Catalytic charring-volatilization competition in organoclay nanocomposites

The thermal behaviour of organoclays, and especially their organic treatment, is an important issue in polymer nanocomposite preparation and their fire retardant properties. The thermal behaviour of the organomodifier is strongly affected by the different composition parameters of the clays. Thus the thermal degradation, in inert and in oxidative atmosphere, of natural montmorillonite and synthetic fluorohectorite both exchanged with polar and non-polar organomodifiers was studied using a combined thermogravimetry/Fourier transform infrared and a flash pyrolysis GC-MS system. Decomposition and charring mechanisms of the organic molecules in the clays are proposed for each kind of clay and a relationship between the composition of the clays and the kinetics of the decomposition reactions is found. Furthermore, it is shown that the charring-volatilization competition on heating organoclays in the presence of oxygen depends on the structure of the clay, the confined or unconfined position of the organic molecules and their polarity. (c) 2006 Elsevier Ltd. All rights reserved.