In situ polymerization of ε-caprolactam in the presence of polyester polyol and nanosilica toward amorphous polyamide6/SiO₂ nanocomposite

Abstract

Amorphous polyamide6/fumed silica nanocomposites are a new class of polyamides with improved barrier properties. Recently, polymer/fumed silica nanocomposites have received much attention due to the benefits of strongly improved physical, mechanical and chemical properties compared to the pure polymer. In this study, an amorphous nanocomposite of polyamide6 was prepared via in situ polymerization of ε-caprolactam as a monomer, sodium caprolactam as a catalyst, polyester polyol as a comonomer, toluene diisocyanate as an activator and fumed silica as nanoparticles. Effects of different concentrations of polyester polyol and fumed silica on the formation of nanocomposites and their crystallization, gas permeability and dynamic mechanical properties were investigated in comparison with those of the pure nylon6. Physical and mechanical properties of different formulations which prepared via reactive melt blending were determined using dynamic mechanical thermal analysis, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and atomic force microscopy techniques. Barrier properties against oxygen and water absorption were examined, as well. Results showed that addition of 4.96 wt% catalyst, 7 wt% activator, 1 wt% polyester polyol and 3 wt% fumed silica led to the best permeability properties.