Structural methacrylate/epoxy based adhesives for aluminIum joints

The aim of this work was to investigate the influence of elastomer and monomer concentration on the properties of methacrylate/epoxy based adhesive formulations using a Plackett-Burman experimental design. The adhesive formulations were developed in order to bond non-treated aluminium panels. Their chemical structure was analysed by Fourier transformed infrared spectroscopy (FTIR) and the thermal behaviour by thermogravimetry (TGA) and differential scanning calorimetry (DSC) in comparison to a commercial adhesive. After room temperature mixing, time and temperature of the curing reaction were measured. Further, non-treated aluminium single-lap joints were adhesively bonded and their shear strengths were evaluated. The formulations showed chemical structure similar to a commercial adhesive but the thermal behaviour was quite distinct. The commercial adhesive cured slower than the developed adhesive formulations which can directly affect the bonding quality. However, some formulations showed higher shear strengths than the commercial one, but all with adhesive failure mode. The adhesive formulations with elastomers in methacrylate part showed the highest shear strengths.