Forestry 485 Lecture 2-1: Introduction to Adhesion

Adhesion  Adhesion – from the Latin adhaere, “to stick to”  In a practical sense, adhesion is the mechanism by which an adhesive transfers a load from an adherend to the adhesive joint -Packham, 1992

 Adherends=solid materials in the adhesive joint, other than the adhesive  Adhesive=(generally) polymeric materials that exhibit viscoelastic properties; capable of bonding to adherends and transferring load from the adherend to the adhesive joint  Adhesive joint=an assembly made by the use of an adhesive. Also called an adhesive bond. -Pocius, 2002

 “Adhesive bonding is a method by which materials can be joined to generate assemblies. Adhesive bonding is an alternative to more traditional mechanical methods of joining materials, such as nails, rivets, screws, etc.” -Pocius, 2002

 Two primary functions of an adhesive:  1. Adequately bond to the surface of adherends  2. Contribute appropriate mechanical properties upon curing (load transfer)

Advantages and Disadvantages of Adhesive Bonding  Advantages:  Minimize stress concentrations  Viscoelastic behavior of adhesive contributes to absorption of applied mechanical load  Dissimilar materials can be joined

Advantages and Disadvantages of Adhesive Bonding  Disadvantages:  Complex behavior at the surface of adherends; complex behavior of adhesive resin formulations  Adhesion occurs within a composite material; difficult to establish if proper bonding occurs

References  Packham, D Adhesion, p in Handbook of Adhesion. John Wiley and Sons, New York. 570 pages.  Pocius, A Chapter 1, p in Adhesion and Adhesives Technology: An Introduction. Hanser Gardner Publications Inc. Cincinnati, OH. 319 pages.