Thermal Properties of Adhesives


The thermal properties of adhesives affect the rate of cure, whether the latter is by evaporation, cooling, or chemical reaction. In the latter case cure may not go to completion in the sense that not all monomer is reacted, or may not be possible at all above a ceiling temperature. The heat of polymerization is a useful guide to what may happen.

The glass transition temperature of a cured adhesive is of critical importance, in that although there are both sub-Tg and super-Tg adhesives, crossing Tg in service is not acceptable. Tg also has a role in latex-adhesives forming cohesive films.

Adhesives exhibit a mixture of viscous and elastic properties and obey the WLF equation. This indicates that the fraction of free volume at the glass transition is 2.5%.

Consideration is given to thermal conductivity and thermal expansion, and the thermal breakdown of adhesives.