Effect of climate exposure on mechanical performance of uncured ahdesive joints

Sammanfattning: Adhesive bonding has become an essential joining method in the automotive industry specially with the recent focus on lightweight reduction. A major limiting factor to the widespread implementation of this joining method is concerns about environmental durability. Many research projects have been conducted to investigate the effect environmental exposure on cured adhesive joints, however, the effect that this exposure has on uncured bonds has been overlooked. This study, conducted in collaboration with Volvo cars, aims to investigate the degradation of mechanical properties caused by environmental exposure on uncured bonds and to provide practical recommendations on how to minimize its detrimental effect.  To achieve these objectives adhesive joints were manufactured by a crash resistant epoxy based adhesive and exposed to different climates for different ageing times and conditions. Afterwards, curing and mechanical testing were performed to assess the degradation of mechanical properties: shear strength, peel strength and fatigue life. Analysis of the results showed harsher climates to be linked to an increase in degradation of mechanical properties, an open bond exposure to accelerate the degradation process. Defects were introduced as pores and a decrease in adhesion to the adherend. Practical recommendations were made to minimize open bond exposure and harsh climates.