The effects of coupling agents on the properties of polyimide/nano-Al2O3composite films

Polyimide/nano-Al₂O₃composite films based on Pyromellitic diancompositee (PMDA) and 4,4´-Oxydianiline (ODA) were prepared by ultrasonic-mechanical method. Before addition, nano-Al₂O₃particles were firstly modified by coupling agent DB550. The morphology and properties of composite films with different contents of DB550 were investigated. Results indicated that the addition of coupling agent and its weight content had a remarkable effect on the microstructure, and electric breakdown strength of composite films. Scanning electron microscopy (SEM) images showed that nano-Al2O3 particles were relatively well dispersed in the polyimide matrix after the addition of coupling agent. When the content of coupling agent DB550 was 2 wt%, the electric breakdown strength of PI/nano-Al₂O₃composite films was the best and when the content of coupling agent DB550 was 3 wt%, the mechanical properties of PI/nano-Al₂O₃composite films were the best.