Accelerated test method for water resistance of adhesive joints by interfacial cutting of open-faced specimens

ABSTRACT

Conventional test methods to evaluate the water resistance of adhesive joints are time-consuming. To reduce experimental time, open-faced specimens have been proposed. Numerical analysis indicated that the water absorption of an open-faced specimen was 3000 times faster than that of a conventional closed specimen. The strength of the interface between the adhesive and the adherend of the open-faced specimen was measured using the interfacial cutting method in this research. The resultant strength decreased with respect to immersion time in water, and this trend accelerated with an increase in the water temperature. When water was absorbed at temperatures below the glass transition temperature (T_g) of the adhesives, the strength was constant at 80–90% of the initial value in the first stage, and it decreased proportionally with logarithmic immersion time in the following stage. At water absorption above T_g, the interfacial strength initially proportionally decreased with the logarithmic immersion time. After the initial absorption, the slopes changed, and the strength slowly decreased. After further immersion for 59 days at 87°C, a sharp decrease in strength occurred. The reducing behaviour of the interfacial strength fitted the Arrhenius plot, which provided the estimated time to reach a specific strength by water immersion.

KEYWORDS:

• Water absorption
• water immersion
• open-faced specimen
• interfacial cutting
• Arrhenius plot

Acknowledgements

This paper is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). We express our appreciation to the CEMEDINE CO., LTD. for the provision of materials and information.

Additional information

Funding

This work was supported by the New Energy and Industrial Technology Development Organization.