Effect of silane coupling agent KH550 on the dielectric properties of CaCu3Ti4O12/polyurethane composite films

Flexible CaCu3Ti4O12 (CCTO)/polyurethane dielectric composite films were fabricated, and the effects of the silane coupling agent, 3-Aminopropyltriethoxysilane (KH550), on the dielectric properties of the composite films were investigated. It was found that using KH550 significantly improved interfacial compatibility between the CCTO filler and the polyurethane matrix, leading to the reduction of dielectric loss and conductivity, and an increase in the dielectric breakdown strength. At 100 Hz, the composite film with a 3 wt% KH550 dosage exhibited a dielectric constant of 53.1 and a dielectric loss of only 0.068 (a 73.8 % reduction compared to the composite film with untreated CCTO particles). The composite films with KH550-modified CCTO particles exhibited a maximum breakdown strength of 18.5 kV/mm, showing a 58.1 % increase compared to the composite film with untreated CCTO particles. Moreover, introducing KH550 was beneficial in reducing the variation of dielectric properties with temperature, thereby enhancing the reliability of polyurethane based dielectric composite materials in practical applications.