Hebei Messi Biology Co., Ltd. stated that EVA (ethylene-vinyl acetate copolymer) is widely used in flame-retardant cable materials due to its good electrical properties, chemical stability, processing performance and good compatibility with fillers. Magnesium hydroxide is an environmentally friendly inorganic flame retardant and a halogen-free flame retardant that is more suitable for EVA. EVA/Mg(OH)2 composite materials must meet certain insulation performance requirements when used in an electric field environment. In the case of high filling of magnesium hydroxide, the interface of each component of the composite material is affected by the filler, filling amount and surface modification. has a great influence, which will inevitably lead to changes in the dielectric properties of composite materials. Therefore, studying the influence of composite material components on dielectric properties is of great significance in both theory and application.
In this paper, matrix resin samples were prepared and their dielectric properties were tested. An orthogonal experimental design was used to study the relationship between various factors and the dielectric properties of composite materials. VA content, magnesium hydroxide addition, and compatibilizer addition were selected as factors in the orthogonal experiment. Four levels were selected for each factor. , the first three columns of the L16(45) orthogonal table were used to formulate the experimental orthogonal table. The surface of magnesium hydroxide was modified with the same quality of epoxy silane and stearic acid respectively. Two groups of samples were prepared according to the orthogonal table, and the dielectric properties of the samples before and after aging were tested: dielectric constant, Dissipation factor, breakdown strength and volume resistivity at different temperatures.
Research results show that with the increase of VA content, the dielectric constant and loss factor of the matrix resin gradually increase, and the volume resistivity gradually decreases; the dispersion of breakdown strength decreases with the increase of VA content. Composite material dielectric property test results show that VA content is the most critical factor affecting the four dielectric performance parameters. As the VA content increases, the dielectric constant and loss factor increase, and the volume resistivity and breakdown strength decrease.