Macromolecules, Vol.30, No.18, 5372-5375, 1997
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 samples were found to be birefringent under flow, with the steady state birefringence having a concentration scaling of c(3.9). This scaling behavior suggests a wormlike conformation of the silk molecules in solution. The relaxation was fast, and Maxwellian behavior was observed at low shear rates. No dichroism was detected suggesting that electrostatic screening suppresses structure formation under shear.