Model of non-stationary non-isothermal diffusion of corrosion inhibitors in polymeric film

Abstract

Efficiency of film compositions with a complex of inhibitors at protection of equipment against corrosion is shown. The leading role of diffusion in formation of a protective layer on a substrate is revealed. Relevance of development of model of diffusion of inhibitors of corrosion to a substrate at the expense of the most hostile environment is proved. The specified model will provide calculation of concentration of inhibitor for various types of hostile environment (alkaline, acid) and establishment of necessary thermodynamic characteristics of a polymeric basis. The film on the basis of latex DMMA containing contact and flying water-soluble inhibitors of corrosion was investigated. Methyl Methacrylate latex belongs to the hydrophilic polymers differing in abnormal diffusion. Speed of diffusion of vapors of water through latex films up to 3 mm thick is experimentally established. Assumptions are entered and the mathematical model of an element of a polymeric film added with entry and boundary conditions according to service conditions is developed. Experimental values of the functions describing diffusion of water and inhibitor approximated the bicubic interpolation polynomial realized by standard algorithm of MatLab library. The decision is carried out in a CFD package of modeling Comsol Multiphysics, at the same time the computing grid contained 2128 elements. It is defined that diffusion is complicated by the conformational transformations of macromolecules of a polymeric matrix directly depending on temperature. Change of coefficient of diffusion of a film at endurance in water owing to change of a conformational condition of macromolecules of a film from temperature is experimentally established. It is established that the current of the first minutes is established a gradient of temperatures which results in stationary value of medium-volume temperature of a film. Water diffusion as inertial process establishes a gradient of concentration with orientation of lines of current towards a zone of defect of a film on a substrate. The gradient of concentration of inhibitor grows more slowly, than concentration of water that is caused by initiation of formation of the "inhibitor + water" complex. In process of inhibitor exhaustion directly in a defect zone, its diffusion from the nearby intact areas is excited that raises a functional stock of an anticorrosive covering. Results of comparison of the data on quantitative structure of a polymeric film received experimentally and calculation for model are given, their convergence is shown.