The effect of nanoparticle inclusion on the tensile and mode I fracture properties of polyimides

Polyimide nanocomposites were fabricated using a combination of rotation/revolution mixing, layer-by-layer deposition and autoclave curing techniques. Seven different types of nanoparticles (25 nm C, 20–30 nm β-SiC, 130 nm β-SiC, 10 nm SiOx (x = 1.2–1.6), 80 nm SiO2, 11 nm γ-Al2O3 and 40–80 nm γ-Al2O3) and four different particle volume fractions (0.5, 1, 5 and 10 vol%) were used for the inclusion. fect of nanoparticle inclusion on the tensile properties and mode I fracture toughness was also investigated. The tensile modulus of the nanoparticle-filled polyimides was improved by the nanoparticle inclusion and increased with increasing volume fraction of the nanoparticles. No large differences in the tensile strength were observed for the nanoparticle-filled and unfilled polyimides. The mode I fracture toughness of the nanoparticle-filled polyimides was improved by C, β-SiC, SiOx (x = 1.2–1.6), SiO2 and γ-Al2O3 nanoparticle inclusion and the maximum mode I fracture toughness, indicated by the critical stress intensity factor, was observed at approximately 5 vol% nanoparticle content for each type of nanoparticle-filled polyimide.