Rapid surface modification of EPDM with oxygen and nitrogen plasmas: A comparative study

Abstract

This work presents the adhesion properties of plasma treated EPDM (ethylene propylene diene monomer) vulcanized rubber used in missile and rocket manufacturing. The EPDM rubber surface was treated in a RIE (reactive ion etching) plasma reactor using two different gas mixtures, oxygen/argon and nitrogen/argon. Contact angle measurements were used to obtain the dispersive and polar components of the surface tension of the treated samples, and FT-IR was used to characterize the surface. Both plasma treatments promote an enhancement of the adhesive properties of the EPDM rubber. However, the improvement factor depends on the gas mixture used. For treatment with an oxygen/argon mixture, functional groups such as C-O, C=O, O-C=O, C-O-O and CO3 are formed in the rubber surface. In the case of a nitrogen/argon mixture, the functional groups formed on the surface are C-N, C=N and C=N, beyond the functional groups C-O, due to the rubber oxidation. Therefore, the higher polarity of nitrogen containing groups makes the treatment with the nitrogen/argon mixture more efficient.

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