Experimental and numerical analysis of cyclic aging in an epoxy-based adhesive

• Published in: Polymer testing Vol. 91; p. 106789
• Main Authors: Moazzami, M., Ayatollahi, M.R., Akhavan-Safar, A., da Silva, L.F.M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2020
• Subjects: Cyclic aging; Epoxy adhesive; Fick's law; Moisture absorption; Numerical analysis; Moisture absorption; Numerical analysis; Cyclic aging; Fick's law; Epoxy adhesive
• ISSN: 0142-9418; 1873-2348
• DOI: 10.1016/j.polymertesting.2020.106789

The strength and durability of adhesive joints in different applications is of special concern where aging can significantly influence the joint permanence. Aging of adhesive joints is very crucial in industries where the joints are exposed to variable environmental conditions during their life. Due to the aging, the mechanical properties of the adhesive layer, interfacial bonding properties and substrates mechanical performance (in case of composite substrate), change. In real applications, the aging conditions is cyclic where the joints frequently experience aging and drying conditions. This article investigates the mechanical behavior and water absorption properties of an epoxy based adhesive in bulk form, subjected to cyclic aging conditions. The effect of cyclic aging on different parameters such as the rate of moisture absorption and desorption, stress-strain curve, glass transition temperature (Tg) have been studied. In the numerical section the parameters of moisture diffusion obtained experimentally were used to simulate the moisture distribution in dog-bone specimens. The experimental results show that in cyclic aging conditions the moisture diffusion constant and the maximum moisture content increase with aging cycles. Also it was found that the mechanical properties such as the elastic modulus and the tensile strength in saturation states decrease with increasing the aging cycles. •Moisture diffusion was investigated for an epoxy adhesive exposed to cyclic aging.•Diffusion constant and maximum moisture content of epoxy increased during cyclic aging.•During absorption periods, the elastic modulus and tensile strength of epoxy decreased.•Elastic modulus and tensile strength increased with time while drying the epoxy adhesive.•The amount of Tg measured at the end of cycles decreased with the number of aging cycles.