Viscoelastic behavior and sol‐gel transition of cellulose/silk fibroin/1‐butyl‐3‐methylimidazolium chloride extended from dilute to concentrated solutions

The viscoelastic behavior of cellulose/silk fibroin/1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl) extended from dilute to concentrated has been studied by rheology. When the blend ratio of cellulose/silk fibroin is 8/2 (w/w), the critical overlap (c*) and entangled concentration (c e ) of the solutions are 0.5 and 2 wt% at 20°C, respectively. Moreover, the failure of Cox‐Merz at high shear rates or frequencies indicates a two‐phase structure, and the miscibility was improved with the increase of cellulose/silk fibroin concentration, as determined by the time‐temperature superposition principle and Han plot. The effect of cellulose/silk fibroin concentration on the sol‐gel transition was also studied, the gelation temperature ( T gel ) can be obtained when the concentration is in the semidilute unentangled and entangled regimes. POLYM. ENG. SCI., 58:1931–1936, 2018. © 2017 Society of Plastics Engineers