Glutamic acid esterified cellulose, composite fiber and preparation method and application thereof

Abstract

The invention provides glutamic acid esterified cellulose, a composite fiber and a preparation method and application thereof, and relates to the technical field of composite fiber preparation. According to the preparation method, glutamic acid esterified cellulose is prepared firstly, then the glutamic acid esterified cellulose, keratin and cellulose are used together to prepare the composite cellulose, and the glutamic acid esterified cellulose can be used as an emulsifier in the process, so that the compatibility between the keratin and the cellulose is improved, and the keratin and the cellulose can be combined together; the characteristics of high toughness of the keratin fiber and high strength of the cellulose are greatly utilized, and finally the composite fiber with high strength and high toughness is prepared; secondly, by regulating and controlling the modification degree of the cellulose in the preparation process of the glutamic acid esterified cellulose and the adding amount of the glutamic acid esterified cellulose, precise regulation and control of the performance of the composite fiber are achieved, and it is ensured that the composite fiber with the excellent performance is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of composite fiber preparation, and in particular to glutamic acid esterified cellulose, composite fiber and a preparation method and application thereof. Background Art

[0002] In recent years, with the increasing awareness of sustainable development in society, recycling waste textiles to produce regenerated fibers has become a research hotspot in the field of chemical fibers. Among them, waste wool textiles are ideal raw materials for recycling proteins to prepare regenerated fibers due to their high keratin content. As the most promising type of green solvent, ionic liquids have been widely used in the field of recycling waste wool textiles (Journal of Molecular Liquids, 2022, 350, 118595). However, wool keratin has a low relative molecular mass (10-50KDa), and the regenerated keratin fibers have poor mechanical strength and cannot be used in practice. One way to overcome these limitations is to blend and spin with high molecular weight biopolymers such as cellulose to change its rheological properties, thereby improving spinnability and fiber strength. The cellulose in waste cotton fabrics has a large molecular weight and high content, and can be directly dissolved in ionic liquids as a cellulose raw material after crushing. However, due to the poor compatibility between keratin and cellulose, the mechanical properties of the directly blended materials are poor.

[0003] In view of this, it is necessary to design an improved glutamic acid esterified cellulose, composite fiber and preparation method and application thereof to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a glutamic acid esterified cellulose, a composite fiber and a preparation method and application thereof.

[0005] To achieve the above-mentioned object of the invention, the present invention provides a method for preparing glutamate-esterified cellulose, comprising the following steps:

[0006] The powdered cellulose is dissolved in an ionic liquid, and N-phthaloyl-L-glutamic anhydride, dimethylacetamide and 4-dimethylaminopyridine are added, and heated and stirred at 70-80°C for 2-3 hours. After the stirring is completed, the solution is poured into an anhydrous ethanol coagulation bath until the anhydrous ethanol is transparent, and the grafted anhydride product is collected by filtration; the grafted anhydride product is added to dimethyl sulfoxide, the pH value of the solution is adjusted to 9-10, and after stirring at 80-100°C for a certain period of time, the glutamic acid esterified cellulose is obtained by washing and drying.

[0007] Preferably, the ionic liquid is 1-ethyl-3-methylimidazolium acetate, the addition amount of which is 3-6 g, and the mass fraction of the powdered cellulose in the ionic liquid is 2-3%.

[0008] Preferably, the mass of the N-phthaloyl-L-glutamic anhydride is 5-20 times the mass of the powdered cellulose, the added amount of the dimethylacetamide is 2-4 g, and the added amount of the 4-dimethylaminopyridine is 0.5 times the mass of the powdered cellulose.

[0009] Furthermore, the present invention also provides a method for preparing composite fibers by esterifying cellulose with glutamic acid, comprising the following steps:

[0010] Preparation of keratin powder;

[0011] Preparation of composite fiber: Keratin powder, glutamic acid esterified cellulose and cellulose are dissolved in a mixed solution of ionic liquid and DMSO to prepare wool keratin / cellulose composite fiber spinning solution; the composite fiber is prepared by wet spinning method with water as coagulation bath.

[0012] Preferably, the mass ratio of the keratin powder to the cellulose is 1:1, the mass fraction of the cellulose in the mixed solution is 2-3.5%, the mass fraction of the keratin powder in the mixed solution is 2-3.5%, and the mass of the glutamate esterified cellulose is 1-15% of the mass of the keratin powder.

