Synergistic effects of biobased PLA and Garnet waste towards enhanced corrosion resistance of epoxy coating

Artikel i vetenskaplig tidskrift, 2025

In this study, an eco-friendly hybrid epoxy coating was formulated by incorporating bio-based polylactic acid (PLA) and garnet waste into an epoxy matrix to enhance corrosion resistance on mild steel in 3.5 % NaCl. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) demonstrated that the Epoxy/PLA/Garnet (15 %) coating exhibited superior protection, with the lowest corrosion rate of 2.15 × 10⁻⁷ mm/year and a significant increase in charge transfer resistance. FTIR analysis confirmed the successful chemical interaction between epoxy, PLA, and garnet, indicated by shifted and intensified characteristic absorption bands, particularly in the C = O and Si–O–Si stretching regions. XRD patterns revealed decreased crystallinity and peak broadening, signifying uniform filler dispersion. Atomic force microscopy showed a smoother and denser surface morphology for the 15 % garnet coating, with reduced surface roughness compared to neat epoxy. SEM further validated uniform coating coverage and fewer micro-defects. The combined results affirm that garnet acts as a barrier-enhancing filler, while PLA contributes to hydrophobicity and eco-compatibility. This synergistic combination offers a promising green route for corrosion-resistant coatings in marine and industrial environments.