AVVISO di SEMINARIO

Il giorno 16 Ottobre 2003, giovedì, alle ore 15.00 presso la Biblioteca del Dipartimento di Ingegneria Chimica, Mineraria e delle Tecnologie Ambientali, il

prof. Donald R. PAUL,

professore di Ingegneria Chimica e direttore del Department of Chemical Engineering and Texas Materials Institute, University of Texas at Austin,

membro della National Academy of Engineering (USA), in visita presso il Dipartimento, terrà un seminario sul tema:

Properties of Well-Exfoliated Polymer/Clay Nanocomposites: Comparison of Experiment with Theory

E’ gradita la partecipazione di tutti gli interessati.

~~ ٠ ~~ ~~ ٠ ~~

Summary

Polymer-layered silicate nanocomposites formed from the organically modified clay mineral montmorillonite and related materials have attracted a great deal of technological and scientific interest owing to the promise of greatly improved properties over those of the matrix polymer compared to what can be achieved with conventional fillers. This presentation focuses on two issues: how to achieve high levels of dispersion of the one nanometer thick, high aspect ratio aluminosilicate layers and to what extent the resulting benefits can be explained by conventional composite theories. In essence, the latter raises the question of whether there is an effect of the high surface area, nanoscale filler on the matrix polymer or not, i.e., is there a "nano-effect."

Nylon 6 is used as a model matrix for a variety of reasons. The factors that must be addressed to achieve high levels of platelet exfoliation in this matrix by melt processing will be summarized. The rich morphology of the resulting nanocomposites has been characterized in detail by transmission electron microscopy. Experimental data for tensile stress-strain, dynamic mechanical, and thermal expansion behavior as a function of clay content and degree of exfoliation will be presented. Finally, these properties will be compared to the theories of Halpin-Tsai and Mori-Tanaka (also Chow) in an attempt to answer the question of whether there is a "nano-effect" or not.