Abstract
Diffusion of water into adhesives cause to reduce the strength of the bonded structures. In case of optical devices, a problem in the use of adhesive bonding has been its propensity to absorb moisture and swell. A practical and accurate method of predicting moisture absorption and its effects is essential. In this study, deformation generated by humidification and dehumidification was monitored by using the bimetal specimen. 2-part room temperature cured epoxy adhesive and copper substrate were used. Temperature on the surface of adhesive keeps at a fixed temperature and humidity was synchronized with laboratory environment. It was cleared that deformation was proportional to relative humidity. Moreover, time dependent distribution of moisture in a adhesive was calculated by the Fickean diffusion law and deformation was calculated by the Hook's law and the coefficient of moisture expansion (CME). There is good agreement between experimental and calculated results.
