Morphological modification of poly (ethylene terephthalate) surface after excimer laser irradiation

摘要

Poly (ethylene terephthalate) was modified by a KrF excimer laser 248nm. It was observed that the PET surface developed a very often periodic roughness or ripple. The roughness size is in the micron range and the surface shows some sign of global melting. Irradiated samples were imaged and studied using atomic force microscopy (AFM) and scanning electronic microscopy (SEM). AFM was used to follow the morphological changes caused by subsequent laser pulses on the very same area of the irradiated PET samples. AFM also provided quantitative data on the laser induced surface and allowed three-dimensional imaging of nonconducting surfaces. Changes in surface morphology of PET fibres were found in relation to laser energy applied. The mean roll to roll distance increased with increasing laser energy. Merging of ripples was observed and believed to be a major reason of increased roll to roll distance. With approximately 50 to 200 pulses, ripple almost approached parallelism. No further change of PET surface was observed with more laser pulses applied since the fibre has disintegrated into "ellipsoidal segments". Meander-like structures superimposed onto the top of the ripples were observed. The wetting property of PET due to laser treatment was also studied.