Low pressure oxygen plasma has been used to improve the surface wettability of a polyurethane film. The modifications induced by the plasma treatment in the material were analyzed using contact angle measurements. X-ray photoelectron spectroscopy technique was used for surface characterization of the plasma-treated films. Atomic force microscopy and scanning electron microscopy were used to analyze topography changes due to the plasma-etching mechanism. The results show a much better surface wettability of the film even for short exposure times, with a considerable increase in the surface energy values. As expected, functionalization with oxygen plasma is mainly because of surface oxidation with species like (CÀ ÀO, C¼ ¼O, OH, etc). An aging process with regard to polar groups rearrangement has been observed, thus promoting a partial hydrophobic recovery. Besides functionalization, the surface wettability of the material improves as a consequence of a slight increase in surface roughness because of the etching effect of oxygen plasma.
Low pressure glow discharge nitrogen plasma has been used to improve wettability in a low density polyethylene (LDPE) film for technical applications. The plasma treatment was carried out at a power of 300 W for different exposure times in the 1-20 min range. Wettability changes were analyzed using contact angle measurements. In addition to this, plasma-treated samples were subjected to an aging process to determine the durability of the plasma treatment. X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy were used for surface characterization. The nitrogen plasma treatment considerably reduced contact angle values thus indicating an increase in surface wettability. The spectroscopic study showed presence of oxygen-based species on the plasma-treated samples, which are mainly generated after the plasma treatment as a consequence of air exposure. These polar species contribute to improve surface functionalization, but this is almost lost during aging due to the hydrophobic recovery process. Microscopic studies revealed that also small changes in surface roughness occurred during the plasma treatment but these are very low compared to surface activation. The results confirmed that low pressure nitrogen can be considered as an environmentally efficient process to improve wettability in low density polyethylene films. V V C 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45:
In this work, surface modification of low density polyethylene (LDPE) film has been carried out to optimize adhesive joints with polyolefin foam for uses in technological applications. LDPE films were modified in a continuous way using corona discharge plasma with different powers, ranging from 200 to 600 W and several film advance rates in the 5-20 m min À1 range. Changes in surface wettability have been studied with contact angle measurements and subsequent solid surface energy calculation. A polyurethane adhesive was used to join the LDPE film to a polyethylene foam. Mechanical performance of the adhesive joints has been determined by T-peel tests and also the aging effects of several hydrothermal conditions have been studied to evaluate the usefulness of these laminate composites in technological applications. Results show that corona discharge powers between 400 and 600 W are suitable in terms of wettability improvement; on other hand, a slight decrease in surface wettability as the film advance rate increases is detected but the overall changes as a consequence of the film advance rate in the 5-20 m min À1 range are small if compared to changes derived from working powers in the 200-600 W range. Adhesive joints offer excellent mechanical performance and good durability in hydrothermal conditions thus being appropriate for technical applications.
A low pressure glow discharge nitrogen plasma has been used to modify wettability of a polyurethane film and, consequently, improve adhesion properties to polyolefin foam in order to obtain technical laminates for uses in automotive industry. A significant increase in surface wettability is achieved after the plasma treatment as observed by contact angle measurements. Surface changes have been studied by X‐ray photoelectron spectroscopy (insertion of polar groups) and atomic force microscopy (changes in surface roughness and topography). Laminates based on plasma‐treated polyurethane film and polyolefin foam show a considerable increase in the T‐peel strength of the adhesion joint; furthermore we can observe a slight ageing process under aggressive conditions (high temperature and relative humidity).
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