Cryogenic mechanical and electrical properties of polyimide nanocomposites

Polyimide (PI) nanocomposite films that possess high strength and modulus, good ductility and electrical properties are desirable in cryogenic engineering applications such as in superconductor systems. In this paper, PI nanocomposite were prepared by incorporating organo-clay into PI matrix. Mechanical and electrical properties of the PI nanocomposite with different amount of filler content were studied at cryogenic temperatures (77K) and compared with those at room temperature. When measured at 77K the tensile strength and modulus of these films are obviously higher, and the elongation at break is lower than those measured at room temperature. Moreover, for the films with low clay content (1 to 5 wt%), the elongation at break was above 10% at 77 K. This shows acceptable levels of ductility of the films at 77K. The electrical breakdown strength of PI nanocomposite films ranged from 150 kV/mm to 220 W/mm at 77K.