Preparation and morphological, electrical, and mechanical properties of polyimide‐grafted MWCNT/polyimide composite

Abstract

Abstract Precursor of polyimide, polyamic acid has been prepared sucessfully. Acid‐modified carbon nanotube (MWCNT) was grafted with soluble polyimide then was added to the polyamic acid and heated to 300 °C to form polyimide/carbon nanotube composite via imidation. Morphology, mechanical properties and electrical resistivity of the MWCNT/polyimide composites have been studied. Transmission electron microscope microphotographs show that the diameter of soluble polyimide‐grafted MWCNT was increased from 30–60 nm to 200 nm, that is a thickness of 70–85 nm of the soluble polyimide was grafted on the MWCNT surface. PI‐ g ‐MWCNT was well dispersed in the polymer matrix. Percolation threshold of MWCNT/polyimide composites has been investigated. PI‐ g ‐MWCNT/PI composites exhibit lower electrical resistivity than that of the acid‐modified MWCNT/PI composites. The surface resistivity of 5.0 phr MWCNT/polyimide composites was 2.82 × 10 8 Ω/cm 2 (PI‐ g ‐MWCNT) and 2.53 × 10 9 Ω/cm 2 (acid‐modified MWCNT). The volume resistivity of 5.0 phr MWCNT/polyimide composites was 8.77 × 10 6 Ω cm (PI‐ g ‐MWCNT) and 1.33 × 10 13 Ω cm (acid‐modified MWCNT).Tensile strength and Young's modulus increased significantly with the increase of MWCNT content. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3349–3358, 2007