Detachment of a polyurethane ring glued on a metallic support

The ring to be tested consisted of two attached parts: a metallic ring and a polymeric ring. Our laboratory performed some exhamination of the adhesive layer on each the two attached surfaces, after being detached.
Photo of SEM investigation on the metallic part of ringPhoto of SEM investigation on the metallic part of ring
Photo of SEM investigation on the metallic part of ring
According to the findings through the SEM investigation, the adhesive is present on both surfaces (metallic and polymeric).

The thermogravimetric test (TGA) has been made on a specimen where the adhesive was still present. The TGA test has shown that the maximum percentage of mass loss is related to the mass of polyurethane part. The rest could be attributed to the mass loss due to the wax for detaching and a layer of graphite.

This layer of graphite is a lubricant material producing easier detachment and at the same time can be the cause of a defecting adhesion. Different aspects have to be checked during the adhesion procedure: temperature, humidity, pressure, oil or grease precence on surface etc..

Dott.ssa Emma Martin Gonzales
Sigla.com - Internet Partner