| Keratin is a kind of natural and renewable resource with good biocompatibility and has important applications in biomedical and engineering materials.However,the preparation of the keratin solution presents great problems.Natural keratin is difficult to dissolve,extract and concentrate,which is ascribed to the keratin molecules are hydrophobic and have a large number of sulfhydryl/disulfide bonds.During the process of concentration,keratin molecules tend to agglomerate or cross-link,and eventually flocculate and precipitate.Therefore,it is necessary to modify the keratin molecule to improve its stability and subsequently prepare the regenerative keratin material with good performance.In this paper,the eutectic system was used as a solvent to dissolve and modify wool keratin by one-bath method.The stability of wool keratin was greatly improved by PEG modification,and its concentrated solution was prepared.The wet spinning characteristics of concentrated solution and the application of modified keratin in coating finishing were studied.Firstly,keratin was dissolved by reductive eutectic system,and then PEGylated by polyethylene glycol dimethacrylate.The PEG modified keratin solution was tested and analyzed by UV spectrophotometer,fluorescence spectrometer,particle size and potential analyzer and circular dichroism chromatograph to explore the influence of PEG modified keratin solution on the stability.The results showed that PEG modified keratin can effectively stretch the molecular chain of keratin,reduce the content of free sulfhydryl groups,narrow the particle size distribution range,promote the secondary conformation of keratin from ?-helix to?-sheet,and enhance the stability of keratin in aqueous solution.After that,the modified keratin solution was concentrated,and its concentration could exceed 300 g/L.The concentrated solution properties of modified keratin were tested by Raman spectrometer,polarizing microscope and rotary rheometer.The results showed that the higher the concentration of modified keratin,the greater the proportion of ?-sheet structure in the solution;the keratin solution with high concentration was very sensitive to shear force,and molecular chain orientation behavior occurred under shear force,resulting in anisotropy of concentrated solution system,which laid a foundation for the preparation of regenerated fibers.Secondly,PEG-g-Ker and sodium alginate were blended to prepare regenerated keratin fibers by wet spinning.Scanning electron microscopy showed that the surface of fiber was smooth and there was no wool scale layer structure and natural crimp.Mechanical tests showed that the mechanical properties of keratin fibers were similar to that of natural wool.When the blending ratio of modified keratin and sodium alginate was 2 :1,the breaking strength and elongation at break were 4.89±0.98 c N/tex and 21.70±5.16%,respectively.XRD results showed that the crystallinity of the regenerated keratin fibers was more than 30%,and ?-sheet crystals were mainly found.DSC and TGA tests showed that the thermal stability of regenerated keratin fibers was not as good as that of natural wool.Regenerated keratin fibers have high water solubility and have potential as water-soluble special application materials.Finally,the application of PEG modified keratin in fabric finishing was studied.After blending PEG modified keratin with waterborne polyurethane,the wool fabric was treated with a hydrophilic coating and its wear-ability was tested.The results showed that the PEG modified keratin/waterborne polyurethane coating can form uniform film on the fiber surface,and significantly improve the hydrophilicity,felting properties and anti-pilling properties of the fabric.After finishing,the fabric can be completely wetted in 3 s,the felt shrinkage rate was reduced to less than 2%,and the anti-pilling grade was 3(1500 times friction),but the overall feel of the fabric was slightly hard. |
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