Oberflächenstrukturierung polymerer Fasern durch UV-Laserbestrahlung, 15. Beschreibung des Temperaturfeldes in PETP-Polymeren während und nach der Laserbestrahlung mit einem gepulsten UV-Laser

Abstract

For understanding the generation of UV laser induced surface structures of PETP polymers the temperature field within the irradiated surface is calculated in dependence on the laser irradiation wavelength (193 nm, 248 nm, 308 nm), pulse time, pulse form, the irradiation intensity and depth, using temperature-independent material data of PETP polymers known from literature. For this purpose the solution function of the one-dimensional heat differential equation is used. Depending on the order of magnitude of the absorption coefficient of the polymer for UV light of different wavelengths, surface temperatures of approx. 16 000°C (193 nm), 11 000°C (248 nm) and 500°C (308 nm) are calculated at the end of the laser pulse. The temperature input within the polymer layer is limited to only a very small penetration depth. For the irradiation with the two laser wavelengths of 193 nm and 248 nm this is less then 0.4 μm. The cooling process is considerably slower, reaching the initial temperature after approx. 4 μs.