Evaluation of the physico‐chemical properties of an amorphous magnesium silicate synthesized by an ultrasound‐assisted 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. Good dispersion in a polymer matrix requires fine particles, of nanometric size that are easy to disperse. However, at the moment the main drawback in the use of natural talc is that, with a conventional milling process, nanometric particle sizes are difficult and expensive to obtain. The objective of this study is to develop a process of magnesium silicate synthesis made by precipitation. This step is the first in the manufacturing process of synthetic talc. This study examines the influence of different process parameters on product properties (the way the reactants are added, the reactants themselves, molalities and ultrasound). The synthesized product is highly agglomerated, whatever process parameters are used, but the use of some specific parameters could result in a reduction in the size of the agglomerates. The addition of reactants by a mixing system with ultrasound during the synthesis could be the best method to synthesize the smallest particles. Moreover initial reactant molalities influence the nucleation rate and thus the agglomeration phenomenon. But initial reactant molalities also have an effect on solid purity. Amorphous silica can co‐precipitate with magnesium silicate in some molality ranges.
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