Enhancement of saltwater ageing behavior of nanocomposites and lap joints with boron nanoparticles

The presented research aims to enhance the ageing performance of nanocomposites and bonded joints in the saltwater medium with boron nanoparticle doping. Epoxy nanocomposites and bonded aluminum 2024-T3 joints doped with 2 wt% silane-functionalized boron carbide (B4C) and boron nitride (BN) nanoparticles and undoped were produced for that purpose. The produced samples were immersed in a saltwater (10% NaCl) solution at 40 degrees C for 480, 960 and 1440 h. By performing the weight change test, Fourier transform infrared (FT-IR) spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), tensile test and scanning electron microscope (SEM), the research aimed to comprehensively assess the changes in the properties of nanocomposites and lap joints after exposure to saltwater ageing, shedding light on the effectiveness of boron nanoparticle doping in improving their performance in saltwater environments. The result showed that thanks to the anti-plasticisation behaviour of nanoparticles, 18.4% and 19.6% higher Tg values were obtained in B4C and BN-doped nanocomposites after 1440 h of ageing, respectively. Similarly, the static tensile strength of the undoped composite decreased by 22%, while B4C and BN-doped nanocomposites decreased by 15% and 14%, respectively, at the end of ageing. After 1440 h, the storage modulus of undoped, B4C and BN-doped nano-composites decreased by 24.2%, 15.3% and 11.9%, respectively. It was found that B4C and BN-doped bonded joints performed superior mechanical properties compared to their undoped counterparts. The joints doped with B4C and BN nanoparticles carried 50% and 52% higher loads than the undoped joint.