Properties of an amorphous magnesium silicate synthesized by precipitation
Résumé
Natural talc is a very interesting filler for plastic and rubber materials and paints because it improves their properties by delivering mechanical reinforcement and barrier effects. A good dispersion in a polymer matrix involves fine particles, with a size in the order of nanometer. But at the moment the main drawback of the use of natural talc is that, with conventional milling process, particles size under one micrometer are difficult and expensive to obtain. This study objective is to develop a process of magnesium silicate synthesis made by precipitation. This step is the first in the manufacturing process of synthetic talc. The resultant product will have properties that are not possible to obtain with the milling process , in particular particle size smaller than one micrometer. The influence of different process parameters (reactants' addition mode, reac-tants' concentrations, synthesis temperature and ultrasound) on product properties is studied. Synthesized product is very agglomerated whatever process parameters but some parameters would enable to decrease agglomerates size. Reactants' addition by a mixing system with ultrasound during the synthesis would be the best in order to synthesize smallest particles. Moreover synthesis temperature and initial reactants' concentrations influence the nucleation rate and so agglomeration phenomenon.
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