About the Influence of Particle Size on Thermal Properties Investigated by Means of Thermal Analysis

Reference	Presenter	Authors (Institution)	Abstract
16-051	Ekkehard Füglein	Füglein, E.(NETZSCH-Gerätebau GmbH); Wolff-Fabris, F.(European Center for Dispersion Technologies);	When thinking about solid state kinetics, the active species of chemical reactions, catalytic effects or the mechanism of solid state reactions, the surface of particles turns out to be of significant importance. Surprisingly enough, the influence or variation of particle size is very often neglected. Just recently the parameter of particle size started to gain in importance and is nowadays more often considered as important parameter for specification of raw materials in particular for industrial production processes. Even though thermal analysis techniques can neither directly determine particle size nor image particles, thermal behavior of macroscopic samples are still strongly influenced by the active particle surface. As a consequence, thermal analysis techniques such as differential scanning calorimetry (DSC), thermogravimetry (TG), and dilatometry (DIL) can be used in order to study the influence of particle size on thermal properties. By means of various reaction types such as decomposition, pyrolysis and dehydration, the present work describes thermal behavior of inorganic materials by taking the aspect of particle size into account. The decomposition of inorganics, the dehydration of inorganic pigments and the sintering behavior are investigated for samples of different particle sizes produced by grinding using an agitator bead mill. The dehydration reaction of aluminum hydroxide (Al(OH)3) absorbs a considerable amount of energy at reasonably low temperature (~200°C) and additionally delivers three moles of water per two moles of aluminum hydroxide. That’s why Al(OH)3 is well known and widely used as flame retardant agent. As reported earlier for other dehydration reactions, also this work will show, that thermogravimetry (TG) is a sensitive analytical tool to study parameters such as particle size as well as dispersion quality in a medium.
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