Eva copolymer-based nanocomposites: Rheological behavior under shear and isothermal and non-isothermal elongational flow

Nanocomposites are a very promising new class of polymer composites that exhibit an interesting combination of chemical, physical and mechanical properties. Only small amounts of nanofiller are sufficient to generate great variation of many properties. This work focuses on the rheological properties of poly[ethylene-co-(vinyl acetate)] (EVA copolymer) based nanocomposites in shear and in isothermal and non-isothermal elongational flow. The nanocomposites, at two different filler contents, were prepared in two different extruders and intercalates were obtained for all the samples. The twin-screw compounder is more efficient. The change of rheological properties, both in shear and in elongational flow, with respect to the pure matrix seem to follow the change of interlayer distance of the silicate particles. The nanocomposites, however, present, in the usual processing conditions, rheological properties similar to those of the virgin polymer, making possible their use in processing operations where both shear and elongational flows are involved. (C) 2006 Published by Elsevier Ltd.