The tensile properties and mode of fracture of elastoidin.

The tensile properties and mode of fracture of elastoidin, a collagenous protein fibre from the fins of sharks, were compared with those of rat tail tendon fibres, considered to be a pure form of collagen. Elastoidin fibres were stronger than tendon in the dry state whereas the opposite was observed for fibres tested in the wet state. However, elastoidin was stiffer than tendon whether dry or wet. Scanning electron micrographs of the cross sections and fractured surfaces revealed that elastoidin fibres consisted of fibrils of varying diameter arranged in a lamellar fashion. From the nature of the fractured surfaces, it could be deduced that the primary failure mechanism for elastoidin was probably through a fissuring of the structure.