Behaviour of environmentally degraded epoxy adhesives as a function of temperature. Issue 1 (28th January 2017)

• Record Type: Journal Article
• Authors: Viana, G.; Costa, M.; Banea, M. D.; da Silva, L. F. M.
• Is Part Of: Journal of adhesion. Volume 93:Issue 1/2(2017)
• Page Start: 95
• Page End: 112
• Publication Date: 2017-01-28
• Subjects: Moisture degradation -- temperature tests -- tensile tests; Adhesion -- Periodicals; 541.33
• DOI: 10.1080/00218464.2016.1179118
• Languages: English
• ISSNs: 0021-8464

Abstract

ABSTRACT: Structural adhesives are increasingly being used in the aerospace and automotive industries. They allow for light weight vehicles, fuel savings, and reduced emissions. However, the environmental degradation of adhesive joints is a major setback in its wide implementation. Moisture degradation of adhesive joints includes plasticization, attacking of the interface, swelling of the adhesive and consequent creation of residual stresses. This may lead to reversible and irreversible damage. The main factors affecting the strength of adhesive joints under high and low temperatures are the degradation of the adhesive mechanical properties and the creation of residual stresses induced by different coefficients of thermal expansion (between the adhesive and the adherends). The effect of the combined effect of moisture and temperature is not yet fully understood. The aim of this study is to shed light on this subject. In this work bulk water absorption tests were conducted at different moisture conditions in order to assess the diffusion coefficient, maximum water uptake, and glass transition temperature. Aged and unaged small dogbone tensile specimens were tested under different temperature conditions. The glass transition temperature of the adhesives as a function of the water uptake was assessed. The aim is to determine the evolution of the properties of two epoxy adhesives as a function of two variables (environmental temperature and moisture).