  The in-depth oxygen diffusion into a low density polyethylene film is
performed in the post-discharge of an atmospheric plasma torch, supplied in
argon as carrier gas and with or without oxygen as reactive gas. The chemical
and structural properties of the polymer surface and bulk are studied in terms
of plasma parameters (treatment time, power, and reactive gas flow rate). A
good correlation between XPS and Fourier transform infrared spectroscopy
analyses is demonstrated. The penetration depth of oxygen into the bulk of the
polymer is investigated by angle resolved-XPS and time-of-flight SIMS. It is
shown that, depending on the plasma conditions, oxygen could penetrate up to
20--40 nm into the low density polyethylene during the atmospheric plasma
treatment.
