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

Abstract

The present invention provides glutamate-esterified cellulose, composite fibers, and preparation methods and applications thereof, relating to the technical field of composite fiber preparation. The present invention first prepares glutamate-esterified cellulose, which is then combined with keratin and cellulose to prepare composite cellulose. During this process, the glutamate-esterified cellulose acts as an emulsifier, improving the compatibility between keratin and cellulose, allowing the two to be combined. This greatly utilizes the high toughness of keratin fibers and the high strength of cellulose, ultimately producing a composite fiber with both high strength and high toughness. Furthermore, by regulating the degree of cellulose modification during the preparation of the glutamate-esterified cellulose and the amount of glutamate-esterified cellulose added, the performance of the composite fiber can be precisely controlled, ensuring the production of a composite fiber with excellent performance.

Description

Technical Field

[0001] The present 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 growing awareness of sustainable development in society, recycling waste textiles to produce regenerated fibers has become a research hotspot in the chemical fiber field. Among them, waste wool textiles, due to their high keratin content, are ideal raw materials for recovering protein and producing regenerated fibers. Ionic liquids, as one of the most promising green solvents, have been widely used in the recycling of waste wool textiles (Journal of Molecular Liquids, 2022, 350, 118595). However, wool keratin has a low relative molecular weight (10-50 kDa), and the regenerated keratin fibers have poor mechanical strength, making them impractical for practical application. One approach to overcoming these limitations is to blend them with high-molecular-weight biopolymers such as cellulose to modify their rheological properties, thereby improving spinnability and fiber strength. Waste cotton fabrics contain cellulose, which has a high molecular weight and high content. After pulverization, cellulose can be directly dissolved in ionic liquids as a cellulose raw material. 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 object of the invention, the present invention provides a method for preparing glutamate-esterified cellulose, comprising the following steps:

[0006] Powdered cellulose is dissolved in an ionic liquid, and N-phthaloyl-L-glutamic anhydride, dimethylacetamide and 4-dimethylaminopyridine are added. The mixture is 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 becomes transparent, and the grafted anhydride product is collected by filtration. The grafted anhydride product is added to dimethyl sulfoxide, the pH of the solution is adjusted to 9-10, and the mixture is stirred at 80-100°C for a certain period of time, followed by washing and drying to obtain the glutamate-esterified cellulose.

[0007] Preferably, the ionic liquid is 1-ethyl-3-methylimidazolium acetate, the amount of which added 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; 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 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 layer of the solution to obtain a keratin solution; adding a mixed solution of Na2SO4 and HCl to the keratin solution under stirring, stirring for 3-5 minutes, and drying the resulting precipitate to obtain the keratin powder.

[0014] Preferably, the treatment liquid is prepared by mixing urea, sodium lauryl 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 lauryl 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, and the added amount thereof is 1-2 g, and the added amount of DMSO is 4-8 g.

[0016] Preferably, the molar concentration of Na2SO4 in the mixed solution of Na2SO4 and HCl 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. Cellulose with such characteristics can be used as an emulsifier in the process of combining keratin and cellulose.

[0020] 2. The present invention provides a method for preparing composite fibers, using glutamic acid-esterified cellulose, keratin, and cellulose as raw materials, with glutamic acid-esterified cellulose used as an emulsifier. By adjusting the amount of glutamic acid-esterified cellulose added during this process, the compatibility of keratin and cellulose is increased while ensuring the stability of the spinning solution system, preventing the aggregation of glutamic acid-esterified cellulose and the formation of clumps, which can lead to fiber defects and thus affect the overall fiber structure and mechanical properties. This technical solution effectively solves the problem of poor compatibility and poor performance of composite fibers prepared using keratin and cellulose in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Figure 2 This is a flow chart of the production process for 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 diagram showing the state of using the composite fiber prepared in Example 2 of the present invention to suspend a heavy object; DETAILED DESCRIPTION

[0026] In order to make the objectives, 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 here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions 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 includes 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 glutamic acid esterified cellulose, comprising the following steps:

[0030] After dissolving powdered cellulose in an ionic liquid, a predetermined amount of N-phthaloyl-L-glutamic anhydride, dimethylacetamide (DMAC) and 4-dimethylaminopyridine (DMAP) are added, and the mixture is 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 for regeneration until the anhydrous ethanol becomes transparent, and the grafted anhydride product is collected by filtration. The grafted anhydride product is added to dimethyl sulfoxide (DMSO), and a 20% KOH solution is added to adjust the pH of the solution to 9-10. After stirring at 80-100°C for a certain period of time, the solution is thoroughly washed with deionized water, collected by filtration, and finally dried in a blast furnace for 1 hour to obtain glutamate-esterified cellulose.

[0031] In the above technical solution, cellulose is modified with N-phthaloyl-L-glutamic anhydride to produce glutamate-esterified cellulose, which has amphiphilic (hydrophilic and lipophilic) properties and can be used as an emulsifier. Specifically, the glutamate-esterified cellulose proposed in the present invention has both hydrophilic groups (such as carboxyl and amino groups) and hydrophobic groups (ester groups) in its molecular structure. This amphiphilic structure enables it to effectively establish interfaces between materials of different polarities, enhancing the compatibility between different components. Therefore, it is particularly suitable for materials with significant polarity differences, such as cellulose and keratin. Furthermore, the esterified groups can form a relatively stable interfacial film, which helps improve the mechanical properties of the blended fibers (such as tensile strength and toughness) and effectively controls the dispersion state of the fibers and keratin, avoiding undesirable phase separation.

