Extraction Of Keratin Based On Deep Eutectic Solvents And Its In-situ "One-pot" Preparation Of Easily Reconstructible Bioplastics Film Materials

In recent years,the shortage of oil resources and environmental pollution have become increasingly prominent.On the one hand,as a petroleum-derived product,the current global output of plastics is about 320 million tons per year,and the demand is rising.On the other hand,more than 300,000 tons of feather waste are generated every year in the world,and improper treatment methods have caused certain problems such as waste of resources and environmental pollution.In response to the above problems,this topic uses urea,betaine and polyols as raw materials to synthesize a series of new deep eutectic solvents(DES)for extracting chicken feather keratin.By studying the effect of the type of solvent and the addition of co-solvent on the extraction ability of keratin,the structure characteristics of the extracted keratin were characterized to reveal the mechanism of keratin dissolution.Furthermore,under the solvent system of specific chicken feather keratin extraction,by adding polyvinyl alcohol and other substances,in-situ "one-pot" polymerization is used to prepare an easy-to-rebuild bio-based plastic film,optimize the material preparation process,analyze the structure and properties of the material,and establish easy optimal preparation process of type bio-based plastic film,and realize the efficient reuse of biomass resources.The main research conclusions of this paper are as follows:(1)First,a series of alcohol DES were synthesized,including urea-1,2-propanediol,urea-1,3-propanediol,urea-ethylene glycol,urea-glycerin,betaine-ethylene glycol and betaine-1,3-propanediol and so on.At 120°C,urea-ethylene glycol has the highest solubility for feather keratin,reaching 18.06%.After adding 10% wt arginine,the solubility of feather keratin increases to 29.44%.Through structural analysis of the extracted keratin,including infrared spectroscopy(IR),X-ray crystal diffraction analysis(XRD),solid-state nuclear magnetic analysis,amino acid composition analysis,disulfide bond determination,thermogravimetric performance analysis(TGA),etc.,the extraction The keratin of keratin can basically maintain the original main structure(peptide chain).DES mainly dissolves it by destroying the disulfide bonds in the keratin structure and reducing the content of cysteine.Damaged,its secondary structure is also affected,that is,the content of ?-helix structure is reduced,and the ?-sheet and random coil structure are obviously increased,so its thermal stability is also reduced.In addition,the addition of co-solvent amino acids,especially arginine,can more damage the disulfide bonds and higher structure of chicken feather keratin through the synergistic effect of DES,resulting in a significant increase in the extraction rate of keratin.The resulting keratin heat The stability is lower.(2)Using urea-based DES for the in-situ "one-pot" construction of chicken feather keratin plastic film materials,mainly discussing the influence of solvent structure,component ratio and additives on the molding and properties of the material.In the keratin-polyvinyl alcohol binary plastic film material construction system,urea-1,2-propylene glycol has the best mechanical properties of the plastic film,the optimal DES-PVA volume ratio is 1:9,and the material tensile strength is 24.04 MPa and the stretch rate is 288.37%.On this basis,a third bio-based substance was added to construct a ternary material preparation system,and it was found that when 2 wt% sodium carboxymethyl cellulose and glucose were used as the ternary compound,the performance of the plastic film material obtained was the best(The tensile strength and elongation rate are 16.65 MPa,376.21% and 15.31 MPa,441.89% respectively).The research results show that the properties of the film can be adjusted by adding various tertiary compounds,including surface morphology,thermal stability,and hydrophobicity to meet different needs.(3)Taking the binary film material preparation system(urea-1,2-propanediol: polyvinyl alcohol;volume ratio 1:9)as the object of investigation,explore the possibility of reconstitution and the cycle of the prepared bio-based plastic film material usage.It was found that the plastic film material based on the binary system is very easy to rebuild.It can be reconstituted by dissolving it in distilled water at 90°C and drying it at 50°C.Research on the mechanical properties of the reconstructed material shows that after 2-4 cycles of reconstruction,the tensile strength remains between 17.72 MPa and 18.49 MPa,and the stretch rate can also be maintained at 287.32%-343.65%;the mechanical properties of the film are relatively stable until the first The mechanical properties of the material only declined after 5 times of reconstruction.The method of dissolving and extracting chicken feather keratin obtained by DES and the keratin dissolution mechanism disclosed in this article can help promote the effective utilization of chicken feather keratin resources,and can also enrich the relevant theoretical understanding of DES dissolving biological macromolecules.The established in-situ "one-pot method" process system for preparing keratin plastic film materials has green raw materials,simple operating procedures,easy reconstruction and recycling of film materials,and relatively stable mechanical properties,which has good application prospects.