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Effects of Modifier Concentration on Structure and Viscoelastic Properties of Copolyester/Clay Nanocomposites

Abstract Poly(ethylene glycol‐co‐cyclohexane‐1,4‐dimethanol terephthalate)(PETG)/clay nanocomposites were prepared via melt intercalation technique. The effects of concentration of the organic modifier in the clay on the properties of the nanocomposites were studied. Three clays modified using the same alkyl ammonium modifier, but differing in modifier concentration, are used for this purpose. The nanocomposites are characterized using wide‐angle x‐ray diffraction for their structure. Dynamic mechanical analysis of these nanocomposites is also studied to investigate their viscoelastic behaviors. The x‐ray diffraction study shows an increase in the interlayer spacing of organically modified clays as compared to that of Na+ clay. The extent of increase in the interlayer spacing is dependent on the concentration of organic modifier used to modify the montmorillonite. The presence of well‐defined diffraction peaks and the observed increase in the interlayer spacing in the nanocomposites imply the formation of an intercalated hybrid. Dynamic mechanical properties show an increase in the storage modulus of the nanocomposite over the entire temperature range studied, as compared to the pristine polymer. Investigation of the rubbery plateau modulus confirms the reinforcing effect of organically modified clay. The observed enhancement in the modulus was greater for the clay with the lowest content of the organic modifier. These results indicate that in nanocomposites, apart from the compatibility of the organic modifier with the polymer, its concentration in the interlayer also plays a critical role in the structure development and thus in the enhancement of the properties. The nanocomposites showed reduced damping, which was governed by the modifier concentration in the clay.