Significant slowdown of plasma-optimized surface energy deactivation by vacuum sealing for efficient adhesive bonding. (1st July 2022)

• Record Type: Journal Article
• Authors: Shin, Yongsoon; Qiao, Yao; Canfield, Nathan; Yu, Zeyang; Meyer, Harry M.; Merkel, Daniel R.; Nickerson, Ethan K.; Kanbargi, Nihal S.; Ortiz, Angel; Naskar, Amit K.; Simmons, Kevin L.
• Is Part Of: Composites. Number 240(2022)
• Publication Date: 2022-07-01
• Subjects: Surface treatments -- Surface energy -- Polymer-matrix composites (PMCs) -- Surface analysis -- Joint/joining; Composite materials -- Periodicals; Materials science -- Periodicals; Composite materials; Periodicals; Electronic journals; 620.118
• DOI: 10.1016/j.compositesb.2022.110001
• Languages: English
• ISSNs: 1359-8368

Abstract

Abstract: This work proposes an approach to minimize surface energy deactivation of plasma-treated metal and carbon fiber-reinforced polymer (CFRP) surfaces by vacuum sealing. Plasma treatments enhance adhesive wettability on post-treated surfaces for adhesive joints, but the treated surfaces deactivate quickly in air. The surface energy of aluminum alloy AA6061 and carbon fiber-reinforced polymer-polyamide (CFRP-PA66) optimally treated by a blown air plasma instrument returns to the original surface energy within 1 h. Vacuum sealing of AA6061 and CFRP-PA66 reduced the surface energy deactivation over 7 days by at least 230 times and 970 times compared to in air. Double Cantilever Beam (DCB) tests performed on adhesively-bonded AA6061/CFRP-PA66 joints showed that the total energy release and energy dissipation before failure of plasma-treated and vacuum-sealed materials was up to 60% more than plasma-treated materials without vacuum sealing and up to 125% more than non-plasma-treated materials. Highlights: Vacuum sealing significantly slowed down the deactivation of plasma-optimized surface energy of AA6061 and CFRP-PA66. Vacuum sealing preserved hydrogen-bonded carbonyl groups on the plasma-treated CFRP-PA66 surface. Vacuum sealing protected over-oxidation of carbon to carbonate on AA6061 surface after the plasma treatment. In the interface between adherend surfaces and adhesive, hydroxyl groups reacted with dicyandiamide to form amide bonds. Vacuum sealing maintained the plasma-enhanced Mode I fracture energy of adhesively-bonded AA6061-CFRP-PA66 dissimilar joints.