Adhesives in demanding applications

Structural adhesives are nowadays employed extensively in structural engineering applications where advantage is made of many outstanding attributes, most notably their ability to confer reduced weight, improved fatigue performance together with reduced production and life cycle costs. Increasingly in recent years, attempts have been made to employ bonded structures in harsh environments. In this article an attempt is made to consider the demanding environments which bonded joints are frequently required to resist, focusing principally on hot/wet and high temperature conditions. With the former, the ways in which water can adversely affect joint behaviour are highlighted and the factors, such as nature of adhesive and surface treatment, crucial to optimum joint performance are discussed. Adhesive joints in high temperature environments are discussed in terms of early high temperature adhesives, designed with little thought to processability, together with more recent developments in high temperature adhesives where processability has been 'engineered' into the polymer structure.