composites with a varied content of irregular alumina (i-Al2O3) filler were prepared by UV-cured epoxy acrylic (EA). Spherical alumina (s-Al2O3) was used as a filler to further investigate the effect of alumina (Al2O3) shapes on dielectric properties of composites in the frequency range of 50 Hz-1 MHz. Fourier transform infrared spectroscopy proved that the UV-cured epoxy acrylic/alumina (Al2O3/EA) composites were successfully fabricated. Scanning electron microscopy demonstrated that i-Al2O3 particles have superior homodispersion in the matrix. Through testing, for all samples, with the addition of Al2O3, the relative permittivity of composites increased as expected, and the dielectric loss decreased accordingly. These data show that the incorporation of i-Al2O3 particles presents better properties when compared with s-Al2O3/EA, which indicates that i-Al2O3 particles have more influence on the dielectric properties of the composites than those of s-Al2O3 particles. According to Weibull distribution, the characteristic breakdown strength of the Al2O3/EA composites was obtained and the results suggested that the composites of i-Al2O3/EA exhibited better breakdown performance.