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Preparation, structure, thermal and dielectric properties of polyamide-montmorillonite nanocomposites

Nilufer K�?�?�?�?�?�?�?½v�?�?�?�?�?�?�?½lc�?�?�?�?�?�?�?½m, Turgay Se�?�?�?�?�?�?�?§kin

Polyamide-montmorillonite nanocompositeswere prepared fromsolution of polyamide and the organo modified-montmorillonite (OM-MMT) using Nmethyl- 2-pyrrolidone as a solvent. The reactive organoclay was formed by using hexadecylpyridinium chloride (HPC) as a swelling agent for silicate layers ofmontmorillonite. The swelling process was carried out through ion exchange reaction between the end group of hexadecylpyridinium chloride salt and the sodiumion inmontmorillonite. This irreversible swellingmonitored bymeasuring the cation exchange capacity (CEC) of the montmorillonite solutions. Dispersion of the modified clay in the polyamide (kevlar) matrix resulted in nanostructured material containing intercalated polymer between the silicate layers. The Polyamide-montmorillonite nanocomposites films (PA-MMT) characterized by FTIR, SEM and x-ray were exfoliated nanocomposites at low MMT content (<1 wt.%) and partially exfoliated nanocomposites at high MMT content (containing aggregates of MMT). The clay content significantly influences thermal behavior of the nanocomposite films, such as glass transition and decomposition temperatures of polyamide-montmorillonite nanocomposites. The glass transition temperatures of the nanocomposites were higher than that of the original polyamide. The dielectric properties of the PA–clay nanocomposites were studied in detail. The results displayed that the dielectric constants decreased with the increase of the clay content and the films showed relatively low dielectric constant when the clay content was over 1 wt% compared to pure polyamide.