THE IMPACT RESISTANCE OF CTBN-MODIFIED EPOXY ADHESIVE JOINTS

The wide use of structural adhesives by cars'manufacturers, lays down the problem of the impact resistance of a rubber-modified epoxy-bonded steel joint. An experimental device, which allows us to reach high st rain rates under different failures modes (mode I, mode II, mode I+II) and under different temperature conditions, has been developed. To al low the use of fracture mechanics, to study the substrate influence, a dhesive specimens have been realized with an interfacial defect. The m icrostructure analysis of adhesive joints, using thermal characterizat ion and infra-red-spectroscopy, have shown differences between joint t hicknesses and between joint cures schedules, due to the hardening and phase separation processes. These morphological differences are immed iately followed by modifications in energy release rate results. There is cause to believe that this phenomenon is due to the relationships between structure and mechanical properties.