Polyethylene laser welding based on optical absorption variations

Polymeric materials, both pure and containing nanostructures, can be prepared as thin sheets in order to produce joints with an interface between an optically transparent sheet and an optically absorbent substrate to be welded by infrared pulsed laser irradiation. The Laser TransmissionWelding(LTW)techniquehasbeensuccessfullyappliedinordertojointwoormore thermoplasticpolymericsheetsthatmusthaveasimilarchemicalcomposition. Inthisresearchwork, polymeric joints of Ultra High Molecular Weight Polyethylene sheets were realized, characterized and welded. Some polymer sheets were doped, at different concentrations, with carbon nanoparticles absorbent the laser radiation. A pulsed laser operating in the wavelength region 532nm with intensity of the order of 109Watt/cm2 was employed to be transmitted by the transparent polymerandtobeabsorbedbythecarbonenrichedsurface. Attheinterfaceofthetwopolymersthe releasedenergyinducesmelting,thatisassistedbypressure,producingafastandresistantwelding zone. Mechanicalandopticalcharacterizationsandsurfaceanalysesarepresentedanddiscussed.