Dielectric Properties of the Modified Epoxy Resins by Polyester
Cao Youming,Sun Jun
(Xi'an Jiaotong University, Xi'an 710049, China)

Abstract: The modified epoxy resins by polyester (PET), which is prepared by a blending process, have excellent dielectric properties. Their dielectric loss is of the order of 0.001 in magnitude at roomtemperature. The relationships of the composition,frequencies of electric field,testing temperature and dielectric loss, and effects of adding PET on the dielectric constant and elastic modulus are investigated. Experimental results show that the dielectric loss depends on the addition of PET,frequencies of electric field and testing temperature. The elastic modulus of composites is higher than that of the pure epoxy resin. Dielectric loss decreases with increasing frequency of the electric field. A peak phenomenon is found with the addition of PET. A sharp enhancement appears when the testing temperature is increased beyond 150 degrees centigrade.
Keywords: epoxy resin;polyester;dielectric properties