Influence of the RF plasma polymerization process on the barrier properties of coil-coating

By Serra, R.; Zheludkevich, M.L. & Ferreira, M.G.S.
Published in Progress in Organic Coatings NULL 2005

Abstract

The work is devoted to the investigation of the influence of silica-based plasma polymer films deposition on the protective properties of polyurethane coil-coating. Different locations and different deposition stages were investigated for radio frequency (rf) plasma deposition reactor to establish relations between deposition stages and coating properties. The surface evolution of the plasma treated samples was assessed by atomic force microscopy (AFM). Energy dispersive spectroscopy (EDS) was used to study the coating composition and electrochemical impedance spectroscopy (EIS) was used to evaluate the barrier properties and water uptake rate of the different samples. Transmission electron microscopy (TEM) was used to obtain information regarding the polymer structure. The results show that plasma deposition of thin silica-based layer leads to degradation of the barrier properties of the coil-coating. The degree of the coating degradation strongly depends on the electrode location during plasma polymer deposition. The coil-coatings with plasma films deposited on the ground electrode demonstrated higher corrosion protection than the ones prepared on the powered electrode. The oxygen plasma activation of the coil-coatings before silica deposition leads to delamination of the top layer from the surface of the coil-coating during immersion in aqueous solutions. However, oxygen plasma post-treatment of the silica-based top layer tends to improve the barrier properties of the final system.

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