The ablation of poly(ethylene terephthalate) (PET) by Ar-F laser radiation has been studied at different fluences for amorphous and semicrystalline samples by scanning electron microscopy (SEM) and by etch-depth measurements. The surface structure created on PET has been interpreted as resulting mainly from a difference in the etch rate—and not the ablation threshold—between amorphous and semicrystalline PET. SEM pictures clearly show the melting of the PET surface at high fluence (≥80 to 100 mJ/cm2) and not below that value. UV laser etching is proposed as a quick and easy method for observing the crystalline subsurface structure of aromatic semicrystalline polymers, as long as low fluence and a low pulse repetition rate are used.
We have investigated by x-ray photoelectron spectroscopy (XPS) the surface of two polymers [polytetrafluoroethylene and polyethyleneterepthalate (PTFE) and (PET)] which were previously submitted to pulsed UV radiation delivered from an excimer laser (ArF: λ=193 nm). Treatments realized under different gaseous atmospheres allow us to point out mechanisms leading to several chemical transformations at the polymer surface. In the case of PTFE, the high-fluence irradiations produce defluorination with surface oxidation. The latter is mainly due to air moisture. The deposition of some ablated fragments on the surface has also been observed. For PET, the major modifications are produced below the ablation threshold. They are characterized by severe deoxidation due to the loss of CO and CO2. The irradiations under oxygen and nitrogen atmospheres show the possibility of grafting new functionalities at the polymer surface.
Several commercial polymers—poly(ethylene) (PE), poly(propylene) (PP), poly(vinylidene fluoride) (PVF2), poly(vinyl chloride) (PVC) and polystyrene (PS)—were treated in air with an argon‐fluorine UV excimer laser (λ = 193 nm).
The polymer etch rate was investigated by two methods: quartz crystal microbalance (QCM) and piercing of films.
X‐ray photoelectron spectroscopy (XPS) analysis was performed on the modified surfaces after laser exposure at various fluences. Samples were subsequently analysed by scanning electron microscopy (SEM).
From our results, polymers may be classified into two categories concerning their reactivity towards UV laser light.
— the weakly absorbing polymers (e.g. PE, PP, PVF2) where a photothermal process (thermal degradation) dominates the interaction.
— the strongly absorbing polymers (e.g. PVC, PS) where a photochemical process (photoablation) dominates the interaction.
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