[0013] Preferably, the keratin powder is prepared by the following method: degreasing raw wool with a sodium bicarbonate aqueous solution, and then drying to obtain pretreated wool; immersing the pretreated wool in a treatment solution, stirring at 80-100° C. for 4-6 hours, centrifuging, and dialyzing the upper solution to obtain a keratin solution; 2 SO 4 A mixed solution of HCl is added to the keratin solution, stirred for 3-5 minutes, and the obtained precipitate is dried to obtain the keratin powder.

[0014] Preferably, the treatment liquid is prepared from urea, sodium dodecyl sulfate, L-cysteine ​​and water, and its pH is 10-11; the molar concentration of urea in the treatment liquid is 6-8 mol / L, the molar concentration of sodium dodecyl sulfate is 0.01-0.02 mol / L, the mass of L-cysteine ​​is 10% of the weight of the wool, and the mass of the wool is 3-5 g.

[0015] Preferably, the ionic liquid is 1-ethyl-3-methylimidazolium acetate, the amount of which is added is 1-2 g, and the amount of DMSO added is 4-8 g.

[0016] Preferably, the Na 2 SO 4 and HCl mixed solution 2 SO 4The molar concentration of is 1 mol / L, and the molar concentration of HCl is 1 mol / L.

[0017] In particular, the composite fiber prepared by the above preparation method can be used to prepare functional textiles.

[0018] The beneficial effects of the present invention are:

[0019] 1. The preparation method of glutamate-esterified cellulose provided by the present invention effectively improves the amphiphilicity of cellulose by modifying cellulose with glutamate. The cellulose with such characteristics can be used as an emulsifier in the process of combining keratin and cellulose.

[0020] 2. The preparation method of the composite fiber provided by the present invention uses glutamic acid esterified cellulose, keratin and cellulose as raw materials, and glutamic acid esterified cellulose is used as an emulsifier. In the above process, by adjusting the amount of glutamic acid esterified cellulose added, the compatibility of keratin and cellulose can be increased while ensuring that the spinning solution system remains stable, avoiding the aggregation of glutamic acid esterified cellulose to form lumps, resulting in defects in the fiber, and further affecting the overall structure and mechanical properties of the fiber. Through the above technical solution, the problem of poor compatibility between keratin and cellulose and poor performance of the composite fiber in the prior art when preparing composite 70-fibers is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The diagram is a mechanism diagram for preparing glutamate-esterified cellulose according to the present invention;

[0022] Figure 2 This is a production process flow chart of extracting wool keratin according to the present invention;

[0023] Figure 3 This is an optical photograph of the composite fiber prepared in Example 2 of the present invention;

[0024] Figure 4 for Figure 3 SEM image of the composite fiber after knotting;

[0025] Figure 5 This is a state diagram of using the composite fiber prepared in Example 2 of the present invention to hang a heavy object; DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0028] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0029] On the one hand, see Figure 1 As shown, the present invention provides a method for preparing glutamate esterified cellulose, comprising the following steps:

[0030] After dissolving powdered cellulose in an ionic liquid, adding a predetermined amount of N-phthaloyl-L-glutamic anhydride, dimethylacetamide (DMAC) and 4-dimethylaminopyridine (DMAP), heating and stirring at 70-80° C. for 2-3 hours, after the stirring is completed, pouring the solution into an anhydrous ethanol coagulation bath for regeneration until the anhydrous ethanol is transparent, filtering and collecting the grafted anhydride product; adding the above grafted anhydride product to dimethyl sulfoxide (DMSO), and adding 20% ​​KOH solution to adjust the solution pH to 9-10, stirring at 80-100° C. for a certain period of time, thoroughly washing with deionized water, then collecting by filtering, and finally drying in a blast furnace for 1 hour to obtain glutamic acid esterified cellulose.

