Abstract
An account of the experiments on preparing polystyrene (PS) nanocomposites through grafting the polymer onto organophilic montmorillonite is reported. Cloisite 20A was reacted with vinyltrichlorosilane to replace the edge hydroxyl groups of the clay with a vinyl moiety. Because the reaction may liberate HCl, it was performed in the presence of sodium hydrogencarbonate to prevent the exchange of quaternary alkylammonium cations with H+ ions. Only the silanol groups on the edge of the clay react with vinyltrichlorosilane. The radical polymerization of the product with styrene as a vinyl monomer leads to chemical grafting of PS onto the montmorillonite surface. The homopolymer formed during polymerization was separated from the grafted organoclay by Soxhlet extraction. Chemical grafting of the polymer onto Cloisite 20A was confirmed by infrared spectroscopy. The prepared nanocomposite materials and the grafted nano-particles were studied by XRD. Exfoliated nanocomposites may be obtained for 0.5 wt%–1 wt% clay content. The nanocomposites were studied by thermogravimertic analysis (TGA) dynamic thermal analysis (DTA) and dynamic mechanical analysis (DMTA).
Highlights
The field of polymer nanocomposites has attracted considerable attention recently
Chemical grafting of the polymer onto the Cloisite 20A surface was confirmed by FTIR spectroscopy
Polymer-clay nanocomposites with different clay contents were prepared by free radical copolymerization of vinyl-silylated Cloisite 20A and styrene monomer in toluene
Summary
The field of polymer nanocomposites has attracted considerable attention recently. Much attention has been paid to polymer/montmorillonite (MMT) nanocomposites, because its lamellar elements display high in-plane strength, stiffness, high aspect ratio, high thermal stability and better barrier properties even with small amount of silicate[1−4]. Natural clays are generally hydrophilic and it is necessary that they are modified so that miscibility between the clay and the polymer is enhanced. A cation exchange process achieves the organic modification of the clay. The inorganic cation, usually sodium, is replaced by an organic cation, typically ammonium and phosphonium[5]. PS is an inexpensive, hard thermoplastic and one of the most widely used commercial polymers because of its favorable mechanical, electric insulation, thermal insulation and good solvent resistance properties
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