Development of cardanol based antibacterial and anticorrosive bio-polyurea-epoxy composite coating for mild steel surface

Corrosion and bacterial resistance in the field of high-performance epoxy composite coatings are tough to accomplish simultaneously. The present work seeks to investigate the viability of utilizing a bio-polyurea epoxy (BPUE) resin derived from renewable resources i.e., cardanol with good physico-mechanical, anticorrosive, and antibacterial properties. Initially, bio-polyurea (BP) was developed using cardanol followed by its chemical tethering {(20 %, 30 %, 40 %, and 50 %) with commercially available epoxy (Diglycidyl ether of bisphenol-A (DGEBA)}. After the synthesis of BPUE thermosets, an analysis of their chemical structure was conducted by Fourier transform infrared (FTIR) and Nuclear magnetic resonance (NMR) spectroscopy. The evaluation of the BPUE composite coatings encompassed a comprehensive characterization through employing established ASTM standards. It revealed that out of all the synthesized compositions BPUE₃ exhibited excellent thermal stability (5–10 % wt. loss at 327 °C to 357 °C), mechanically resistant (Impact resistance: 150 lb./in., Pencil hardness: 5H, Scratch hardness: 2.5 kg, Crosshatch: 100 %, bending: 1/8 in., Wear resistance: 4.6 mg wt. loss per 1800 cycles, and Gloss value: 108 G.U.) and hydrophobic properties (water contact angle over 100^o). Overall, the BPUE thermoset composite coatings from agro-by-product materials have excellent potential for combatting corrosion and bacterial activities.