The Relationship of Surface Energy Parameters and Adhesion Characteristics of Modified Ethylene Copolymer–Metal Compounds

Abstract

Polymer composite materials based on ethylene–vinyl-acetate copolymer modified with various petroleum polymer resins applied to steel substrates were investigated. In the process of measuring the surface-energy characteristics by wetting with test liquids and calculating them using the Owens–Wendt and Van Oss–Chaudhury–Good equations, it was found that modification with resins increases the acidic (according to Lewis) properties of compositions—the free surface energy’s acid–base component and the acid parameter. The cathodic disbondment method was used to estimate the adhesive strength of modified coatings on steel, which agrees with the defect diameter in the coating after an 8-h experiment. Experimental results obtained in this work are confirmed by theoretical calculations, as a result of which the dependences were found between the defect diameter after cathodic disbondment and such surface-energy characteristics as the acid–base component of the free surface energy of polymer composites, the reduced acidity parameter, and the thermodynamic work of adhesion. Dependences obtained have a decreasing exponential nature. Based on the conducted research, a conclusion was made about the correspondence of the adhesive strength of modified polymer coatings on steel assessed under cathodic polarization conditions, as well as the thermodynamic characteristics of the materials being joined.