Modeling nanoclay effects into laminates failure strength and porosity

The effect of nanoclay presence into epoxy based fiber glass composites was investigated. It was demonstrated the existence of a saturation limit, around 5%, for such nanocomposites. XRD analysis indicates that these nanocomposites are composed mostly by intercalated nanostructures. To be able to correlate the fracture stress and the laminate porosity, a modification of the Mar–Lin failure criterion was proposed. Good agreement to experimental data was obtained when the proposed criterion was applied into the fracture stress prediction as a function of the void content. A decrease on void formation, around 77%, was obtained with the usage of nanoclay in small quantities (up to 10% with respect to the matrix weight). The void content reduction seems to be the result of a highly exothermic chemical reaction between the nanoclay, hardener, acetone and the resin itself, with consequent the gel time reduction around 30%. These two factors can be related to the changes into polymerization process due to the nanoclay presence.