Effect of Different Matrices and Nanofillers on the Rheological Behavior of Polymer-Clay Nanocomposites

Abstract

In this work, a comprehensive study of the rheologi-cal behavior under shear and isothermal and nonisothermal elongational flow of low density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) based nanocomposites was reported to evaluate their "filmability", that is, the ability of these material to be processed for film forming applications. The influence of two different kinds of organoclay - namely Cloisite 15A and Cloisite 30B - and their concentration was evaluated. The presence of filler clearly affects the rheological behavior in oscil-latory state of polyolefin-based nanocomposites but the increase of complex viscosity and the shear thinning are not dramatic. A larger strain-hardening effect in isothermal elongational flow is shown by the nanocomposites compared to that of the pure ma-trix, particularly for EVA based nanocomposites. The melt strength measured under nonisothermal elongational flow increases in the presence of the nanofiller, while the drawability is only slightly lower than that measured for the neat matrix. Moreover, the rheological behavior under nonisothermal elon-gational flow of EVA-based nanocomposites is similar for both nanoclays used. Differently, LDPE-based nanocomposites show a strong dependence on the type of organoclay. Finally, the me-chanical properties of the materials were measured by tensile tests. They revealed that the presence of the filler provokes, in all the cases, an increase of the rigidity.