Research article

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Nanocomposites were prepared using an ethylene vinyl acetate copolymer (EVA) and organically modified Cloisite® 93A clay in the absence and presence of dicumyl peroxide (DCP) and dibenzyl peroxide (DBP) as cross-linking agents. The results clearly show differences in the EVA-clay morphology of nanocomposites prepared in the absence of organic peroxides, and of those prepared in the presence of respectively DCP and DBP. It seems as if DCP may initiate grafting between the polymer and the clay, which results in an exfoliated morphology. The presence of clay seems to inhibit the initiation of EVA crosslinking by the DBP free radicals. These free radicals probably initiate hydroxylated edge-edge interaction between the clay layers, which gives rise to a flocculated morphology and reduced polymer-clay interaction. There is a good correlation between these morphologies and the thermal stabilities and total crystallinities of the nanocomposites. Clay incorporation and peroxide treatment did not significantly change the tensile properties.