Study On The Mechanism And Preparation Of Regenerated Silk Fibroin Fibers

In recent years, as people’s awareness of environmental protection and combinedwith silk resources limited, more and more attention has been paid on thedevelopment of the regenerated silk fibroin fiber. The spinning solution was based onabandoned fibroin fibers and it could get the regenerated protein fibers of goodmechanical properties by wet spinning. And the different spinning process parametersto regenerated silk protein fiber structure and performance were researched concretely,It was indicated that the regenerated silk fibroin fibers spinning process as follows:the concentration of ammonium sulfate was40%, the temperature was20℃in thecoagulation bath; the concentration of Lithium bromide, ethanol is3%and0.6%respectively, temperature20℃in the drawing bath; the hot bath stretchingtemperature of70℃; dry densification time12min, temperature of135℃;and it wouldbe successfully got the regenerated silk fibroin fibers of stretching ratio of5.16timesand the fracture strength193.60Mpa and elongation at break of15.3%under thiscondition. The fibers prepared different conditions of drying densification wereanalyzed by Scanning electron microscopy test, polarization microscope test, IRspectrum analysis, X-ray diffraction. The molecular conformation of regeneratedprotein fibers had been unchanged substantially in the drying densification of theprocess which was still α-helix and random coil structure-based, the coexistence of asmall amount of β-sheet structure. The crystallization and orientation degree ofNon-dried fibers is relatively low. however, densification, crystallinity, grain size andthe degree of orientation had greatly improved after drying,and structure of theprotein fibers was compacted and the mechanical properties was greatly improved.The evolution of the structure in the forming process was researched and it showedthat while the fibers were formed through the coagulation bath molding, drawing bathdrawing, the hot water bath stretched, dried densification, the draw ratio would be gradually increased, and the surface grooves, cracks of fibers would be graduallyreduced until smooth, and the internal voids would be gradually decreased or evendisappeared. The degree of crystallinity of the fiber had been gradually increased thedegree of orientation had been also significantly improved, but the molecularconformation of regenerated protein fibers had been unchanged substantially in thefiber forming process.