Ar/O
2
plasma modified vulcanized EPDM rubber co-cured with
natural rubber. A set of identified process variables such as rf
power, treatment time and composition of the gas mixture have
been chosen and their effect on adhesion has been thoroughly
investigated. The degree of surface modification is dependent on
the plasma composition and operating parameters including rf
power and treatment time. The measured surface energy shows
a significant improvement with the plasma treatment. The substantial
enhancement of surface energy is in agreement with
the polarity, due to presence of oxygen containing groups, confirmed
by the ATR-IR and the XPS analysis. During the plasma
treatment, the rubber surface is bombarded by ions, electrons
and UV irradiation causing surface rougher as compared to
the untreated rubber. Although the rubber surface is effectively
modified by the plasma treatment, the peel strength attains a
maximum at a certain level. The decrement of peel strength
after longer plasma treatment may be explained on the basis
of meager improvement of surface energy, and anti-adherent
nature of blooming sulfur (proven from EDX, ATR-IR, XPS and
free sulfur estimation from chemical analysis). A maximum of 98%
improvement has been observed for the plasma treated sample
designated as EP
in comparison to its unmodified counterpart.
100W/10/90Ar