Post-spin Stretch Improves Mechanical Properties, Reduces Necking, and Reverts Effects of Aging in Biomimetic...

Recent biotechnological advancements in protein production and development of biomimetic spinning procedures make artificial spider silk a promising alternative to petroleum-based fibers. To enhance the competitiveness of artificial silk in terms of mechanical properties, refining the spinning techniques is imperative. One potential strategy involves the integration of post-spin stretching, known to improve fiber strength and stiffness while potentially offering additional advantages. Here, we demonstrate that post-spin stretching not only enhances the mechanical properties of artificial silk fibers but also restores a higher and more uniform alignment of the protein chains, leading to a higher fiber toughness. Additionally, fiber properties may be reduced by processes, such as aging, that cause increased network entropy. Post-spin stretching was found to partially restore the initial properties of fibers exposed aging. Finally, we propose to use the degree of necking as a simple measure of fiber quality in the development of spinning procedures for biobased fibers.