[0031] In the above technical scheme, by modifying cellulose with N-phthaloyl-L-glutamic anhydride, the obtained glutamic acid esterified cellulose has amphiphilicity (hydrophilicity and lipophilicity) and can be used as an emulsifier. In particular, the glutamic acid esterified cellulose proposed in the present invention has both hydrophilic groups (such as carboxyl groups and amino groups) and hydrophobic groups (ester groups) in the molecular structure. This amphiphilic structure enables it to effectively establish an interface between materials of different polarities and enhance the compatibility between different components. Therefore, it is particularly suitable for materials with large polarity differences such as cellulose and keratin. Secondly, the esterified group can form a relatively stable interface film, which helps to improve the mechanical properties of the blended fiber (such as tensile strength and toughness), and can effectively control the dispersion state of the fiber and keratin to avoid undesirable phase separation.

[0032] As an embodiment of the present invention, the ionic liquid is 1-ethyl-3-methylimidazolium acetate, the amount of the ionic liquid added is 3-6g, the mass fraction of powdered cellulose in the ionic liquid is 2-3%, the mass of N-phthaloyl-L-glutamic anhydride is 5-20 times the mass of powdered cellulose, the amount of dimethylacetamide added is 2-4g, and the amount of 4-dimethylaminopyridine added is 0.5 times the mass of powdered cellulose. By regulating the amount of N-phthaloyl-L-glutamic anhydride added, the amount of other raw materials added and the experimental conditions, glutamic acid esterified cellulose that can be used as an emulsifier in the preparation process of keratin / cellulose composite fibers is obtained.

[0033] As an embodiment of the present invention, the stirring speed after adding N-phthaloyl-L-glutamic anhydride, dimethylacetamide and 4-dimethylaminopyridine is 800-1500 rpm.

[0034] As an embodiment of the present invention, after adding the grafted anhydride product to dimethyl sulfoxide, the stirring speed is 800-1500 rpm and the stirring time is 1-2 hours; in this step, the amount of dimethyl sulfoxide added is 15 times the mass of cellulose.

[0035] In another aspect, the present invention provides a method for preparing composite fibers using the above-mentioned glutamic acid esterified cellulose, comprising the following steps:

[0036] Preparation of keratin powder: After degreasing the raw wool with sodium bicarbonate aqueous solution, washing with deionized water and drying for 12 hours, the pretreated wool is obtained; the pretreated wool is immersed in the treatment solution, stirred at 80-100°C for 4-6 hours, the mixed solution is centrifuged, the upper solution is collected, and urea and small molecular peptides are removed by dialysis to obtain a keratin solution; under stirring, the Na 2 SO 4 A mixed solution of HCl and HCl is added to the keratin solution and stirred for 3-5 minutes to reduce the pH of the solution to below the isoelectric point of keratin until a white flocculent precipitate appears in the keratin solution, and the precipitate is collected by filtration and thoroughly washed with deionized water. The keratin is further freeze-dried, crushed and stored at low temperature for further use. The specific preparation process is as follows: Figure 2 As shown;

[0037] Preparation of composite fiber: keratin powder, glutamic acid esterified cellulose and cellulose are dissolved in a mixture of ionic liquid and DMSO, stirred at 80-100°C for 1-2 hours, and centrifuged to obtain a wool keratin / cellulose composite fiber spinning solution; the spinning solution is injected into a syringe, and a wet spinning method is adopted with water as a coagulation bath to obtain a composite fiber.

[0038] In particular, the composite fiber prepared by the preparation method proposed in the present invention has the performance characteristics of high strength and high toughness, and can be applied to fields such as high-performance textiles (such as clothing, sportswear, functional textiles, etc.) with high performance requirements.

[0039] In the above technical scheme, by using glutamate-esterified cellulose as an emulsifier to prepare composite fibers together with keratin powder and cellulose, the emulsifier glutamate-esterified cellulose can be used to improve the compatibility of keratin and cellulose, so that the two can be better combined together, thereby improving the stability of the composite fibers. This is because: the amino and carboxyl groups in the glutamic acid group are polar and can form hydrogen bonds and electrostatic interactions with the polar amino acid residues in keratin. Secondly, the hydrophobic part of the glutamate-esterified cellulose can help dissolve the hydrophobic structure in keratin or disperse keratin powder, thereby improving the dispersibility of keratin. At the same time, the glutamate-esterified cellulose can form an interface film between cellulose and keratin to reduce the interfacial tension between cellulose and keratin, thereby enabling the two to be better mixed. On the other hand, glutamic acid esterified cellulose can improve the compatibility between keratin and cellulose, and give full play to the low strength and high toughness of keratin fibers and the high strength and low toughness of cellulose fibers. At the same time, glutamic acid esterified cellulose can also form a certain cross-linking effect between cellulose and keratin through reaction or adsorption with keratin, further improving the mechanical properties (such as strength and toughness) of the composite fiber. Under the above effect, it is ensured that the composite fiber with excellent mechanical properties is obtained. In particular, glutamic acid esterified cellulose forms a cross-linking structure with keratin through its polar groups, which is likely to improve the hygroscopicity and air permeability of the composite fiber, giving the composite fiber a variety of excellent properties.

