Synchrotron radiation microdiffraction of natural silkworm silk and regenerated silk fibroin fibers

摘要

In order to investigate the microstructure of natural silkworm silks and regenerated silk fibroin (RSF) fibers, synchrotron radiation X-ray microdiffraction technology was applied due to limited sample amount. The RSF fibers were firstly dry-spun from RSF aqueous solution and then post-treated at different conditions. The as-spun RSF fiber exhibited strong diffraction of [201] lattice plane and weak diffraction of [020]/[200] lattice planes, while the post-treated RSF fibers showed weak diffraction of [201] lattice plane and strong diffraction of [020]/[200] lattice planes. However, the natural silk presented two main peaks of [201] and [020]/[200] lattice planes. Both diffractions were attributed to silk II structure of silk fibroin. By deconvoluting the one-dimensional wide-angle X-ray microdiffraction pattern, the crystallinity and the degree of crystalline orientation were obtained. The as-spun fiber showed low degrees of crystallinity and crystalline orientation, but the microstructure of the RSF fiber could be improved greatly and even become similar to that of the degummed natural silk by post-treatment. The effects of post-treatment method on the microstructures of the RSF fibers were also studied to obtain optimal post-treatment conditions.