1. High Temperature and Flammability Behavior of Nanocomposites and Polymer Blends Menachem Lewin (Polytechnic University) DMR-0352588 The work in the first stage of the project concentrated on the high temperature behavior of nanocomposites; an area which was hitherto only slightly explored. The temperature stability of the nanocomposite and changes occurring in its structure and composition during aging, heating, annealing, and air oxidation were investigated. The study revealed the stability limits of the nanocomposites under changing conditions brought about by the 3 basic forms in which the blends of polymers with organo-layered silicates can exist or co- exist. Annealing studies of the nanocomposites at a range of temperatures shed new light on the processes occurring in the intricate structure of the layered alumino-silicate composites. The interplay between the properties of the organo-surfactants linked to the alumino-silicate layers, and the hydrophobicity and polarity of the polymers presents a highly interesting and involved microcosm in which a series of chemical and physico-chemical processes take place. Of particular interest is the effect of the gradual decomposition of the organic surfactant on the behavior of the nanocomposite. Annealing at high temperatures of a polypropylene nanocomposite brings about the decomposition of the surfactant and a conversion of the nanocomposite structure into a macro-composite structure. Annealing at lower temperatures, especially in the presence of limited amounts of air, enhances the migration and accumulation of the mineral clay particles on the surface of the polymer, thus creating an asymmetric structure and distribution of the mineral particles. This migration phenomenon, which we were the first to assume, has now been conclusively confirmed and demonstrated. It occurs already at relatively low temperatures of below 200°C. Top/Bottom Clay Content Ratio for 5% Nanocomposites as Determined by FT-IR ATR Spectroscopy.

2. High Temperature and Flammability Behavior of Nanocomposites and Polymer Blends Menachem Lewin (Polytechnic University) DMR-0352588 A literature survey was made on the Surface Free Energies of polymer additives and clays. The survey was published in the June 2005 issue of Journal of Polymers for Advanced Technologies (Vol 16, 6 429-441). It was prepared in view of the growing interest in the properties and performance of nanocomposites, and is intended to guide students and researchers in the application of thermodynamic principles in the technology of nanocomposites. The properties and behavior of polymer nanocomposites was hitherto largely investigated at ambient temperatures, and only little is known about the structure, stability, and behavior of nanocomposites at elevated temperatures. We discovered in this study that at temperatures higher than 250°C, the structure of the nanocomposite changes and behaves like a normal composite material. On the other hand, it was discovered and demonstrated that the mineral ingredient (ie: clay particles) migrate to the surface of the heated polymer, and form a protective mineral barrier, already at temperatures below 200°C. This is of considerable importance for several ranges of applications: including preparation of flame- resistant structures for computer cases, cables, and electronics. The present study may also throw light on the effect of high- temperature treatments on the mechanical, physical, and thermal properties of the nanocomposites, and their performance in use conditions. A better understanding of the aging of nanocomposites and their effect of the performance on various applications may also be gained.