APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010;
Portland, Oregon
Session X18: Focus Session: Polymer Network Mechanics II
2:30 PM–5:30 PM,
Thursday, March 18, 2010
Room: B117
Sponsoring
Unit:
DPOLY
Chair: Al Crosby, University of Massachusetts, Amherst
Abstract ID: BAPS.2010.MAR.X18.4
Abstract: X18.00004 : Toughening Mechanism of Double Network Hydrogels*
3:06 PM–3:42 PM
Preview Abstract
Abstract
Author:
Jian Ping Gong
(Hokkaido University)
The fundamental toughening mechanism of DN gels [1] is of great
interest to researchers. Extensive experimental and theoretical
studies have been performed to explain this mechanism [2-7].
Yielding and necking deformation [2] that was observed through
tensile tests and rate-independent hysteresis [3] observed
through cyclic loading tests have indicated that DN gels can
accumulate internal damage before the suffering macroscopic
fracture; after damage accumulation, the DN gels become much
softer. We assume that on the microscopic level, yielding is
caused by the partial breakage and fragmentation of the brittle
first network and interconnection among the fragments by the
polymer chains of second network [2]. Brown [4] and Tanaka [5]
have proposed similar models that can qualitatively explain
the anomalously high fracture energy, assuming that the DN gel is
locally damaged (yielded) around the crack tip and that the
energy dissipated for damage accumulation enhances the effective
fracture energy. Using AFM measurements [6] and 3D color laser
microscope[7], we successfully detected the existence of softened
regions, of several hundreds $\mu $m in thickness,
at the crack tip just below the fracture surfaces, which supports
the assumption of localized damage accumulation. A linear
relationship between the thickness of the softened yielding zone
and the fracture energy of the gel was observed, which is in
agreement with the local yielding zone explanation.
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[1] Gong, J. P.; Katsuyama, Y.; Kurokawa, T.; Osada, Y. Adv.
Mater. 2003, 15, 1155.
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[2] Na Y.H., Tanaka Y., Kawauchi Y., Furukawa H., Sumiyoshi T.,
Gong J. P., Osada Y., Macromolecules 2006, 39(14), 4641.
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[3] Webber, R. E.; Creton, C.; Brown, H. R.; Gong, J. P.
Macromolecules 2007, 40, 2919.
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[4] Brown, H. R. Macromolecules 2007, 40, 3815.
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[5] Tanaka, Y. Euro Phys. Letter. 2007, 78, 56005.
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[6] Tanaka Y.; Kawauchi Y.; Kurokawa T.; Furukawa H.; Okajima T.;
Gong J. P. Macrom. Rapid Comm. 2008, 29(18), 1514.
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[7] Yu, Q. M.; Tanaka, Y.; Furukawa, H.; Kurokawa, T.; Gong, J.
P. Macromolecules, 2009, 42(12), 3852.
*This research was financially supported by a Grant-in-Aid for Specially Promoted Research (No. 18002002) from the Ministry of Education, Science, Sports and Culture of Japan.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.X18.4