Corona treatment applied to synthetic polymeric monofilaments (PP, PET, and PA-6)

Surface treatment of monofilaments of polypropylene (PP), poly (ethylene terephthalate) (PET), and polyamide-6 (PA-6) was carried out by corona discharge. The process was conducted with an inter-electrode distance of 4 mm and treatment time in the range of 10 s to 120 s using a wire-plan system under controlled ambient conditions. The samples, before and after corona, were characterized through contact angle measurements, water absorption, Fourier transform infrared spectroscopy/attenuated total reflectance (FT-IR/ATR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). After corona, the PP, PET, and PA-6 samples showed water absorption degrees of 9.4%, 8.5%, and 9.1%, respectively. Meanwhile, their dynamic contact angles reduced by 29.6% (PP), 27.9% (PET), and 18.6% (PA-6), while their corresponding surface energies were 71.1 mJ/m², 77.4 mJ/m², and 75 mJ/m², respectively. The FT-IR/ATR, SEM, and DSC results showed that corona treatment effectively improves the wettability of polymeric surfaces through oxidation and surface morphology alteration, but does not affect the bulk thermal properties.