[0040] As an embodiment of the present invention, the molar concentration of the sodium bicarbonate aqueous solution is 0.2 mol / L, the degreasing treatment time is 2-4 hours, the drying temperature is 25-40°C; and the weight ratio of wool to the sodium bicarbonate aqueous solution is 1:20.

[0041] As an embodiment of the present invention, the treatment liquid is prepared by urea, sodium dodecyl sulfate, L-cysteine ​​and water, the pH is 10-11, the molar concentration of urea is 6-8 mol / L, the molar concentration of sodium dodecyl sulfate is 0.01-0.02 mol / L, the mass of L-cysteine ​​is 10% of the weight of the wool after pretreatment, and the mass of the wool is 3-5g; the stirring speed after adding the wool to the treatment liquid is 800-1500rpm. The pH of the treatment liquid can be regulated by adding 5 mol / L NaOH solution.

[0042] As an embodiment of the present invention, the centrifugal conditions of the wool after being treated with the treatment liquid are: centrifugal time 10-15min, rotation speed 7000-8000rpm.

[0043] As an embodiment of the present invention, the dialysis treatment time does not exceed 3 days, and the molecular weight cutoff of the dialysis bag is 3000-3500.

[0044] As an embodiment of the present invention, Na 2 SO 4 Na in a mixed solution of HCl 2 SO 4 The molar concentration of is 1 mol / L, the molar concentration of HCl is 1 mol / L; the isoelectric point pH is less than 4.5.

[0045] As an embodiment of the present invention, the freeze-drying time does not exceed 24 hours, and the low temperature is 0-5°C.

[0046] As an embodiment of the present invention, the mass fraction of cellulose in the mixed solution of ionic liquid and DMSO is 2-3.5%, the ionic liquid is 1-ethyl-3-methylimidazolium acetate, the amount of which is 1-2g, and the amount of DMSO added is 4-8g; the mass ratio of keratin powder and cellulose is 1:1, the mass fraction of cellulose in the mixed solution is 2-3.5%, the mass fraction of keratin powder in the mixed solution is 2-3.5%, and the mass of glutamic acid esterified cellulose is 1-15% of the mass of keratin powder; the stirring speed in this step is 800-1500rpm, the centrifugation time is 3-5min, and the centrifugation speed is 7000-8000rpm. It should be noted that the cellulose used in this scheme is obtained by processing fiber plants, and the processing method is a commonly used method in the art, so it is not repeated here.

[0047] As an embodiment of the present invention, the spinning temperature is 25-40° C., and the syringe perfusion flow rate is not less than 0.1 mL / m.

[0048] The following is a further description of the glutamic acid esterified cellulose, composite fiber, preparation method and application thereof proposed by the present invention in conjunction with specific embodiments:

[0049] Example 1

[0050] This embodiment prepares a glutamate esterified cellulose, comprising the following steps:

[0051] 1.5 g of cellulose powder was added to a mixed solution of 1-ethyl-3-methylimidazolium acetate ionic liquid (30 g) and DMAC (20 g), and then 22.5 g of N-phthaloyl-L-glutamic anhydride and 0.75 g of DMAP were added, and the mixture was stirred at 80° C. and 800 rpm for 1 h. The dissolved solution was poured into an anhydrous ethanol coagulation bath for regeneration, and the anhydrous ethanol was replaced several times during the process until the solution was transparent. Then, the grafted anhydride product was collected by filtration, and the grafted anhydride product was further dried at 60° C. for 1 h. 1 g of the grafted anhydride product was added to 15 g of dimethyl sulfoxide, and the pH of the solution was adjusted to 9.5 using a 20% by mass KOH solution, heated at 80° C. and stirred at 800 rpm for 1 h, and thoroughly washed with deionized water, and then collected by filtration, and finally dried at 60° C. for 1 h to obtain glutamic acid esterified cellulose.

