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Title: Mechanisms of degradation in adhesive joint strength: Glassy polymer thermoset bond in a humid environment

Journal Article · · International Journal of Adhesion and Adhesives
 [1];  [1];  [1];  [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
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The degradation in the strength of napkin-ring (NR) joints bonded with an epoxy thermoset is evaluated in a humid environment. While adherend composition (stainless steel and aluminum) and surface preparation (polished, grit blasted, primed, coupling agent coated) do not affect virgin (time=0) joint strength, they can significantly affect the role of moisture on the strength of the joint. Adherend surface abrasion and corrosion processes are found to be key factors in determining the reliability of joint strength in humid environments. In cases where surface specific joint strength degradation processes are not active, decreases in joint strength can be accounted for by the glass transition temperature, Tg, depression of the adhesive associated with water sorption. Under these conditions, joint strength can be rejuvenated to virgin strength by drying. In addition, the decrease in joint strength associated with water sorption can be predicted by the Simplified Potential Energy Clock (SPEC) model by shifting the adhesive reference temperature, Tref, by the same amount as the Tg depression. When surface specific degradation mechanisms are active, they can reduce joint strength below that associated with adhesive Tg depression, and joint strength is not recoverable by drying. Furthermore, a critical relative humidity (or, potentially, critical water sorption concentration), below which the surface specific degradation does not occur, appears to exist for the polished stainless steel joints.

Research Organization:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC04-94AL85000
OSTI ID:
1236247
Alternate ID(s):
OSTI ID: 1422627
Report Number(s):
SAND-2014-16234J; 533734
Journal Information:
International Journal of Adhesion and Adhesives, Vol. 63, Issue C; ISSN 0143-7496
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 6 works
Citation information provided by
Web of Science

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Cited By (1)

Environmental effect on the fatigue degradation of adhesive joints: A review journal April 2016

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Related Subjects

36 MATERIALS SCIENCE
adhesion
degradation
humidity
mechanism
viscoelasticity