Electrospinning Bombyx Mori Silk And Produce Reinforced Composite Nanofiber

Electrospinning is a simple, effective and attractive method to obtain the fibers from both natural and synthetic polymers with diameters from nanometers to micrometers. Under the high voltage, a charged jet is produced from a polymer melt or solution, and stretched in the electric field, and then the solvent evaporates and the nanofibers are solidified. As the nanofibers have several properties including three-dimensional porous structure, high surface area to volume ratio and high porosity, they can be widely used as tissue engineering scaffold and biomedical materials.In this work, the mulberry cellulose nanowhiskers (CNW) were used as the reinforcer by adding to the regenerated silk fibroin (SF) solution to prepare the nanofibers by electrospinning. Bombyx mori (B. mori) silk fibroin is a natural protein with good biocompatibility and biodegradability, oxygen and water vapor permeability, minimal inflammation. It is regarded as the ideal biomaterial, but the mechanical properties of regenerated silk fibroin fibers are inferior to the native silk fiber and spider silk, so that it is significant to improve the mechanical properties of artificial nanofibers. In this work, the effects of spinning solution concentration, voltage and distance, spinning flow rate, conductivity on the diameters and morphology of nanofibers were investigated in order to get the optimum spinning conditions. Moreover, the changes of fiber structure and properties after ethanol treatment were investigated. The results showed that with the increase of spinning solution concentration, the diameter of nanofibers was increased, but the diameter was decreased with the increase of voltage. Also the spinning distance, flow rate and conductivity would affect the diameter of nanofibers. The structure of nanofibers was markedly changed toβ-sheet conformation after the ethanol treatment. Since the CNWs have the exponent growth in Young's modulus and tensile strength compared with the cellulose and have been used as the reinforcers in the composite and electrode materials, the mulberry CNWs and the regenerated SF with different proportion were prepared to get the CNW reinforced SF composite nanofibers under the appropriate electrospinning conditions. The FE-SEM results showed that the fiber surface were smooth and the diameter of fibers decreased from ca. 250 nm to 75-160 nm with the increase of CNW content. The TEM result indicated that the CNWs were dispersed oriently in the nanofibers and distributed along the fiber axis. The tensile testing revealed that the mechanical properties of nanofibers were significantly improved after adding CNWs and the tensile strength and Young's modulus of fibers increased about 2 times when the CNW content was 2%.