A local damage model for anomalous high toughness of double-network gelsY. Tanaka
Creative Research Initiative Sousei, Hokkaido University - Sapporo 001-0021, Japan
received 19 January 2007; accepted in final form 25 April 2007; published June 2007
published online 22 May 2007
We present a phenomenological model for anomalously high fracture energy of double-network (DN) gels, which consist of a substantially cross-linked polyelectrolyte gel (first network) and of a quite poorly cross-linked neutral polymer (second network) penetrating into the first network (GONG J. P., KATSUYAMA Y., KUROKAWA T. and OSADA Y., Adv. Mater., 15 (2003) 1155). The model assumes that the material locally softens around crack tip due to damage of the first network, and then the crack extends within the softened zone. An order estimation indicates that energy dissipation by the softening greatly exceeds the "bare fracture energy" of the softened material, and that the effective fracture energy can reach the order of . This is consistent with the experimental value .
61.41.+e - Polymers, elastomers, and plastics.
62.20.Mk - Fatigue, brittleness, fracture, and cracks.
81.05.Qk - Reinforced polymers and polymer-based composites.
© Europhysics Letters Association 2007