Exposure to water either directly or via humidity can seriously decrease the strength of an adhesive joint. Although moisture can attack in several ways, it is most often the adhesive-adherent interface that is weakened. The amount of moisture in the adhesive can be measured, but the concentration of moisture at the interface may be quite different. Using a new technology that measures the moisture concentration, Don will examine the factors that influence durability: the nature of the adhesive, the type of substrate and the concentration of water. The results show an important tradeoff between joint strength and durability. Based on this knowledge, approaches to improving this tradeoff will be discussed.
Donald Hunston is an independent consultant and a Guest Researcher in the Engineering Laboratory of the National Institute of Standards and Technology (NIST). He has studied adhesives and composites for over 30 years, first in the Adhesives and Composites Section of the Naval Research Laboratory and then as Leader of the Polymer Composites Group at NIST. His work spans many aspects of composites, adhesives, and sealants but mechanics is a particular focus. He is active in the Adhesion Society, serving twice as Vice President, and has published over 270 scientific articles and reports. In 1999, he was selected as a Robert L. Patrick Fellow of the Adhesion Society.