For an adhesive bond to be useful, it must not only withstand the mechanical forces that act on it, but it must also resist the elements to which it is exposed during service. One of the most degrading elements for organic adhesives is heat. Much has been done in recent years to synthesize high temperature polymer systems for structural adhesives. These resins will be briefly reviewed here. However, this paper will mainly discuss how structural adhesive formulators can help to reduce the harmful effects of heat.
Effects of Elevated Service Temperature
All polymeric materials are degraded to some extent by exposure to elevated temperature. Not only do elevated temperatures lower short-term physical properties, but properties will also likely degrade with prolonged thermal aging. Thus, several important questions need to be asked of an adhesive if high service temperatures are expected.
* What is the maximum temperature that the bond will be exposed to in service?
* What is the average temperature to which the bond will be exposed?