The Effect of Two Types of Cross-Linking on Some Mechanical Properties of Collagen

Samples of collagen were cross-linked by two different methods: (a) glutaraldehyde and (b) a combination of dehydrothermal treatment and cyanamide. The elastic modulus, the ultimate tensile strength (fracture stress), strain to failure, work of fracture, and fracture toughness were measured before and after cross-linking in ambient laboratory conditions, and during immersion in water. These tests were all performed over a range of strain rates.

For collagen tested in the wet condition, it was found that cross-linking increased the elastic modulus from approximately 25–30 MPa, to between 55 and 60 MPa, but there was little effect on fracture stress, and strain to failure was reduced. The work of fracture of the collagen decreased on cross-linking. Cross-linking had the same effect on the elastic modulus, fracture stress, and strain to failure of dry collagen, but the work of fracture was unaffected. In conclusion, cross-linking increased the elastic modulus, reduced the strain to failure, and had little effect on the fracture stress of collagen under the present experimental conditions.