“A new approach on the Preparation of Coated Clays using Silanes as Modifiers”

FERNANDA MONASTERIO, MARCOS L. DIAS, VICTOR J.R.R. PITA, HUGO DESTÉFANIS, ELEONORA ERDMANN, NADIR DE BRITOS SANCHES

Rome,Italy.

Congreso; Nanofun-Poly 2008; 2008

Different paths could be taken in the aim of improving polymers behavior. In particular, in the last decades, the addition of nanometric solids into the polymeric matrix has gained importance. This technique achieves better results on ultimate mechanical, thermal and barrier properties. Recent advances in polymer/clay nanocomposites have inspired large efforts to get better nanofiller dispersion. That is the case of montmorillonite into hydrocarbon polymers like HDPE, PP, etc. To reach good clay dispersion the challenge is to develop an adequate polymer/montmorillonite mixing enthalpy. Usually an ionic exchange with alkyl ammonium ions is carried out to obtain miscible clay with non-polar polymers. Alkyl chains of ammonium ions have the same nature of non-polar polymers. However, these types of ions do not generate necessarily an enthalpic change enough to reach an efficient clay delamination into polymer. For this reason, other type of molecules must be incorporated to the organophilic clay. These molecules must provide useful surface physical modification of montmorillonite, changing the clay- polymer interaction. Fig. 1: X- Ray diffractograms. In order to solve this problem, this work presents a study of silanes as modifiers; a comparison of the effect of different functional groups on organophilic montmorillonite was carried out. An argentinean sodium montmorillonite was treated with hexadecyltrimethyl ammonium (H) to obtain organophilic clay (HMMT). Finally HMMT was treated with (CH3)2SiCl2, (CH3)(C6H5)SiCl2 and (C6H5)2SiCl2 and water. The following clays were obtained: HMMT-PDMS, HMMT-PMPhS, HMMT-PDPhS.