Enhanced Performance of Aramid/Epoxy Composites by Silane Coupling Treatment of Fillers

Epoxy (EP) resin is widely used in the field of electrical insulation. Different fillers can affect the performance of EP resin in different aspects. In this work, dopamine and silane coupling agents were adopted to treat aramid fiber powder (AP). The untreated AP and treated AP (KH560-dopamine (KD)-AP) were formed into a composite with EP resin. The trap distribution, breakdown strength, volume conductivity, and elastic modulus of aramid fiber/EP composites were fully investigated. AP doping leads to serious interface defects. The breakdown strength of KD-AP-EP increased by 39% compared with that of AP-EP. Surface potential decay (ISPD) was adopted to measure the carrier trap characteristics, and the addition of KD-AP leads to an increase in deep traps within the composites, which helps to reduce the number of migrating charges, resulting in a lower interface charge attenuation rate and volume conductivity. KD-AP-EP can also obtain higher elastic modulus with lower dosage.