Studies On Modification Of Silk Fibroin And Design Of The Related Demolding Device

In this thesis,modified silk fibroins(SF)with various PU contents were successfully prepared using one-pot method,and novel demolding device of impact testing thick sample was developed,which was especially suitable for difficult demolding of polymers like modified SF.Firstly,the structure and poperties of modified SF were investigated.Secondaly,the effects of the polyurethane prerpolymer content in the modified SF on the structure and properties of the modified SF were disclosed.Finally,the problem of demolding of silk fibroin impact testing thick sample was solved and novel demolding device was successfully developed.Meanwhile,the general applicabilities of novel demolding device were investigated.(1)We studied the structure and properties of modified SF and the effects of the polyurethane prepolymer content in the modified SF on the structure and properties of the modified SF.Polyurethane prepolymers were synthesized by polycaprolactone(PCL)tetrol and 4,4'-methylenedi-p-phenyl diisocyanate(MDI)and then mixed with silk fibroin-water mixture to prepare modified silk fibroin with various PU contents,in an environmentally friendly manner.Fourier transform infrared spectroscopy(FTIR)revealed that urethane linkages formed between SF and PUP,and the grafting ratio of PUP used for preparing modified SF was 99.1±0.2%.Polyurethane micro-particles were dispersed into SF matrix in modified SF and interacted with the SF matrix through urethane linkages,which strengthen the interface between the two phases.The special structure led to improved strength at break and elongation at break of the modified SF.In addition,compared with pure silk fibroin,the modified SF demonstrated higher strength at break,elongation at break,flexibility and hydrophobicity.These properties were also improved with the increase of PU content.Therefore,a simple and effective method to prepare high performance modified SF was successfully developed.(2)Novel demolding device was successfully developed.The success rate and general applicabilities of the demolding device for the demolding of all kinds of polymers were studied,in the experiment,based on our previous works,the design drawings of novel demolding device were draw by using of Auto CAD 2013.According to the drawings,we manufactured a kind.Then we tested the device through various polymers,the results indicated that it was suitable for demoiding all of polymers.