Influences of low-temperature ambient pressure N2 plasma and flame treatments on polypropylene surfaces

Using various techniques, such as Sum-Frequency Generation (SFG) vibrational spectroscopy, Attenuated Total Reflection Infrared Spectroscopy (ATR-IR), Raman scattering, and Scanning Transmission Electron Microscopy (STEM), this study investigated the influences of N2 plasma and flame treatments on polypropylene surfaces. The results of the first two techniques suggest that the functional groups introduced by the treatments had not been exposed to the air side of the outermost surfaces of the polypropylenes but had been distributed from the surfaces to the bulk regions. Regarding the surface morphology after each treatment, Raman scattering and STEM measurements revealed that the treatments had induced the formation of amorphous regions on the surfaces. On the other hand, the number of functional groups introduced by N2 plasma irradiation was more than that introduced by burning flame. Unlike the flame treatment, the N2 plasma treatment created roughness on the polypropylene surfaces.