title: From thermally activated to viscosity controlled fracture of biopolymer hydrogels.
abstract: We report on rate-dependent fracture energy measurements over three decades of steady crack velocities in alginate and gelatin hydrogels. We evidence that irrespective of gel thermoreversibility, thermally activated "unzipping" of the noncovalent cross-link zones results in slow crack propagation, prevailing against the toughening effect of viscous solvent drag during chain pull-out, which becomes efficient above a few mm s(-1). We extend a previous model [T. Baumberger et al., Nat. Mater. 5, 552 (2006)] to account for both mechanisms and estimate the microscopic unzipping rates.
authors.affiliation: INSP, UPMC Univ Paris 06, CNRS UMR 7588, 140 rue de Lourmel, 75015 Paris, France.
authors.forename: T
authors.initials: T
authors.lastname: Baumberger
authors.forename: O
authors.initials: O
authors.lastname: Ronsin
mesh_terms: D000464:Alginates / Q000737:chemistry; D001704:Biopolymers / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry / Q000145:classification; D005780:Gelatin / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D006860:Hydrogen Bonding; D013696:Temperature; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D000464:Alginates; D001704:Biopolymers; D003432:Cross-Linking Reagents; D004573:Electrolytes; D006603:Hexuronic Acids; D020100:Hydrogels; D014867:Water; D020723:Glucuronic Acid; D005780:Gelatin