Effects of coupling agents on structure and properties of polyimide/Al₂O₃ nanocomposite films

Abstract

Purpose The purpose of this paper is to investigate the effects of coupling agents on the structure and properties of the nanocomposite films and clarify their mechanism. Polyimide (PI)/Al 2 O 3 nanocomposite films were prepared using different coupling agents. Design/methodology/approach Poly(amic acid) (PAA) was firstly synthesised from appropriate pyromellitic diannanocomposite and oxydianiline in N‐dimethylacetamide. Calculated amount of nano‐Al 2 O 3 particles modified by different coupling agents (KH550, KH560, KH570 and AE3012) were added to PAA solution by an ultrasonic‐mechanical method and PI/nano‐Al 2 O 3 film was fabricated by heat curing. The microstructure, thermal stability, mechanical properties and electric breakdown strength of the films were characterised. Findings The addition of coupling agents could greatly improve the dispersion homogeneity of Al 2 O 3 nano‐particles in PI matrix. Results of corresponding characterisations indicated that both the thermal stability and mechanical properties of PI/Al 2 O 3 nanocomposite film with KH550 were greater/better than others, while AE3012 could improve the electric breakdown strength. Research limitations/implications In the present discussion, the effects of different coupling agents, KH550, KH560, KH570 and AE3012, were investigated. Results of this research work would be beneficial to an in‐depth understanding on the relationship between microstructure and properties of PI composites, and further promote the development of the high‐performance PI insulating materials. Originality/value The four coupling agents, KH550, KH560, KH570 and AE3012, were firstly used to disperse the nano‐Al 2 O 3 particles in PI matrix. The effects of coupling agents on microstructure and properties of composites were discussed by the authors in detail.