Concentration dependences of the coefficients of acid diffusion into epoxy binders of anticorrosion coatings

• V.A. Golovin and A.B. Il’in

A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky pr. 31, 119071 Moscow, Russian Federation

Abstract: Experimental data on diffusion profiles of various acids in polymer materials based on epoxy resins and mathematical methods for calculating the concentration dependences of diffusion coefficients are considered. It has been shown that all the acids studied are characterized by the same type of concentration distribution profiles for the diffusion of both anhydrous and aqueous solutions of inorganic and organic acids. The profiles have a stepped shape with a sharp jump at the so-called penetration boundary and a smooth transition in the penetration zone between the outer boundary of the sample and the sharp internal concentration boundary (penetration boundary). Mathematical processing of the diffusion profile using the Boltzmann-Matano method with preliminary smoothing with a B-spline yielded the dependence of the acid diffusion coefficient on the acid concentration and/or diffusion coordinate. The concentration dependences of D_v, like the profiles, have a qualitatively identical S-like shape. The D_v value increases with an increase in acid concentration but the diffusion coefficients vary significantly in the ratio of D_v (min) and D_v (max).

Keywords: acid diffusion, diffusion profile, Boltzmann–Matano method, diffusion coefficient, concentration dependence, multilayer polymer anti-corrosion coatings

Int. J. Corros. Scale Inhib., 2023, 12, no. 4, 1979-1991
doi: 10.17675/2305-6894-2023-12-4-29

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