Adhesive Joint Durability Assessed Using Open-faced Peel Specimens

• Published in: The Journal of adhesion Vol. 65; no. 1-4; pp. 239 - 257
• Main Authors: Moidu, Abduljaleel K., Sinclair, Anthony N., Spelt, Jan K.
• Format: Journal Article
• Language: English
• Published: Basingstoke Taylor & Francis Group 01.01.1998; Taylor and Francis
• Subjects: Adhesive joints; adhesive plasticization; Ageing; Applied sciences; cohesive failure; environmental degradation; Exact sciences and technology; fracture energy; interfacial failure; peel test; Physical properties; plastic dissipation; Polymer industry, paints, wood; Properties and testing; Technology of polymers; Scanning electron microscopy; Stress analysis; Fracture mechanics; Peel strength; Stress strain relation; Adhesive joint; Epoxy resin; Weathering; Durability; Chemical degradation; Strength; Crack propagation
• ISSN: 0021-8464; 1563-518X; 1545-5823
• DOI: 10.1080/00218469808012248

This paper presents an investigation of the durability of two aluminum-epoxy adhesive systems by means of open-faced peel specimens. A peel analysis model was used to determine the fracture energy from the peel data. Both wet and dry peel tests were conducted in order to distinguish between the reversible and the permanent effects of water. The effects of water on the cohesive properties of the adhesives were also assessed by tension tests. It was found that, for the two-part epoxy adhesive, which plasticized to a large extent, the peel testing should be carried out in a dry state to assess the interfacial weakening. It was also observed that the two-part adhesive was much stiffer in the dry, degraded state, and it was important to take account of such permanent changes in the cohesive properties associated with water uptake when determining the fracture energy from the peel data. In contrast, the one-part epoxy system did not suffer from appreciable cohesive changes, either reversible or permanent. In this case, both wet and dry failure loci were interfacial, and some of the interfacial damage was found to be reversible. Finally, surface analyses of the peel failure surfaces were carried out, and the formation of micro-debonds was identified as a possible mechanism of degradation for the two-part system.