Analysis of whitening phenomenon of EPDM article by humid aging

An ethylene–propylene–diene terpolymer (EPDM) article used for a car component was aged in 80°C humid air (60% relative humidity) for 30 days and in 80°C tap water for 7 days. The aged sample surfaces were changed to white. The aged sample surfaces were analyzed using GC/MS, image analyzer, SEM, EDX...

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Bibliographic Details
Published in:Journal of applied polymer science 2012-02, Vol.123 (4), p.2451-2457
Main Authors: Choi, Sung-Seen, Chung, Hye-Seung, Joo, Yong-Tae, Yang, Kyung-Mo, Lee, Seong-Hoon
Format: Article
Language:English
Subjects:
Applied sciences
Calcium
calcium cation
calcium stearate
Carbon black
Cations
Composites
EPDM
Exact sciences and technology
fatty acid
Forms of application and semi-finished materials
Materials science
Polymer industry, paints, wood
Polymers
Stearates
Stearic acid
Tap water
Technology of polymers
Terpolymers
whitening
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Summary:An ethylene–propylene–diene terpolymer (EPDM) article used for a car component was aged in 80°C humid air (60% relative humidity) for 30 days and in 80°C tap water for 7 days. The aged sample surfaces were changed to white. The aged sample surfaces were analyzed using GC/MS, image analyzer, SEM, EDX, and ATR‐FTIR. Calcium stearate was found on the aged sample surface. To confirm the whitening phenomenon, three sulfur‐cured EPDM composites with different reinforcing systems (talc/carbon black, calcium carbonate/carbon black, and clay/carbon black) and one resole‐cured EPDM composite were prepared and aged in 90°C tap water for 7 days. The sulfur‐cured EPDM composites contained stearic acid, whereas the resole‐cured EPDM composite did not contain stearic acid. Whitening occurred in the sulfur‐cured EPDM samples irrespective of the filler systems but the aged resole‐cured EPDM composite surface was not changed. The whitening was due to the formation of calcium stearate as a result of reaction between calcium cation and stearic acid. The calcium cation came from humid air and tap water, while the stearic acid came from the sulfur‐cured EPDM samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
ISSN:0021-8995
1097-4628
1097-4628
DOI:10.1002/app.34826