Effects of curing temperature and addition of functionalized graphene oxide on corrosion barrier performance of phenol furfural polymer-amino phenolic resin composite

Abstract

Phenol furfural polymer (PFP) blended amino phenolic resin (APR) and functionalized graphene oxide (FGO) dispersed PFP/APR polymer composite coatings were fabricated and evaluated their barrier performance on mild steel (MS) corrosion at different curing temperatures without using any conventional hardeners. The PFP was synthesized by condensation polymerization and blended with the prepared APR to get PFP/APR polymer composite. The GO was functionalized with 4-(trifluoromethyl) benzohydrazide (TFB) and dissipated in PFP/APR composite matrix. The synthesized materials were characterized by FT-IR, Raman, XRD, XPS, EDS, SEM and TEM techniques. The thermal stability of GO and FGO was analyzed using TGA. The fabricated composite materials were coated on MS surface and their surface morphology, anti-corrosion potential and hydrophobic character were evaluated by SEM, optical images, electrochemical impedance spectroscopy (EIS), salt spray analysis (SSA) and contact angle measurements (CA). At 70 °C curing temperature, the PFP/APR coating showed maximum coating resistance (Rc) of 1.39 × 105 Ω cm2 and charge transfer resistance (Rct) of 2.63 × 105 Ω cm2 on 60th day of immersion in 3.5 wt% NaCl solution. Addition of 0.2 wt% FGO into PFP/APR matrix reduced the ideal curing temperature to 50 °C and exhibited an admirable barrier performance even after 90 days of immersion in saline medium with a reliable Rc and Rct values of 1.24 × 105 Ω cm2, 1.93 × 105 Ω cm2 respectively, and coating capacitance (Qc) in the range of 10−9 F/cm2. The cross linking of resin and blockade of defects by nanofiller make the material highly durable and superior in extensive corrosive environment.