Synthesis of epoxy-clay nanocomposites. Influence of the nature of the curing agent on structure

Epoxy-clay nanocomposites were synthesised by swelling an organophilic mont morillonite in a diglycidyl ether of bisphenol A resin with subsequent poly merisation. Three different curing agents were used: an aliphatic diamine a nd two cycloaliphatic diamines. The cure kinetics of these systems was eval uated by differential scanning calorimetry and the structure of the nanocom posites was characterised by X-ray diffraction and transmission electron mi croscopy. Successful nanocomposite synthesis was dependent not only on the cure kinetics of the epoxy system but also on the rate of diffusion of the curing agent into the galleries because it affects the intragallery cure ki netics. The nature of the curing agent influences these two phenomena subst antially and therefore the resulting structure of the nanocomposite. The cu ring temperature controls the balance between the extragallery reaction rat e of the epoxy system and the diffusion rate of the curing agent into the g alleries. Thus, the choice of curing agent and curing conditions controls t he extent of exfoliation of the clay in the material. (C) 2001 Elsevier Sci ence Ltd. All rights reserved.