Strategies for Improving the Performance of Polimeric Matrix/Clay Nanocomposites

LEANDRO N. LUDUEÑA; VERA A. ALVAREZ

Advances in Nanotechnology

Nova Science Publishers, Inc.

Lugar: Nueva York; Año: 2014; p. 31 - 42

In this work several strategies were used to obtain well-dispersed and, so that with improved mechanical properties, nanocomposites. The strategies are based on the chemical modification of the clay and on the variation of processing conditions. The clay dispersion was characterized by wide angle X-ray diffractometry (XRD), transmission electron microscopy (TEM) and melt rheology (that was used as a novel method to study the morphology of polymer/clay nanocomposites). It was found that the final clay content and clay dispersion degree inside the nanocomposite were the key factors, demonstrating that polymer-clay compatibility is not the only condition required to achieve the best mechanical performance when shear forces induced during processing, in techniques such as extrusion, are used to prepare the polymer/organo-modified clay nanocomposite. The effect of changing processing parameters (temperature, speed of rotation of the screws and residence time) on the morphology and mechanical properties of polymer/clay nanocomposites was also studied . Different processing techniques, such us stretching and injection molding, compression molding, were also analyzed and the effect of each one on the final properties of nanocomposites were determined. It was shown that the variation of extrusion parameters not always has significant influence on the final properties of the nanocomposite, which is mainly related with the fact that the critical step for obtaining a high degree of dispersion of reinforcement within the matrix is the optimization of a balance between the polymer/clay chemical compatibility and the thermo-mechanical stability of the clay organo-modifier. Finally, it was shown that using certain processing techniques in which different fluid regions are subjected to extensional flow, the clay particles can be oriented preferentially in that direction improving the mechanical properties of the nanocomposite.