Fracture of a biopolymer gel as a viscoplastic disentanglement process
  We present an extensive experimental study of mode-I, steady, slow crack dynamics in gelatin gels. Taking advantage of the sensitivity of the elastic stiffness to gel composition and history we confirm and extend the model for fracture of physical hydrogels which we proposed in a previous paper (Nature Materials, doi:10.1038/nmat1666 (2006)), which attributes decohesion to the viscoplastic pull-out of the network-constituting chains. So, we propose that, in contrast with chemically cross-linked ones, reversible gels fracture without chain scission. 
Tristan Baumberger (INSP), Christiane Caroli (INSP), David Martina   (INSP)