Preparation Of Regenerated Silk With High Mechanical Properties By Wet Spinning With Nano-particles Blend

Regenerated silk,as a natural polymer material,like chitosan,collagen and chitin,is nontoxic,non-irritating,degradable and has good biocompatibility.It is a common material in the field of tissue engineering.However,the mechanical properties of regenerated silk have been difficult to improve,showing low breaking strength and poor flexibility.Therefore,improving the mechanical properties of regenerated silk is of great significance for the application and development of regenerated silk.Nanomaterials are superior to common materials in mechanics due to their small size effect.Regenerated silk with enhanced mechanical properties is prepared by nano-material blending wet spinning method.The method is low in cost,environment-friendly,simple and easy to implement,and has broad industrial prospects.Firstly,the wet spinning process parameters were optimized,and the effects of different spinning solution concentrations,different stretching ratios and soaking time in ethanol on the mechanical properties of regenerated silk were studied to find out better spinning conditions.Then,copper nanoparticles(Cu NPs),copper oxide nanoparticles(CuO NPs)and copper sulfate(CuSO4)solutions were selected as blending materials to prepare regenerated silk through wet spinning method,and the effects of these three materials on the morphology,structure and mechanical properties of regenerated silk were studied.The main research results are as follows:1.In this paper,regenerated silk are prepared by wet spinning method.Taking the mechanical properties of regenerated silk as an index,the effects of different spinning solution concentrations,different stretching ratios and ethanol soaking time on the mechanical properties of regenerated silk fibroin fibers are studied.The better spinning solution concentration,the better stretching ratio and the ethanol soaking time w re found out.It provides a certain basis for the follow-up study of the effect of nanoparticles on the mechanical properties and structure of regenerated silk.2.By comparing the mechanical properties of regenerated silk prepared under different spinning solution concentrations and different stretching ratios,it is found that the spinning solution concentrations and stretching ratios have great influence on the mechanical properties of regenerated silk.When the spinning solution concentration is 15% and the stretching ratio is 3 times,the mechanical properties of regenerated silk reach the best.3.After preparing regenerated silk by wet spinning method(spinning solution concentration is 15%,stretching ratio is 3 times),the regenerated silk is soaked in ethanol for post-treatment,and the effects of different soaking times on the mechanical properties of regenerated silk are studied.The results showed that the mechanical properties of regenerated silk were not significantly changed by soaking in ethanol,indicating that the spinning speed screened by pre-experiment could meet the requirement of basically solidifying regenerated silk.4.Regenerated silk were prepared by blending different amounts of Cu NPs,CuO NPs and CuSO4 respectively.The effects of different blending ratios of Cu NPs,CuO NPs and CuSO4 on the morphology,mechanical properties and structure of regenerated silk were studied.SEM results showed that the morphology of regenerated silk was not significantly changed by blending Cu NPs,CuO NPs and CuSO4.The mechanical test results show that the mechanical properties of regenerated silk increase first and then decrease with the increase of the blending ratio of Cu NPs,CuO NPs and CuSO4.When the blending ratio of Cu NPs reaches 4 mg/g Cu NPs/SF,the prepared regenerated silk has better mechanical properties,with the breaking strength and elongation at break of 286.42 MPa and 24.70 % respectively,which are 71.56 % and 43.32 % higher than those of regenerated prepared without blending Cu NPs.When the blending ratio of copper oxide nanoparticles reaches 1mg/g CuO NPs/SF,the prepared regenerated silk has better mechanical properties,with the breaking strength and elongation at break of 241.31 MPa and 75.21 %respectively,which are 44.5% and 210.04 % higher than those of regenerated silk prepared without blending CuO NPs.When the blending ratio of CuSO4 reaches 1mg/g CuSO4/SF,the prepared regenerated silk has better mechanical properties,the breaking strength and elongation at break are 202.33 MPa and 38.58 % respectively,which are 21.19% and 59.22% higher than those of regenerated silk prepared without blending CuSO4.The results of infrared spectrum,XRD and TGA show that the main structure of regenerated silk prepared by blending Cu NPs,CuO NPs and CuSO4 has not changed compared with that of regenerated silk prepared without blending.According to infrared spectrum deconvolution technology,it is found that afterblending Cu NPs,CuO NPs and CuSO4,the secondary structure content of regenerated silk changes,showing a trend of random coil,?-helix content increasing and ?-sheet content decreasing.5.By comparing the breaking strength and elongation at break of regenerated silk prepared by blending Cu NPs,CuO NPs and CuSO4 respectively,and synthesizing the yield stress and elongation at yield,the order of their improvement on the mechanical properties of regenerated silk is as follows: Cu NPs> CuO NPs>CuSO4.The nano-particle blending method for enhancing the mechanical properties of regenerated silk is low in cost,easy to operate,green and environment-friendly,has important significance for large-scale preparation of high-performance regenerated silk fibroin fibers,and has broad industrial prospects.