In this work, an experimental investigation of fluorine gas (F(2)) plasma treatment of polypropylene (PP) film reveals the evolution of PP fluorination. Surface analysis of fluorinated PP surfaces describes a surface modification process that is initially quite rapid but slows sharply as the fluorination progresses. The fluorination reaction occurs more rapidly at the PP film surface and evidence of a treatment gradient is seen in the ESCA sampling depth of 10 nm. The increasingly fluorinated surface becomes less reactive to the plasma chemistry and develops a fully fluorinated, cross-linked surface layer that eventually extends the full ESCA sampling depth.

Atomic force microscopy (AFM), contact-angle measurements, and X-ray photoelectron spectroscopy (XPS or ESCA) were used to characterize biaxially oriented poly(propylene) (PP) films modified by exposure to a corona discharge. Surface analysis was performed on PP filmsmodified at various corona energies to explore the changes in surface topography, wettability, and oxidation state resulting from the corona treatment. Even at low corona energies, water-soluble low-molecular-weight oxidized materials (LMWOM) are formed. These LMWOM products agglomerate into small topographical mounds that are visible in the AFM images. For the detection of LMWOM on corona-treated surfaces, AFM appears to be at least as sensitive as contact-angle measurements or ESCA. A major advantages of AFM relative to the other surface analytical techniques used to confirm the presence of the LMWOM is that no washing of the surface with water is required in conjunction with the AFM analysis.

The flame treatment of polypropylene (PP) film involves the use of impinging, conical flames to oxidize the surface of the PP. Depending on treatment conditions, the PP film can be exposed to an inhomogeneous environment because of the conical shape of the flames. This environment can lead to cross-web variations, or 'lanes', in the wettability of the film. We have developed a simple method to quantify these non-uniformities using the information provided by the Wilhelmy plate technique of dynamic contact angle measurement. Both surface-averaged and spatially resolved surface-energy data can be obtained by this technique. In the case of our PP film, the spatial non-uniformities were found to be caused by variations in surface chemistry, not topography. These nonuniformities are not observed on untreated PP. Use of this method enables a quantitative evaluation of the effects of flame-treatment process variables on treatment uniformity.