OPTICAL RHEOMETRY OF SILK IN AQUEOUS LIBR SOLUTION

The rheo-optical response of solutions of silk in aqueous 9 M LiBr of concentrations ranging from 7.5 to 15 wt % was investigated. These sam ples were found to be birefringent under flow, with the steady state b irefringence having a concentration scaling of c(3.9). This scaling be havior suggests a wormlike conformation of the silk molecules in solut ion. The relaxation was fast, and Maxwellian behavior was observed at low shear rates. No dichroism was detected suggesting that electrostat ic screening suppresses structure formation under shear.