Processing of iron oxide-epoxy vinyl ester nanocomposites

An ultrasonic method is used to disperse iron oxide particles of two different sizes in an epoxy vinyl ester resin. The dispersion quality is assessed from sedimentation, density measurements, and scanning electron micrographs. By varying parameters such as power and duration of sonication, optimum dispersion conditions are suggested. Dispersion is most effective in the early stage of sonication and becomes more difficult to improve later. Once separated, however, the particles do not come into direct contact with one another because of the steric hindrance. The nano-size (29 nm) particles delay curing whereas the larger (200 nm) particles do not. The results indicate a strong interaction between nanoparticles and the resin.