Determination of mechanical properties of bonded joints joined with fibre-reinforced adhesive

The rapid advancement of technology, particularly in aerospace and other high-tech industries, has intensified the demand for high-performance materials and innovative joining techniques. Adhesive bonding has emerged as a crucial method for assembling composite structures in response to these challenges. This doctoral research investigates the reinforcement of adhesives with carbon fibers and examines the effects of chemical surface treatments on the mechanical performance of adhesive joints. In this study, two types of adhesives-rigid and flexible-were modified by incorporating carbon fibers at weight fractions of 0.5%, 1%, 2%, and 3%. These fibers underwent surface treatments using acetone (C3H6O), sulfuric acid (H2SO4), nitric acid (HNO3), hydrochloric acid (HCl), and a nitric acid/hydrochloric acid (HNO3/HCl) mixture. Additionally, cetyltrimethylammonium bromide (CTAB) adsorption was performed at concentrations of 15, 30, 60, and 90 mg/L. Mechanical tests conducted on single-lap joints fabricated under optimal processing parameters revealed that both chemical surface modifications and CTAB adsorption enhanced the joint strength by 4% to 126%. FTIR and SEM analyses were employed to characterize the morphological changes in fiber surfaces and to assess their influence on bond performance. The findings indicate that CTAB concentrations between 30 and 60 mg/L yield the most significant improvements in mechanical performance.