Rheological behavior of regenerated silk fibroin/polyvinyl alcohol blended solutions in steady and dynamic state and the effect of temperature

Abstract

Since the silk fibroin is a precious material widely used in various fields, the discarded silk textile is a profound waste in resource-constrained settings. In this paper, with recyclability in mind, we selected waste silk from discarded silk quilt to make the regenerated silk fibroin (RSF) aqueous solutions. Mixing with water-soluble polyvinyl alcohol (PVA), the RSF/PVA blended solutions were made as a spinning dope for preparing the regenerated fibers. To optimize the parameters during the spinning process, we used the rheological measurement firstly to investigate the fundamental characters of solutions with various blending ratios and the effect of temperature on solutions. The results showed the RSF/PVA blended aqueous solutions were non-Newtonian fluids, and the apparent viscosity rose with the increasing PVA contents in co-solutions and decreased with the growth of the shear rate. The blending ratio had a certain influence on the viscoelasticity of co-solutions, the more the percentage of PVA, the higher the value of the viscoelasticity of co-solutions would be, and the co-solution with blending ratio of 6:4 (RSF:PVA) showed the greatest influence on storage modulus, while the solutions with more RSF exhibited more effect on loss modulus. Too much PVA content or too high RSF proportion in solutions was unfavorable to spinning. What’s more, the co-solutions with RSF content less than 40% had the most similar morphological structural systems, and the co-solutions containing more than 20% PVA had narrow distribution, linear and high molecular weight. For preventing protein denaturation, the temperature should not be higher than around 30 °C.