A lobster's shell is pretty tough. But the transparent material on the underside of its tail may be even more amazing: Lab tests show the thin, stretchy substance is as sturdy as the rubber used to make tires.
Like the shell surrounding a lobster's body, the flexible material on the underside of the crustacean's tail contains chitin, a fibrous material found in the exoskeletons of many insects and crustaceans. But the team's tests revealed the substance is about 90% water, which lends the material elasticity. It also has a plywoodlike arrangement or microscopic layers, each with chitin fibers running largely in one direction, but with those in neighboring layers running in somewhat different orientations. This same sort of arrangement helps give plywood consistent strength in several directions that a single layer of wood doesn't have, the researchers note.
The layered membrane is somewhat floppy and stretches to almost twice its normal length before it starts to stiff. , the team reports in a forthcoming issue of Acta Biomaterialia . Stretching the material further makes it even stiffer, they note. Overall, the material is as tough as those used for make garden hoses, tires and conveyor belts. Another advantage of the layered arrangement of the membrane: Cuts or gouges that penetrate only a few outer layers do not typically propagate into the intact layers, which renders the material "fault tolerant."
Similar materials could be used to make flexible joints, such as elbows and knees, an armor or hard suits, the researchers suggest.