Durability of PBI adhesive bonded joints under various environmental conditions

Abstract Structural adhesives are finding increasing use in many applications. However, their utilization at elevated temperature has always been a challenge due to their low thermal and mechanical properties. However, in recent years, the development of high performance polymers have overcome the problem of using adhesive bonding at high temperature to some extent. Polybenizimidazole (PBI) is one such recently emerged high performance polymer with excellent thermal and mechanical properties. It has a tensile strength of 160 MPa and a glass transition temperature (Tg) of 425 °C. Due to its excellent thermal and mechanical properties, it has the potential to be used as an adhesive under various environmental conditions. In the present work, efforts are devoted to explore the potential of using PBI at high temperature and in hot-wet environmental conditions. M21 and DT120 epoxy based carbon fiber composite bonded joints were prepared and tested. Both M21/carbon composite and DT120/carbon composite have exhibited a reduction in joint strength of about 16% and 25% respectively after 1000 h of conditioning in a hot-wet environment. However, a reduction in lap shear strength of 52% and 56% is observed when composite bonded joints were tested at 80 °C.