Transmission electron microscopy study of room temperature cured PMMA grafted natural rubber toughened epoxy/layered silicate nanocomposite

A morphological study was conducted on ternary systems containing epoxy, poly(methyl methacrylate) grafted natural rubber and organic chemically modified montmorillonite (Cloisite 30B), using TEM. The following four materials were prepared at room temperature: cured unmodified epoxy, cured toughened epoxy, cured unmodified epoxy/Cloisite 30B nanocomposites and cured toughened epoxy/Cloisite 30B nanocomposites. Mixing process was performed by mechanical stirring. Poly(etheramine) was used as the curing agent. The detailed TEM images revealed cocontinuous and dispersed spherical rubber in the epoxy-rubber blend, suggesting a new proposed mechanism of phase separation. High magnification TEM analysis showed good interactions between rubber and Cloisite 30B in the ternary system. In addition, it was found that rubber particles could enhance the separation of silicate layers.