Just been reading a paper in which the recovery of stiffness in an overstrained bit of cuticle was not, as I have always thought, ascribed to 'stress-softening' (strain amplification in a rubber with carbon black (or other) filler, caused by the rubber molecules going around the stiff particles) but to 'thixotropy' which could also be typified as recoverable shear-thinning, and is a characteristic of (certain?) liquid crystalline systems. Since many (all?) biological materials are liquid crystals at some time in their life, and many (all?) show 'stress-softening', I wonder if this really says that a (significant?) part of recovery from injury is some sort of recovery of a previous-to-injury liquid crystalline order? Would this recovery of order require less energy than the sort of recovery that we normally think of in technology, which requires external sources of glue, weld, etc?
Julian Vincent
|