Pulsed laser treatments of polyethylene films

A Nd:Yag pulsed laser, 3 ns pulse width, 150 mJ pulse energy, operating at the second harmonics (532 nm) has been used to irradiate in air polyethylene thin films. The thermal and chemical effects induced by the laser irradiation in the polymer are responsible of the hydrogen and CxHy groups emission at long irradiation times. A special study, concerning the welding effect between two different types of polyethylene films, one transparent and the other strong absorbent the laser light, was performed. The welding, at the interface of the two pressed polymers, depends on the optical and micro-structural material properties besides the irradiation time. In particular, polymers with different viscosity, melting temperature and crystalline degree exhibit different mechanical behaviour. Different techniques were employed to investigate on the polymeric welding effects, such as the mass quadrupole spectrometry, the scanning electron microscope, the surface profiler and the mechanical strength measurement.