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Correlation between sub‐ T g relaxation processes and mechanical behavior for different hydrothermal ageing conditions in epoxy assemblies
Author(s) -
Chevalier M.,
Dantras E.,
To C.,
Guigue P.,
Lacabanne C.,
Puig C.,
Durin C.
Publication year - 2009
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.31253
Subject(s) - materials science , epoxy , composite material , adhesive , relaxation (psychology) , moisture , molecular dynamics , accelerated aging , hydrothermal circulation , chemical engineering , chemistry , computational chemistry , psychology , social psychology , layer (electronics) , engineering
Abstract The aim of this study is to understand aging phenomena by monitoring physical parameters after real and simulated aging experiments. This study focuses on aluminum‐epoxy assemblies, which are commonly used on spacecraft structures. Different samples are submitted to simulated aging tests. Influence of temperature and moisture is analyzed. Evolution with aging is characterized at two different scales. The macroscopic behavior of the assemblies is studied by single lap shear test. A decrease in the shear rupture stress is observed with increasing temperature and relative humidity. It is demonstrated that temperature has more important influence. The molecular behavior in the adhesive joint is studied by dynamic dielectric spectroscopy measurements. This experiment gives access to molecular mobility in the adhesive. Dipolar entities are identified as evolving with aging conditions. The temperature is more effective than moisture at this scale. An interpretation of the molecular mobility before and after aging shows that water is an important parameter of this study. A link between mechanical and molecular behavior with hydrothermal aging is found. The decrease of mechanical properties occurs while failures become interfacial. In the same time, the interactions between hydroxyether and water increase. The evolution of the macroscopic behavior of the bonded assemblies is due to this combination observed at different scales. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010