Graphene/carbon Nanotubes Enhance Regenerated Wool Keratin Fibers

The research of green and renewable biomass materials has become a hot spot in attempt to decrease the environmental pollution and waste of resources.Regenerated wool keratin fibers have some disadvantages,such as low tensile strength and poor elongation at break,which limit their further application.Herein,regenerated wool keratin/graphene oxide(GO)/amide multi walled carbon nanotubes(AMWCNTs)composite fiber and regenerated wool keratin/PEG-g-GO composite fiber were successfully fabricated with wool keratin as main raw material and GO and AMWCNTs as additives.The effects of various treatment methods on the mechanical properties of the composite fiber were fully investigated.The main contents are summarized as follows:(1)A new L-cysteine method was used to dissolve waste wool and successfully extract wool keratin.(2)The regenerated wool keratin/GO/AMWCNTs composite fibers were successfully prepared by self-made small wet spinning equipment.GO and AMWCNTs were successfully applied in this field to study their synergistic effects on regenerated wool keratin fibers.When the ratio of GO and AMWCNTs is 1:1 and the total mass of the two additions is 0.10 wt.%,the mechanical properties of the composite fibers reach the best.The tensile breaking strength and elongation at break are 145 MPa and 3.09%respectively.(3)PEG-g-GO was successfully prepared by grafting PEG400 on GO,which have good dispersibility in the spinning solution system;the regenerated wool keratin/PEG-g-GO composite fiber was successfully prepared to realize the application of PEG-g-GO to the field for the first time.When the addition of PEG-g-GO is 0.20 wt.%,the tensile rupture strength and elongation at break of the composite fiber reach their maximum,156.53 MPa and 3.91%,which increases by 168.21%and 88.89%compared with the pure regenerated keratin fiber.The tensile rupture strength of the regenerated wool keratin composite fiber reaches the maximum value reported in the previous literature.To some extent,the defects of pure regenerated keratin such as insufficient tensile breaking strength and low elongation at break have been improved.The regenerated wool keratin composite fiber was treated with hydrogen peroxide for the first time,and the effect of its concentration and treatment time on the mechanical properties of the composite fiber was studied.When treated with an aqueous solution of hydrogen peroxide for 60 min and the concentration was 10 wt.%,the tensile breaking strength of the composite fiber reached the maximum;however,when the concentration of the aqueous hydrogen peroxide solution was 15 wt.%,the elongation at break reached the maximum.(4)For the first time,glycerin was added to the coagulation bath for preparing a regenerated wool keratin composite fiber by wet spinning.The elongation at break of composite fibers has been improved due to the plasticizing effect of glycerin on biological protein materials.