Simulation of chemical modification of polymer surface

•The mathematical model describing chemical interaction of a polymer film with a reagent gas is developed.•The model allows for changes in the chemical composition, structure, and physicochemical properties of the polymer as a result of modification.•The results of calculations of fluorination degrees conducted within the framework of the model agree with the experimental data.•The effects of surface layer transformed via fluorination on certain important characteristics of films are revealed.•These effects include increase in the chemical resistance of pipes, reduction in fuel penetration of fuel tanks, etc. The mathematical model describing chemical interaction of a polymer film with a reagent gas is developed. This model allows for significant changes in the chemical composition, structure, and physicochemical properties of the polymer as a result of modification. For certain types of surface modification, such as fluorination, a number of limitations and assumptions may be drawn that make it possible to perform the analytical solution of equations which are used as a basis to calculate the depths and profiles of equal fluorination degrees for various amorphous–crystalline polymers. The results of calculations of fluorination degrees conducted within the framework of the model are in fairly good agreement with the experimental data. The effects of surface layer transformed via fluorination on certain important characteristics of films and articles manufactured from polyethylene of various brands are revealed. These effects include increase in the chemical resistance of pipes, decrease in their permeability for low-molecular-mass compounds, reduction in fuel penetration of fuel tanks, and improvement in the thermal compatibility of films.