6. On the relationship between physical crosslinking density and fracture toughness in gelatin gels

M. CZERNER; J. F. MARTUCCI; L.A. FASCE; R.A. RUSECKAITE; P.M. FRONTINI

Conferencia; 6th International Conference on Polymer Behaviour (ICPB6); 2014

Gelatin forms physical gels in which the crosslinking points (junction zones) are created by secondary ordered structures similar to the triple-helix arrangements in native collagen. It is well documented that stiffness is dominated by triple-helix concentration. This work explores whether fracture toughness is also governed by triple-helix concentration. Several gel samples differing in gelatin concentration, gelatin source (bovine or porcine) and solvent (water/water-glycerol/water-sorbitol) are studied. Fracture toughness is determined by the Wire Cutting method at 100mm/min and the triple-helix concentration through the number-average molecular weight between crosslinking points. Higher fracture toughness values are obtained by increasing gelatin concentration, adding glycerol and sorbitol as co-solvents and using porcine rather than bovine gelatin. All these observations are consistent with the development of a more physically crosslinked structure in the gels. Our results identify the relevance of triple helix-concentration as key parameter controlling fracture toughness of gelatin gels.