Wet-Spinning of Regenerated Silk Fiber from Aqueous Silk Fibroin Solution: Discussion of Spinning Parameters

Abstract

Regenerated silk fibroin (RSF) fibers were obtained by extruding a concentrated aqueous silk fibroin solution into an ammonium sulfate coagulation bath. A custom-made simplified industrial-type wet-spinning device with continuous mechanical postdraw was used. The effect of dope concentration, coagulation bath, extrusion rate, and postdraw treatment on the morphology of RSF fiber was examined. The results showed that although RSF fiber could be formed with dope concentration between 13 and 19% (w/w), the ones spun from 15% RSF solution showed the most regular morphology being dense and homogeneous in cross-section with a smooth surface and a uniform cylindrical shape. Though it had little effect on morphology, postdraw treatment especially under steam, significantly improved the mechanical properties of the RSF fibers.

Insights into the production and characterization of electrospun fibers from regenerated silk fibroin

“…The estimated values (see above) of ultimate true stress (o-u ; MPa) and Young modulus (£; GPa) obtained after ethanol immersion of both as-spun threads (SI and S2), but especially those of S2 (266 MPa and 30 GPa for Sl-E and 404 MPa and 32 GPa for S2-E), compare well not only with the values reported in the literature for regenerated silk fibroin fibers [53,[76][77][78], but also with those of natural B. mori silk [47].…”

“…Ultimate stress (a u ) values for as-spun threads (SI and S2) range from 196 to 360 MPa, depending on the particular batch tested ( Table 2). These values are comparable with the best bio-inspired fibers [53,[76][77][78] and remarkably close to those found in degummed natural silk fibers (300-600 MPa) [47], Similar outstanding results were obtained here for the Young moduli (£, GPa) of as-spun fibers (14-20 GPa; Table 2), which resemble those of natural silk fibroin (9-17 GPa) [47] However, it should be noted that the actual densities of the threads made from aligned fibers in our study can be significantly lower than that of natural silk, due to the lower crystallinity of the electrospun fibers and the voids between them. Therefore, both the ultimate stress (a u ) and the initial elastic moduli (£, GPa) -calculated from the assumption made aboveshould be taken with caution.…”

Spider silk as a blueprint for greener materials: a review

“…The fiber so obtained can further be post-drawn, 126,196,[200][201][202][203] a treatment that is one of the favored and most efficient strategies to increase the level of molecular orientation and improve materials' mechanical response. The formation of any spidroin-based material follows essentially the same procedures than those used for the production of fibers in vitro.…”

Development of New Smart Materials and Spinning Systems Inspired by Natural Silks and Their Applications

“…This drawing process orients the silk proteins along the longitudinal axis of the fibers and improves the fibers' mechanical properties. The post-spin drawing process used by silkworms and spiders has been replicated in conventional processes to improve the mechanical properties of the artificial showed mechanical properties comparable to those of the natural silkworm silk fibers ( Figure 3C) (Zhou et al, 2009;Yan et al, 2010). The same spinning process was applied by Chen's group to a spinning dope composed of a silk fibroin-CNT composite to prepare strong artificial fibers with breaking energies comparable to that of the spider dragline silk fibers (Fang et al, 2015).…”