Volume 78, Number 5, June 2007
Article Number 56005
Number of page(s) 5
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 22 May 2007
EPL, 78 (2007) 56005
DOI: 10.1209/0295-5075/78/56005

A local damage model for anomalous high toughness of double-network gels

Y. 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 $100\,{\rm J}/{\rm m}^{2}$. This is consistent with the experimental value $\sim 400\,{\rm J}/{\rm m}^{2}$.

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