Study On The Preparation And Mechanical Properties Of Silk Fibroin/Poly(ε-caprolactone) Blend Fibrous Scaffolds

In this thesis, silk fibroin (SF) nanofibrous membranes were prepared by electrospinning andethanol treatment. Ethanol treatment induced increasing in fiber diameters and inter-fiberconglutinating, it also leaded to predominantly β-sheet structure, and silk II crystalline structureof SF fibers. Although the tensile strength of electrospun SF fibrous membranes increasedsignificantly, while the strain decreased after ethanol treatment. Mix SF withpolycaprolactone(PCL), then SF/PCL composite nanofibrous membranes were prepared viaelectrospinning. The diameters of the composite nanofibers increased with the addition of PCL,and the mechanical properties of the composite fibers were improved effectively. So themechanical properties of composite nanofibers membrane can be adjusted by changing theamount of polymer.Aligned SF/PCL nanofibrous membranes were fabricated by electrospinning with a rotatingdrum as a collector. The morphologies of nanofibers were characterized by FE-SEM, and thedegree of orientation was evaluated by MATLAB. And the mechanical properties of electrospunnanofibers membranes were tested by uniaxial stretching machine. The results showed that theaverage diameters of nanofibers decreased with increasing the rotation speed of the drum whilethe degree of orientation was improved. Meanwhile, electrospun nanofibers membranesexhibited an anisotropic mechanical behavior, the nanofibers membranes performed a greaterbreaking stress and a less breaking strain in the drum rolling direction than these in the directionperpendicular to the rolling direction. And the higher the rolling speed was, the greater breakingstress and a less breaking strain nanofibers membranes of the drum rolling direction performed.But the nanofibers membranes showed an opposite mechanical behavior in the directionperpendicular to the rolling direction.In the biaxial tensile tests of electrospun SF/PCL nanofiberous membranes at4tensile ratesratios, which are1:1、2:1、5:1and8:1respectively, and in the cyclic biaxial tensile tests at different tensile rates ratios, which are1:1、2:1、4:1、5:1、8:1, the samples were stretched. Also,the aligned SF/PCL nanofibrous membranes were cyclically stretched at same tensile rates ratios.The results showed that the maximal stretching force of the electrospun nanofiberousmembrances was related to the tensile rates ratios, and the stretching force of the nanofiberousmembrances in the drum rolling direction was higher than in the perpendicular direction. Whilethe behavior of the samples was nonlinear and inelastic under biaxial cyclic tensile loads, theelastic power of nanofibers membrane increased with increasing the number of loading cyclesotherwise it was not affected by the tensile rates ratios, and nanofibers membrane presented alarger elastic power in the drum rolling direction than in the direction perpendicular to the rollingdirection.Now we established a force-strain mathematical model of electrospun membranes based onthe experimental curve, in order to verify and estimate the test data.