Structural origin of surface morphological modifications developed on poly(ethylene terephthalate) by excimer laser photoablation

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.