Abstract :
Pulsed laser ablation of ultra-high-molecular-weight-polyethylene (UHMWPE) is investigated at Prague Asterix Laser
System (PALS) Laboratory. The high ablation yield as a function of laser energy is presented at 438 nm laser wavelength. The
mechanisms of the polymer ablation are studied on the base of ‘‘in situ’’ analysis, such as mass quadrupole spectrometry and
time-of-flight measurements, and ‘‘ex situ’’ analysis, such as SEM investigations and Raman spectroscopy.
Results show that the laser irradiation induces a strong polymer dehydrogenation and molecular emission due to different
CxHy groups having high kinetic energy and high charge state. At a laser pulse energy of 150 J the Hþ, Cnþ ions (n ¼ 1 to 6) are
emitted from the plasma with velocities of the order of 108 cm/s, while the CxHy groups and the carbon clusters, detected up to
C16, have a velocity about one or two order magnitude lower.
The laser ablation process produces a deep crater in the polymer, which depth depends on the laser pulse energy and it is of the
order of 500 mm. The crater volume increases with the laser pulse energy. Results demonstrated that the laser radiation modifies
the polymer chains because dehydrogenated material and carbon-like structures are detected in the crater walls and in the bottom
of the crater, respectively.
A comparison of the experimental results with the data available in literature is presented and discussed.
# 2004 Elsevier B.V. All rights reserved.
