Effect of Spinning Conditions and Dope Composition on DrySpun Coaxial Fibers from Regenerated Silk FibroinSericin Aqueous Solution

To biomimic the spinning process of silkworm, the composition and the coreshell structure of natural Bombyx mori silk, regenerated silk fibroinsericin (RSF-SS) fibers with a core (RSF)shell (SS) structure were prepared using coaxial dryspinning process. The effect of takeup rate and mass fraction of RSF in core dope on the morphology, the secondary structure and the mechanical properties of the fibers were investigated. Results showed that the RSF-SS composite fibers had coreshell structures. Compared to the mass fraction of RSF in core dope, the takeup rate significantly affected the secondary structure and the mechanical properties of the coaxial dryspun RSF-SS fibers. The diameters decreased and the content of βsheet conformation of the coaxial fibers increased when the takeup rate increased from 1 cm/s to 5 cm/s. The fibers with the best mechanical properties were obtained at a takeup rate of 3 cm/s. The decreasing of the mass fraction of RSF in core dope resulted in a diameter decrease of the coaxial fiber, and increase of the content of βsheet conformation and the breaking stress of the fibers. However, the initial modulus, the breaking strain and the breaking energy of the fibers only decreased slightly.