UP/ bentonite nanocomposites: influence of clay modification on final performance

ROMINA OLLIER; VERA ALVAREZ; EXEQUIEL RODRIGEZ

Los Cocos

Congreso; V Archipol: Simposio Argentino-Chileno de Polímeros; 2009

For decades, polymeric materials have been reinforced in order to improve different properties such as mechanic, thermal and impact resistance, or to decrease others such as electric conductivity, gas permeability, depending on the application (Alexandre at al 2000). In most of the cases, surface interaction between both components is not strong enough. On the other hand, the elements of microscopic reinforcement generally have imperfections. Structural perfection improves if these elements are smaller: it is believed that the last properties of the reinforcement will be achieved if there were of molecular size order. Clay particles, which are about 1 nanometer thick, have a perfect crystalline structure. However, the smaller these reinforcement elements are, the larger internal surface will be, and consequently its tendency to agglomerate in a matrix, than to disperse homogenously (Hartmut 2003).. Among these reinforcements, the use of bentonite is interesting because beyond to the environmental and economic factors, their natural abundance, and their mechanical and chemical resistance makes them very useful as polymeric material reinforcements. In order to achieve better properties it is necessary to obtain a totally exfoliated structure (this means that the silicate layers are completely and uniformly dispersed in a continuous polymeric matrix) but the tendency of the particles to agglomerate has been difficult to overcome. What’s more, most of the polymers are hydrophilic, so it is necessary to make a previous treatment to the clay or to the polymer so as to make them more compatible (Hedley et al2007; Bala et al 2000). The main objective of the present work was to analyze the effect of chemical modification of bentonite on the final performance of UP (unsaturated polyester)/bentonite nanocomposites.