Use of dielectric spectroscopy to assess adhesively bonded composite structures, Part II: Dielectric study

A study of the sorption and desorption of moisture in a structural adhesively bonded composite structure using low- and high-frequency dielectric spectroscopy is reported when the adhesive is subjected to a hot and wet environment. As water penetrates the structure, variations in the dielectric permittivity and dielectric loss can be used to understand the nature of the absorption process. A new dielectric tool is introduced to aid interpretation of the dielectric data based on the Kirkwood-Fröhlich equation of the dipolar activity. The data are correlated with gravimetric and dynamic mechanical thermal analysis of the adhesive during exposure to moisture reported in Part I of this series of three articles.