Solvent Uptake of Liquid Rubber Toughened Epoxy/Clay Nanocomposites

Carboxyl-terminated poly (butadiene-co-acrylonitrile) (CTBN) liquid rubber toughened epoxy (epoxy/CTBN blend) and CTBN-toughened epoxy/clay nanocomposites (epoxy/clay/CTBN nanocomposites) were prepared, and solvent (acetone) uptake was studied as a function of CTBN content. It was found that in both epoxy/CTBN blend and epoxy/clay/CTBN nanocomposites, the diffusion coefficient initially increased with an increase in CTBN content, with a maximum value registered for the systems containing 15 phr of CTBN. With a further increase of CTBN, the diffusion coefficient was found to decrease. The variation of solvent uptake with CTBN content depends on both the amount of dissolved rubber in the epoxy phase and the phase morphology associated with each composition. The high acetone uptake in 15 and 20 phr CTBN-loaded system was found to be reduced dramatically by the incorporation of 3 phr nanoclay. Owing to the presence of high aspect ratio clay platelets, the diffusion of acetone undergoes a more tortuous path in epoxy/clay/CTBN nanocomposites than in epoxy/CTBN blends. A diffusion mechanism correlated to composition for epoxy/CTBN blend and epoxy/clay/CTBN nanocomposites was proposed.