Factors for the aging effects on the surface characteristics of the plasma treated polyethylene

Some factors for aging time effects on the wettability and polar group ratio of the nitrogen glow-discharged (G.D.) low density polyethylene (N-2-LDPE) and plasma-polymerized (N-2-P-C2H4) films were studied with measurement of the contact angles, X-ray photoelectron spectra (XPS), and shear strength. In the case of the N-2-LDPE film, the decomposed low molecular weigth polar substances were dispersed into air (immediately after G.D.), and the grafted polar groups at the film surface were reversed into inert regions of the film (for about 20 days after G.D.). In the case of the N-2-P-C2H4, the main factor was dispersion of the polar low molecular weight substances from the film. The shear strength of the N-2-LDPE film immediately after G.D. was weak, because the film was covered with the low molecular weight substances. The shear strength of the film treated with heat was strong, because the low molecular weight substances were dispersed from the film.