Electrochemical Behavior and Ionic Permeability of Polyurethane Coatings: A Comparative Study of HDI and IPDI-Based Systems

This study evaluates HDI- (NS) and IPDI-based (ZS) polyurethane coatings using an industrial acrylic polyol (Settalux ۱۱۵۲). Permeability tests reveal ZS's superior barrier properties, showing ۰.۸۲% Na+ permeation at ۳۵ days versus ۱.۶۵% for NS. Electrochemical analysis demonstrates ZS's enhanced stability: OCP maintains -۱۰۰ mV after ۷۰ days (NS fails at -۶۳۰ mV by day ۲۱) and EIS shows higher impedance (۱۰۸ vs ۱۰۶ Q۲ cm²). The IPDI-based coating's performance stems from its cycloaliphatic structure, which simultaneously enhances crosslink density, reduces ionic pathways, and maintains electrochemical stability. These findings demonstrate that isocyanate selection critically determines polyurethane coating performance and IPDI-based coating provides better corrosion protection compared to the HDI-based system in aggressive environments.

کلیدواژه ها:

Polyurethane coating ، HDI ، IPDI ، Corrosion ، Electrochemical Impedance Spectroscopy