SURFACE MODIFICATION OF POLYMER FIBERS BY UV LASER IRRADIATION .12. PHENOMENOLOGICAL INVESTIGATIONS ON THE DEPENDENCE OF UV LASER-INDUCED SURFACE MODIFICATION OF POLY(ETHYLENETEREPHTHALATE)FIBERS ON THE PULSE NUMBER

By the pulsed irradiation of drawn PETP-fibers with a pulsed UV-excimer-laser, the well-known, roll-like, submicron morphology is generated on the polymer surface. An experiment, where PETP-fibers were irradiated in place in a microscope, allowed to observe the evolution of the structure shot by shot. This was investigated for various laser fluences and wavelengths and in dependence of the draw ratio of the fibers. With increasing number of shots, the morphology gets more coarse due to a kind of 'growing together' of the rolls. Characteristically, the fiber decomposes in ellipsoidal fragments after a sufficient number of shots. Quantitative evaluation gave a logarithmic dependence of roll-distance on shot number.