Exposure to environmental factors, especially moisture, is recognized as the major cause of degradation of the adhesive joints. In this work, complementing a previous study on exposure to moisture, single lap joints were subjected to immersion in water, up to five weeks, at room temperature and 50 °C. The material of the adherends was mild steel, the adhesive was a bi-component epoxy. The specimens were fabricated using the open-face technique. Mechanical testing at the end of the relevant period of immersion showed an initial loss of ultimate load, after one week at 50 °C or two at room temperature; then, the strength remained practically constant over the remaining time. The loss was more accentuated after immersion at 50 °C, about 70%, than at room temperature, about 30%. Also a reduction in stiffness of the joints was measured, again dramatic (about 70%) after immersion at 50 °C, moderate (about 10%) after room temperature immersion. Optical examination, performed before closing the open-face specimens and after mechanical testing, showed that the major damage mechanism was the formation of blisters filled by liquid at the primary adherend / primary adhesive interface, causing the failure mode to change from cohesive to interfacial.

Degradation of Epoxy-Steel Single Lap Joints Immersed in Water / Goglio, Luca; Rezaei, Mohsen. - In: JOURNAL OF ADHESION. - ISSN 0021-8464. - STAMPA. - 91:8(2015), pp. 621-636. [10.1080/00218464.2014.948614]

Degradation of Epoxy-Steel Single Lap Joints Immersed in Water

GOGLIO, Luca;REZAEI, MOHSEN
2015

Abstract

Exposure to environmental factors, especially moisture, is recognized as the major cause of degradation of the adhesive joints. In this work, complementing a previous study on exposure to moisture, single lap joints were subjected to immersion in water, up to five weeks, at room temperature and 50 °C. The material of the adherends was mild steel, the adhesive was a bi-component epoxy. The specimens were fabricated using the open-face technique. Mechanical testing at the end of the relevant period of immersion showed an initial loss of ultimate load, after one week at 50 °C or two at room temperature; then, the strength remained practically constant over the remaining time. The loss was more accentuated after immersion at 50 °C, about 70%, than at room temperature, about 30%. Also a reduction in stiffness of the joints was measured, again dramatic (about 70%) after immersion at 50 °C, moderate (about 10%) after room temperature immersion. Optical examination, performed before closing the open-face specimens and after mechanical testing, showed that the major damage mechanism was the formation of blisters filled by liquid at the primary adherend / primary adhesive interface, causing the failure mode to change from cohesive to interfacial.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2585562
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