[0052] Example 2

[0053] This embodiment prepares a high-strength regenerated wool keratin / cellulose composite fiber, comprising the following steps:

[0054] The raw wool was immersed in 500 mL of 0.2 mol / L sodium bicarbonate aqueous solution for 2 h to degrease the wool; after treatment, it was washed with deionized water and dried at 35°C for 12 h to obtain pretreated wool; 5 g of the pretreated wool was cut and added to 100 mL of the treatment solution, 5 mol / L NaOH solution was added dropwise to adjust the pH to 10.6, and magnetic stirring was performed at 90°C for 4 h at a stirring speed of 800 rpm; the solution obtained after dissolution was centrifuged at a speed of 8000 rpm for 15 min, the upper clear green solution was collected to remove the wool residue, and dialyzed with deionized water (3500 Da cellulose dialysis bag) at 25°C for 3 days to remove urea and small molecular peptides to obtain a keratin solution, and 1 mol / L NaOH was added under constant stirring. 2 SO 4 and HCl are added dropwise to the keratin solution to reduce the pH value of the solution to below 4.5, until a white flocculent precipitate appears in the keratin solution, the precipitate is collected by filtration, and thoroughly washed with deionized water, the keratin is further freeze-dried for 24 hours, crushed, and sealed and stored at 5°C for further use; wherein the weight ratio of wool to sodium bicarbonate aqueous solution is 1:20, the treatment solution is prepared by urea, SDS, L-cysteine ​​and water, wherein the concentration of urea is 8 mol / L, the concentration of SDS is 0.02 mol / L SDS, the amount of which is added is 100 mL, and the amount of L-cysteine ​​added is 10% of the weight of the wool;

[0055] 0.182 g of keratin powder, 0.002 g of glutamic acid esterified cellulose obtained in Example 1, 0.182 g of cotton pulp, 1 g of 1-ethyl-3-methylimidazole acetate ionic liquid and 4 g of DMSO were mixed, stirred at 80°C at a speed of 800 rpm for 2 h, and finally centrifuged to prepare a transparent and viscous regenerated wool keratin / cellulose composite fiber spinning solution; the spinning solution was transferred to a syringe and extruded into a coagulation bath through a 21G needle at an extrusion rate of 0.1 mL / h, and the wool keratin / cellulose composite fiber was obtained by washing and drying.

[0056] The optical photograph of the composite fiber prepared in this embodiment is as follows: Figure 3 As shown, the SEM image of the composite fiber in the knotted state is as follows Figure 4 As shown in FIG. 1 , the results show that the composite fiber prepared by the preparation method proposed in this embodiment has high flexibility; the composite fiber (with a diameter of 140 μm) is used to hang a weight (here a 350 g weight is used as the weight), and the state of the composite fiber during the hanging process is shown in FIG. Figure 5 As shown, the results show that the composite fibers have excellent mechanical properties.

[0057] Examples 3 to 7

[0058] The difference between Examples 3 to 7 and Example 1 is that when preparing the spinning solution, the amount of glutamic acid esterified cellulose added is different from that in Example 2, and the other experimental parameters and experimental steps are the same as those in Example 2, which will not be repeated here. The comparison of the amount of glutamic acid esterified cellulose added in Examples 2 to 7 and the mechanical properties of the composite fibers prepared under the corresponding conditions is shown in Table 1. From the data in the table, it can be seen that with the increase in the amount of glutamic acid esterified cellulose added, the mechanical properties of the composite fibers show a trend of first increasing and then decreasing, and when the amount of glutamic acid esterified cellulose added is 5%, the mechanical properties of the composite fibers are the best. The reason for the above phenomenon may be that when the amount of glutamic acid esterified cellulose added is too much, the glutamic acid esterified cellulose will aggregate and form lumps, resulting in defects in the fibers. These aggregates may become stress concentration points, thereby reducing the strength of the material and affecting the overall mechanical properties of the fibers.

[0059] The above mechanical properties were obtained using a 5943 universal material testing machine from INSTRON, USA. Before the test, the composite fiber was allowed to equilibrate for 12 hours at a temperature of 23°C and a humidity of 65%. During the test, the sample was stretched at a speed of 20 mm / min and the test length was 20 mm, i.e., under pre-tension, the length of the fiber sample was 20 mm.

