View Journal Article: Relation of Swelling and Tg Depression to the Apparent Free Volume of a Particle-Filled Epoxy-based Adhesive
Chiang, M. Y. and Fernandez-Garcia, M. (2003). Relation of Swelling and Tg Depression to the Apparent Free Volume of a Particle-Filled Epoxy-based Adhesive. Journal of Applied Polymer Science87 (9). 1436-1444.
The effect of hygrothermal aging on a particle-filled, epoxy-based adhesive was studied using a gravimetric sorption technique. This study has explored moisture sorption
characteristics as well as the associated behaviors of swelling and the depression of the glass transition temperature (Tg). We observed that the diffusion of water in this adhesive has a
non-Fickian behavior, and the depression of Tg proceeds to a definite value that is independent of the final equilibrium water content of the system. Our observations suggest that water diffuses
into the polymer in a dualsorption mode, in which water resides in two populations. In one population, water is considered to occupy apparent free volume of the adhesive, and the second population
water infiltrates polymer structure and forms hydrogenbonded clusters. Our results show that hygrothermal aging temperature and swelling do not alter the apparent free volume of this adhesive. We
conclude that the constant value of Tg depression at saturation implies that only water in the apparent free volume is responsible for the Tg depression, whereas the swelling proceeds through the
formation of hydrogen bonds in the adhesive.
Wiley Periodicals, Inc.
Journal of Applied Polymer Science
Journal of Applied Polymer Science 2003; 87(9): 1436-1444; Sponorship: The support of the Ministerio de Educacion y Cultura of Spain to M.F.-G. for this research is gratefully