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Relation of swelling and T g depression to the apparent free volume of a particle‐filled, epoxy‐based adhesive
Author(s) -
Chiang Martin Y. M.,
FernandezGarcia Marta
Publication year - 2002
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.11576
Subject(s) - swelling , adhesive , gravimetric analysis , materials science , composite material , epoxy , diffusion , volume (thermodynamics) , sorption , polymer , population , glass transition , particle (ecology) , absorption of water , polymer chemistry , hydrogen bond , chemistry , thermodynamics , molecule , organic chemistry , adsorption , physics , demography , oceanography , layer (electronics) , sociology , geology
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 ( T g ). We observed that the diffusion of water in this adhesive has a non‐Fickian behavior, and the depression of T g 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 dual‐sorption 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 hydrogen‐bonded 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 T g depression at saturation implies that only water in the apparent free volume is responsible for the T g depression, whereas the swelling proceeds through the formation of hydrogen bonds in the adhesive. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1436–1444, 2003