Dissolution And Regeneration Of Wool In NMMO Solution And Preparation Of Its Composites Film With Cellulose

In modern society,non-renewable resources such as coal and petroleum are increasingly in short supply,and their production causes pollution.Considering the sustainability of petroleum resources and the environmental problems caused by the refractory degradation of petroleumbased materials,renewable bio-based materials have become a research hotspot in today’s society..Every year,the breeding and wool spinning industry in my country produces a large amount of discarded wool scraps during the processing.The main component of wool is wool keratin,which is a very considerable keratin resource.At present,the industrialization of keratin application is relatively slow,and most applications are still in the laboratory stage.Most of the waste keratin is incinerated or landfilled.A small part of the waste keratin is regenerated by physical methods,and the molecular weight of the regenerated keratin is low（less than 5k Da）.),usually used as animal feed additives,with low application value.Therefore,the waste keratin is prepared as a regenerated material to realize industrial application,and resource reuse can be realized.This paper studies a new method for the recycling of waste wool.NMMO is a green and recyclable solvent,which has been used in the industrial production of Lyocell fiber as a solvent to extract regenerated keratin.In view of the problem of poor mechanical properties of pure keratin materials,the mechanical properties of regenerated keratin are improved by compounding with natural macromolecular cellulose and cross-linking modification.Firstly,the green solvent NMMO was used as solvent to extract keratin from waste wool,and the dissolution of wool in NMMO was studied by polarized light microscope,and the structure of keratin before and after regeneration was studied by FT-IR,XRD,TGA,SDS-PAGE gel electrophoresis,etc.performance changes.The study found that The NMMO moisture content decreases and the dissolution temperature increases,resulting in an increase in the dissolved mass fraction of wool and a deepening of the solution color.Under the condition of 85℃,using NMMO solution with a moisture content of 15% to dissolve wool,the dissolved mass fraction of wool reaches 7.5%,and the color of the solution is lighter,and the extraction rate of regenerated keratin can reach 60%.The molecular weight of regenerated keratin decreases,but retains the molecular structure of protokeratin.The molecular weight of regenerated keratin ranges from 25 to 200 kda Compared with the original wool,Partial α-helix structure converted to β-sheet structure,and the relative crystallinity decreased.Secondly,because pure keratin powder cannot form a film,and its application is limited,NMMO is used as a co-solvent to dissolve cellulose and wool respectively to prepare cellulose/keratin composite films with different keratin and keratin contents.The properties of cellulose film and composite film were tested and characterized by SEM,FT-IR,XRD,TGA and universal stretching machine.It was found that with more and more keratin in the composite film,its mechanical properties became worse,its thermal stability became better,and its crystallinity became worse.When the keratin content of the film material is 25%,the crystallinity is the best,the breaking strength is 58.5MPa,the elongation at break is 4.8%,and the mechanical properties are the best.When the keratin content continued to increase to 50%,the crystallinity decreased,and the agglomeration of keratin particles caused the breaking strength and elongation at break to decreased sharply to 30.3 MPa and 3%.Finally,in order to enhance the Breaking strength of the materials,three cross-linking agents:glutaraldehyde,ethylene glycol diglycidyl ether（EGDE）,and genipin were used to modify the composite membrane.The properties of cellulose film and composite film were tested and characterized by SEM,FT-IR,XRD,TGA and universal stretching machine.The thermal stability,crystallinity and Breaking strength of the modified composite films were improved.The crosslinking effect of EGDE,glutaraldehyde and genipin was better when the dosage of cross-linking agent was 15wt%,15wt% and 1.5wt%,of which 15wt% EGDE had the best cross-linking effect.The breaking strength of the protein composite membrane reached 38 MPa,which was 27.8%higher than that of the cellulose/keratin membrane.