Clay-Reinforced Epoxy Nanocomposites: Synthesis, Properties, and Mechanism of Formation

Abstract

Epoxy-clay nanocomposites have been synthesized by exfoliation of organoclays during the epoxy thermosetting process. The extent of silicate layer separation is governed by the chain length of gallery cations, the clay layer charge density and the acidity of the gallery cations. By using different curing agents, we obtained both glassy and rubbery epoxy matrices. Reinforcement was substantially greater for the rubbery matrix. Both the tensile strength and the modulus of the rubbery epoxy-clay nanocomposite increased with increasing clay content. The reinforcement provided by the silicate layers at 15 wt% loading was manifested by a more than ten-fold improvement in tensile strength. The rubbery state of the matrix may allow alignment of the exfoliated silicate layers upon applying strain, thereby enhancing reinforcement.