Anticorrosive performance of epoxy/modified clay nanocomposites

Abstract

The effect of 2‐benzylbenzimidazole (2‐BBI) was evaluated as surface modifier on the performance of Na+‐Montmorillonite nanoparticles (Na+‐MMT) in epoxy‐based coatings. Four epoxy‐based samples were prepared including 0, 1, 2, and 3 wt% of 2‐BBI‐(Na+‐MMT). The intercalation behaviors of epoxy resin in presence of 2‐BBI‐(Na+‐MMT) were determined by X‐ray diffraction (XRD), and field emission scanning electron microscope (FE‐SEM) analysis was carried out to depict the dispersion of 2‐BBI‐(Na+‐MMT). The pertaining reaction bonds of the 2‐BBI and (Na+‐MMT) were represented via Fourier transform infrared spectroscopy (FTIR), and pull‐off test was used for measuring the adhesion strength of the coated samples. Corrosion resistance and thermal properties of the coated samples were measured by electrochemical impedance spectroscopy (EIS) and differential scanning calorimetry (DSC), respectively. On the basis of the EIS results, the coated samples with 3 wt% 2‐BBI‐(Na+‐MMT)/epoxy had the highest corrosion resistance after 120 days immersion in 3.5 wt% NaCl solution. Also, based on the Brusher–Kingsbury equation, the amount of water absorption was calculated, in which 3 wt% 2‐BBI‐(Na+‐MMT)/epoxy had only 1.92% water absorption while 3 wt% (Na+‐MMT)/epoxy had 82 wt%. The results showed that 2‐BBI can improve the dispersion of the Na+‐MMT in the epoxy matrix by entering into their galleries and providing better compatibility between the inorganic clay nanoparticles and polymeric matrix. This issue led to the enhancement of the thermal and barrier properties of 2‐BBI‐modified (Na+‐MMT)/epoxy nanocomposites rather than unmodified ones. POLYM. COMPOS., 39:E2134–E2142, 2018. © 2017 Society of Plastics Engineers