[0060] Table 1 Addition amount of glutamic acid esterified cellulose in Examples 2 to 7 and mechanical properties of composite fibers obtained under corresponding conditions

[0061]

[0062] Examples 8 to 10

[0063] The only difference between Examples 8 to 10 and Example 4 is that during the preparation of glutamate-esterified cellulose, the amount of N-phthaloyl-L-glutamic anhydride added is different from that in Example 4. Other experimental parameters and experimental steps are the same as those in Example 4 and will not be repeated here. The comparison of the amount of N-phthaloyl-L-glutamic anhydride added in Example 4 and Examples 8 to 10 (this amount represents the multiple of its amount added relative to the mass of cellulose) and the properties of the composite fibers obtained under the corresponding conditions is shown in Table 2. It can be seen from the data in the table that when the amount of N-phthaloyl-L-glutamic anhydride added is too large, the performance of the composite fiber obtained is poor. This is because: the addition of N-phthaloyl-L-glutamic anhydride can modify cellulose. When its addition amount is too large, it will lead to excessive modification of cellulose, causing too many emulsifier molecules to gather at the contact interface between cellulose and keratin, making the spinning solution system unstable, and the internal structure of the obtained composite fiber is uneven, affecting the overall structure and mechanical properties of the fiber; secondly, too many glutamate groups may form an unstable interface structure, which impairs the toughness and strength of the composite fiber.

[0064] Table 2 The amount of N-phthaloyl-L-glutamic anhydride added in Examples 4 and 8 to 10 and the properties of the composite fibers obtained under the corresponding conditions

[0065]

[0066]

[0067] Comparative Example 1

[0068] The difference between Comparative Example 1 and Example 4 is that glutamic acid esterified cellulose is not added, but keratin powder and cotton pulp are directly used to prepare the composite fiber, and the preparation method thereof comprises the following steps:

[0069] The raw wool was immersed in a sodium bicarbonate aqueous solution with a concentration of 0.2 mol / L for 2 hours to degrease the wool; after treatment, it was washed with deionized water and dried at 35°C for 12 hours to obtain pretreated wool; 5 g of the pretreated wool was cut and added to 100 mL of the treatment solution, 5 mol / L NaOH solution was added dropwise to adjust the pH to 10.6, and magnetic stirring was performed at 90°C for 4 hours at a stirring speed of 800 rpm; the solution obtained after dissolution was centrifuged at a speed of 8000 rpm for 15 minutes, the upper clear green solution was collected to remove the wool residue, and dialyzed with deionized water at 25°C (3500Da cellulose dialyzate) bag) for 3 days to remove urea and small molecule peptides to obtain a keratin solution, under constant stirring, a mixed solution of 1 mol / L Na2SO4 and HCl is added dropwise to the keratin solution to reduce the pH of the solution to below 4.5, until a white flocculent precipitate appears in the keratin solution, the precipitate is collected by filtration, and thoroughly washed with deionized water, the keratin is further freeze-dried for 24 hours, crushed, and sealed and stored at 5°C for further use; wherein the weight ratio of wool to sodium bicarbonate aqueous solution is 1:20, and the treatment solution is prepared by urea, SDS, L-cysteine ​​and water, wherein the concentration of urea is 8 mol / L, the concentration of SDS is 0.02 mol / L SDS, and the amount of L-cysteine ​​added is 10% of the weight of the wool;

[0070] 0.182 g of keratin powder and 0.182 g of cotton pulp prepared in the above steps were dissolved in 1 g of 1-ethyl-3-methylimidazole acetate ionic liquid and 4 g of DMSO, stirred at 80°C and 800 rpm for 2 h, and finally centrifuged to prepare a transparent and viscous wool keratin / cellulose composite fiber spinning solution; the spinning solution was transferred to a syringe and extruded into a coagulation bath (deionized water) through a 21G needle at an extrusion rate of 0.1 mL / h, and the wool keratin / cellulose composite fiber was obtained after washing and drying.

