Corrosion Protection Performance of PVDF/PMMA-Blended Coatings by Electrochemical Impedance Method

The effect of mixing ratio on the corrosion protection of carbon steel coated by a film composed of poly(vinylidene) fluoride (PVDF) and poly(methyl methacrylate) (PMMA) was examined using electrochemical impedance spectroscopy. Surface crystallization behavior and thermal properties of the PVDF/PMMA coated carbon steel were evaluated using polarized optical microscopy and differential scanning calorimetry, respectively. A Maltese cross-pattern spherulite crystal was observed in the PVDF/PMMA coating film, which became more apparent with increasing PVDF content. The highest corrosion protection performance was achieved with 60 wt.% PVDF-coated carbon steel, and delamination and corrosion reactions were observed for 20 wt.% PVDF-coated carbon steel. Further, corrosion protection performance with an amorphous/crystal mixture (PVDF/PMMA, 60/40 (w/w)) was better than those observed in the amorphous domain and the perfect-crystal domain of the PVDF/PMMA blended coating system.