Development of active barrier effect of hybrid chitosan/silica composite epoxy-based coating on mild steel surface
By Wonnie Ma, I.A.; Sh., Ammar; Bashir, Shahid; A Kumar, Sachin S.; K, Ramesh; S, Ramesh
Published in Surfaces and Interfaces
2021
Abstract
In this study, a co-action behavior of a hybrid composed of chitosan and silica was investigated by incorporating it into an epoxy resin to induce an active barrier effect on the metal surface. The chemical structure and porosity of the hybrid chitosan and silica were determined using Fourier-Transform Nuclear Magnetic Resonance (FT-NMR) and Brunauer–Emmett–Teller (BET), respectively. The dispersion of the hybrid chitosan/silica incorporated within the epoxy matrix was observed via Environmental Scanning Electron Microscopy (ESEM) and Fourier Transform Infrared Spectroscopy (FTIR). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were exploited to examine the thermal stability. The wettability and degree of transparency of the hybrid composite coatings were found to be increased after being exposed to the corrosive medium and also were investigated using the contact angle (CA) measurement and ultraviolet-visible (UV–Vis) spectroscopy, respectively. CS0.8 coating has shown an increase in contact angle from 82.4 at normal condition and 89.4 and 83.6 to the exposure to NaCl solution and UV exposure respectively. The active barrier effect of the developed hybrid composite coating on mild steel surface was evaluated by the electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution to which 0.8 wt.% of hybrid chitosan/silica mass fraction exhibited pronounced impedance value up to 1010 Ω cm2 and the breakpoint frequency performed a full capacitive region even after the 60th day of exposure to the accelerated corrosive ions penetration test.