[0071] The performance comparison of the composite fibers obtained in Comparative Example 1 and Example 4 is shown in Table 3. From the data in the table, it can be seen that after adding glutamate esterified cellulose, the tensile strength of the composite fiber increases from 102.85 MPa in Comparative Example 1 to 146.15 MPa in Example 4, an increase of 42.1%. It may be that glutamate esterified cellulose forms a good interface bonding, effectively enhances the interaction between the fibers, and increases the strength and toughness of the composite fiber; in addition, the emulsification effect of glutamate esterified cellulose not only improves the compatibility, but also may affect the uniformity of the fiber structure, reducing the problem of structural unevenness caused by poor compatibility, thereby improving the quality and mechanical properties of the composite fiber.

[0072] Table 3 Properties of composite fibers obtained in Comparative Example 1 and Example 4

[0073] project Fracture stress (MPa) Fracture strain (%) Example 4 146.15 30.52 Comparative Example 1 102.85 20.41

[0074] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing glutamic acid esterified cellulose, characterized in that: The steps include: Dissolve powdered cellulose in ionic liquid, add N-phthaloyl-L-glutamic anhydride, dimethylacetamide and 4-dimethylaminopyridine, and heat and stir at 70-80°C for 2-3h. After stirring, pour the solution into an anhydrous ethanol coagulation bath until the anhydrous ethanol becomes transparent, and collect the grafted anhydride product by filtration; The grafted anhydride product is added into dimethyl sulfoxide, the pH value of the solution is adjusted to 9-10, and after stirring at 80-100° C. for a certain period of time, the glutamic acid esterified cellulose is obtained through washing and drying.

2. The preparation method according to claim 1, characterized in that: The ionic liquid is 1-ethyl-3-methylimidazolium acetate, the addition amount of which is 3-6 g, and the mass fraction of the powdered cellulose in the ionic liquid is 2-3%.

3. The preparation method according to claim 1, characterized in that: The mass of the N-phthaloyl-L-glutamic anhydride is 5-20 times the mass of the powdered cellulose, the added amount of the dimethylacetamide is 2-4 g, and the added amount of the 4-dimethylaminopyridine is 0.5 times the mass of the powdered cellulose.

4. A method for preparing composite fibers using glutamic acid esterified cellulose obtained by the preparation method according to any one of claims 1 to 3, characterized in that: The steps include: Preparation of keratin powder; Preparation of composite fiber: Keratin powder, glutamic acid esterified cellulose and cellulose are dissolved in a mixed solution of ionic liquid and DMSO to prepare wool keratin / cellulose composite fiber spinning solution; the composite fiber is prepared by wet spinning method with water as coagulation bath.

5. The preparation method according to claim 4, characterized in that: The mass ratio of the keratin powder to the cellulose is 1:1, the mass fraction of the cellulose in the mixed solution is 2-3.5%, the mass fraction of the keratin in the mixed solution is 2-3.5%, and the mass of the glutamic acid esterified cellulose is 1-15% of the mass of the keratin powder.

6. The preparation method according to claim 4, characterized in that: The keratin powder is prepared by the following method: degreasing crude wool with a sodium bicarbonate aqueous solution and drying to obtain pretreated wool; immersing the pretreated wool in a treatment solution, stirring at 80-100° C. for 4-6 hours, centrifuging, and dialyzing the upper solution to obtain a keratin solution; adding a mixed solution of Na2SO4 and HCl to the keratin solution under stirring conditions, stirring for 3-5 minutes, and drying the obtained precipitate to obtain the keratin powder.

7. The preparation method according to claim 6, characterized in that: The treatment liquid is prepared by mixing urea, sodium dodecyl sulfate, L-cysteine ​​and water, and its pH value is 10-11; the molar concentration of urea in the treatment liquid is 6-8 mol / L, the molar concentration of sodium dodecyl sulfate is 0.01-0.02 mol / L, the mass of L-cysteine ​​is 10% of the weight of wool, and the mass of wool is 3-5 g.

8. The preparation method according to claim 4, characterized in that: The ionic liquid is 1-ethyl-3-methylimidazolium acetate, and the added amount thereof is 1-2 g, and the added amount of DMSO is 4-8 g.

9. The preparation method according to claim 6, characterized in that: The molar concentration of Na2SO4 in the Na2SO4 and HCl mixed solution is 1 mol / L, and the molar concentration of HCl is 1 mol / L.

10. Use of the composite fiber prepared by the preparation method according to any one of claims 4 to 9 in preparing functional textiles.

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