Surface modification of vulcanized EPDM rubber by Ag (II): Kinetic study of Ag (II) generation and surface characterization

Abstract

Ethylene propylene diene monomer (EPDM) rubber has been widely used in the various outdoor and industrial applications. However, in order to improve its adhesion properties it needs some surface modification. Mediated electrochemical oxidation by Ag (II) was thus employed to evaluate the feasibility of EPDM surface modification. The electrochemical behavior of Ag (I) /Ag (II) redox couple was initially studied at different temperatures in an electro-membrane cell using IrO2/Ta2O5anode. The reversibility of the redox reaction improved at low temperatures. The apparent rate constant for Ag (I) oxidation (k1) at 3 kA m-2 was (s-1). The surface chemistry, morphology and wettability of the activated EPDM rubber by Ag (II) were then analyzed and the modified EPDM surface showed a significant decrease in the water contact angle resulting in an increase in the surface free energy and improved wettability. ATR analysis revealed presence of oxygen-containing polar groups on the modified rubber surface. SEM results showed that the short treatment time at room temperature only changed the morphology of the rubber surface, which is attributed to the etching of the outermost surface.