New elements for the understanding of the anaerobic adhesives reactivity

The reactivity of anaerobic adhesives is still a controversial subject even if some deep research is carried out from the beginning of the 1990s. In this article, we report some new elements on the initiation mechanism of anaerobic adhesives with regard to existing assumptions proposed in the literature. Our investigation consisted in studying the rheological behaviour as a function of time for model adhesive formulations in contact with metallic copper. Kinetics of reaction are expressed from the experimental data as a function of the concentration in different species and their partial order. The predominant character — compared to the effect of absence of oxygen — of metallic catalysis due to the copper at its lower oxidation state is highlighted as well as the redox decomposition of the peroxide initiator. The formation of a metallic salt during the initiation is also highlighted and appears to be an crucial element for the reaction.