Characterization of cure profiles of anaerobic adhesives by real-time FT-IR spectroscopy. Part II. Surface activation

Abstract

A real-time Fourier transform-infrared (RT/FT-IR) spectroscopic technique has been used to study the cure profile of surface-activated anaerobic polymerization on metal surfaces at room temperature. The cure characterization of redox polymerization of anaerobic composition on several metal surfaces has been studied which included copper, aluminum, galvanized steel, zinc-plated steel, stainless steel, and passivated stainless steel. The copper surface was found to be the most active surface for initiating the polymerization. The effectiveness of various surface treatments for anaerobic cure was also studied. The results indicated that 316L stainless steel specimens, which have been passivated for corrosion preventive purposes, show an increase in activity for surface-initiated anaerobic polymerization over the specimen without passivation. The anaerobic cure on passivated 316L stainless steel specimens shows a higher ultimate degree of conversion and cure speed than on non-passivated steel. The buffing and passivation treatments produced the most active surface. This increase in surface activity appears to be due to the buffing and passivation treatment, resulting in roughening the surface as well as removing the inert oxide layer and scales. The role of nitric acid/EDTA in the passivation treatment for surface reactivity enhancement has also been discussed. The surface reactivity was evaluated based on the ability to accelerate an anaerobic cure in a real-time mode and has been correlated with the metal type and content in the interface region. The surface texture and metal contents were measured using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively.