Dynamic mechanical analysis of fumed silica/cyanate ester nanocomposites

Fumed silica particles with average primary particle diameters of 12 and 40 nm were combined with a low viscosity bisphenol E cyanate ester resin to form composite materials with enhanced storage modulus and reduced damping behavior, as evidenced by dynamic mechanical analysis (DMA). The storage modulus increased with volume fraction of fumed silica in both the glassy and rubbery regions, but the increase was more pronounced in the rubbery region. The maximum increase in storage modulus in the glassy region was 75% for 20.7 vol% of 40 nm fumed silica, while the same composition showed a 231% increase in the rubbery storage modulus. Furthermore, decreases in damping behavior were used to estimate the effective polymer-particle interphase thickness. The glass transition temperature of the nanocomposites was not changed significantly with increasing volume fraction.