Abstract
Plasma treatments have faced growing interest as important strategy to modify the hydrophobic/hydrophilic characteristics of materials. However, challenges related to the plasma modification of polymers are the improvement of the chemical resistance without decreasing the mechanical resistance. In this letter, we present for the first time a plasma treatment, using Sulfur hexafluoride (SF6), analogous to vulcanization process, of natural rubber surface, which resulted in a chemical and tension resistance improvements. The natural rubber membranes were coated with glow discharge plasmas generated in sulfur hexafluoride (SF6) atmospheres at a total pressure of 160 mTorr and applying 70 W of radiofrequency. Plasma treatment increases the contact angles from 64° to 125° i.e. leading to a hydrophobic surface. The tension at rupture increased from 3.7 to 6.1 MPa compared to natural rubber without plasma treatment demonstrated by stress-strain investigation. These results provide a fast alternative approach to improve mechanical and chemical properties of rubber-based products.
Highlights
In this work, uncoated and coated AA2024-T3 alloys were tested in solutions of NaCl 3.5wt% at room temperature
The results have demonstrated promising and allow to establish strategies for implementation of the electrochemical impedance spectroscopy technique in surface treatment processes
In analysis of variance (ANOVA), P value is the probability value which gives the degree of confidence at which the factor is significant
Summary
In this work, uncoated and coated AA2024-T3 alloys were tested in solutions of NaCl 3.5wt% at room temperature. Some simulations of surface degradation via standardized accelerated tests (salt spray test) and simulations of common defects in process or assembly operations in aircraft manufacture according to valid standards in the aeronautical industry were made on coated AA2024-T3 specimens These surfaces were tested using electrochemical impedance spectroscopy under the same experimental conditions (3.5 wt% NaCl, room temperature, 0.1Hz-100kHz). Due to their high mechanical strength/weight ratio, they are largely used in aerospace and aircraft structural applications These alloys have poor localized corrosion resistance due to copper that tends to precipitate at grain boundaries, turning these copper rich regions more cathodic than the surrounding aluminium matrix that will act as anode or preferencial site for corrosion through galvanic coupling. Among the finish coating (synthetic enamel, lacquers, polyurethane, urethane, acrylic urethane), polyurethane is preferred in aviation industry for abrasion-, stain-, and chemical-resistance and high degree of resistance to damage from UV rays from the sun [7]
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