Flame and silane treatments for improving the adhesive bonding characteristics of aramid/epoxy composites

A fast and cost-effective surface treatment with flame and silane coupling agent treatments has been developed for the surface treatment of aramid/epoxy composite faces to improve the adhesive bonding characteristics of lightweight sandwich stealth radome structures. The flame treatment was performed with propane gas, and the silane treatment was performed with γ-methacryloxypropyltrimethoxy silane (γ-MPS) and γ-aminopropyltriethoxy silane (γ-APS) under different treatment conditions. The contact angles of the flame-treated aramid/epoxy composites and the single-lap shear strengths of the adhesive joint composed of the aramid/epoxy composite adherend and epoxy adhesive were measured and compared with those treated with argon plasma and mechanical abrasion. In addition, the surfaces were analyzed with atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) to characterize the mechanical and chemical interactions of the aramid/epoxy composite with the epoxy adhesive.