Measurement of the mechanical properties of structural adhesives in tension and shear over a wide range of temperatures

The aim of this study was to select suitable adhesives for use in a mixed adhesive joint and to measure their mechanical properties over a wide range of temperatures. Three adhesives were selected: a bismaleimide adhesive (Redux 326) for high temperatures and two paste-form epoxies (Hysol EA 9359.3 and Supreme 10HT) for low temperatures. The mechanical properties in tension (dogbone specimens) and in shear (thick adherend shear test) are presented from -55 to 200°C for all three adhesives. Dynamic tests were also carried out to confirm the static modulus results. The correlations between the tensile and the shear properties are reasonable in terms of stiffness and strength but are poor in terms of ductility. In a single-lap joint, Redux 326 is stronger at high temperatures as it becomes more ductile. However, it is very stiff and brittle until 100°C. Supreme 10HT has very good performance up to 100°C. The combination of Redux 326 and Supreme 10HT formed a joint that had a good load carrying capacity from -55 to 200°C.