Study effect of the thickness and the periodic loading on the dielectric strength for ( polyester – Nanoceramic )

Abstract

This paper includes some factors that effect on the dielectric strength of unsaturated polyester resin which supported by alumina by weight fracture (4%). the samples prepared by casting cold method with thickness about (1.5)mm to (4)mm .the results shows that the dielectric strength decreased when the thickness increased and that is more clear at high thicknesses. but the effect of periodic loading on the dielectric strength of the composite. We notice sharp decrease in the dielectric strength of the composite for all different thicknesses. the microscope pictures of the break down area that taken by optical microscope shows the coaling of the breakdown area of the samples .