Novel polyamide 6 nanocomposites with graphene oxide-modified silica

Graphene oxide-modified silica (GO-SiO2) with particle sizes of 30 and 60 nm was obtained by sol-gel method and used as a hybrid nanofiller for polyamide 6. Maleic anhydride (MAH) was used to improve the interactions between the filler and the polymer matrix. The composites were obtained by extrusion. A constant amount of GO-SiO2 (1 wt%) and MAH (0.5 wt%) was used. Photon correlation spectroscopy, SEM and low temperature nitrogen adsorption were used to characterize GO-SiO2. The composites were evaluated by ATR-FT-IR, SEM, DSC, DMTA and TGA. The crystal structure, thermal properties, water absorption and mechanical properties were investigated. The results showed that GOSiO2 acts as a nucleating agent, increasing the crystallinity and crystallization temperature of the com- posites. In addition, GO-SiO2 increased the stiffness of PA, with a greater effect for larger silica particles (60 nm). MAH slightly decreased stiffness and crystallinity but improved the tensile and impact proper- ties because of the homogeneous dispersion of GO-SiO2 in the polymer matrix, as well as improved in- terfacial interactions (SEM). Furthermore, the composites showed lower water absorption (by 30%) and higher thermal stability as evidenced by higher T 10% (1-6 degrees C) and T max (10-20 degrees C).