The Interactions of Silane and Zirconate Coupling Agents with Calcium Carbonate

Abstract

The present work deals with the study of the structure and the form of the deposit on calcium carbonate of two types of silane coupling agents and a zirconate one. The structure of the deposited layers as well as their interactions with the filler were investigated by means of Fourier Transform Infra-Red Spectroscopy. The extent of the recovery was determined using the dissolution method, which allowed the authors to measure the adsorbed quantity and to estimate the molecular area occupied by each coupling agent as well as the orientation of the molecules on the surface of CaCO3. The structure of the aminosilane layers deposited on calcium carbonate appeared to be greatly influenced by the initial conditions of treatments. These include the pH, the concentration of the aqueous bath of impregnation, duration, and method of application. The results showed the formation of structures polymerized on the surface of CaCO3 and the deposit was composed of monomers and oligomers that were both physisorbed and chemisorbed. The study of the chemical structure of the zirconate agent that was deposited on the surface of CaCO3 showed that a monomolecular layer was chemically adsorbed. The physisorbed part was mainly constituted of monomers that were soluble in the solvent used for the extraction.