[0032] In one 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 the powdered cellulose, the amount of dimethylacetamide added is 2-4g, and the amount of 4-dimethylaminopyridine added is 0.5 times the mass of the powdered cellulose. By regulating the amount of N-phthaloyl-L-glutamic anhydride, the amounts of other raw materials added, and the experimental conditions, a glutamate-esterified cellulose is prepared that can be used as an emulsifier in the preparation of keratin / cellulose composite fibers.

[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 the grafted anhydride product is added 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 glutamic acid esterified cellulose, comprising the following steps:

[0036] Preparation of keratin powder: After degreasing the raw wool with a sodium bicarbonate aqueous solution, the wool was washed with deionized water and dried for 12 hours to obtain pretreated wool; the pretreated wool was immersed in the treatment solution, stirred at 80-100°C for 4-6 hours, the mixed solution was centrifuged, the upper solution was collected, and the urea and small molecular peptides were removed by dialysis to obtain a keratin solution; under stirring conditions, a mixed solution of Na2SO4 and HCl was added to the keratin solution and stirred for 3-5 minutes to lower the pH of the solution to below the isoelectric point of keratin until a white flocculent precipitate appeared in the keratin solution, and the precipitate was collected by filtration and thoroughly washed with deionized water. The keratin was 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 used with water as a coagulation bath to obtain the 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 used in fields such as high-performance textiles (such as clothing, sportswear, functional textiles, etc.) with high performance requirements.

[0039] In the above technical solution, by using glutamic acid esterified cellulose as an emulsifier to prepare composite fibers together with keratin powder and cellulose, the emulsifier glutamic acid 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 glutamic acid 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 glutamic acid esterified cellulose can form an interfacial film between cellulose and keratin to reduce the interfacial tension between cellulose and keratin, so that the two can be better mixed. Furthermore, glutamate-esterified cellulose not only improves the compatibility between keratin and cellulose, leveraging the low-strength, high-toughness properties of keratin fibers and the high-strength, low-toughness properties of cellulose fibers, but also forms a crosslinking 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. These effects ensure the production of composite fibers with excellent mechanical properties. In particular, the crosslinking structure formed by glutamate-esterified cellulose with keratin through its polar groups has the potential to improve the hygroscopicity and air permeability of the composite fiber, endowing the composite fiber with 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] In one embodiment of the present invention, a treatment solution is prepared by mixing urea, sodium lauryl 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 lauryl sulfate is 0.01-0.02 mol / L, the mass of L-cysteine ​​is 10% of the weight of the pretreated wool, and the mass of the wool is 3-5 g. After the wool is added to the treatment solution, the stirring speed is 800-1500 rpm. The pH of the treatment solution can be adjusted by adding a 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 10-15 minutes, rotation speed 7000-8000 rpm.

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

[0044] As an embodiment of the present invention, the molar concentration of Na2SO4 in the mixed solution of Na2SO4 and HCl is 1 mol / L, and 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 mixture of ionic liquid and DMSO is 2-3.5%, the ionic liquid is 1-ethyl-3-methylimidazolium acetate, the amount of which is added 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 mixture is 2-3.5%, the mass fraction of keratin powder in the mixture 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 its processing method is a commonly used method in the art, so it is not described 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 glutamic acid 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. The mixture was stirred at 80° C. and 800 rpm for 1 hour. The dissolved solution was poured into an anhydrous ethanol coagulation bath for regeneration, and the anhydrous ethanol was replaced several times during the coagulation bath until the solution became transparent. Then, the grafted anhydride product was collected by filtration and further dried at 60° C. for 1 hour. 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. The solution was heated at 80° C. and stirred at 800 rpm for 1 hour. The solution was thoroughly washed with deionized water, then collected by filtration, and finally dried at 60° C. for 1 hour to obtain glutamate-esterified cellulose.

[0052] Example 2

[0053] This embodiment prepares a high-strength and tough 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 against deionized water at 25°C (3500 Da cellulose The keratin solution was filtered through a dialysis 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 was added dropwise to the keratin solution to lower the pH of the solution to below 4.5 until a white flocculent precipitate appeared in the keratin solution. The precipitate was collected by filtration and thoroughly washed with deionized water. The keratin was further freeze-dried for 24 hours, crushed, and sealed and stored at 5°C for further use. The weight ratio of the wool to the sodium bicarbonate aqueous solution was 1:20. The treatment solution was prepared by preparing urea, SDS, L-cysteine ​​and water, wherein the concentration of urea was 8 mol / L, the concentration of SDS was 0.02 mol / L SDS, the amount of which added was 100 mL, and the amount of L-cysteine ​​added was 10% of the weight of the wool.

[0055] 0.182 g of keratin powder, 0.002 g of glutamate esterified cellulose prepared in Example 1, 0.182 g of cotton pulp, 1 g of 1-ethyl-3-methylimidazolium acetate ionic liquid and 4 g of DMSO were mixed, stirred at 80° C. and 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 washed and dried to obtain wool keratin / cellulose composite fibers.

[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, 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 only difference between Examples 3 to 7 and Example 1 is that the amount of glutamic acid esterified cellulose added during the preparation of the spinning solution is different from that in Example 2. The other experimental parameters and experimental steps are the same as those in Example 2 and are not further described here. A comparison of the amount of glutamic acid esterified cellulose added in Examples 2 to 7 and the mechanical properties of the composite fibers produced under the corresponding conditions is shown in Table 1. As can be seen from the data in the table, as the amount of glutamic acid esterified cellulose added increases, the mechanical properties of the composite fibers first increase and then decrease. When the amount of glutamic acid esterified cellulose added is 5%, the mechanical properties of the composite fibers are optimal. The above phenomenon may be caused by the fact that when the amount of glutamic acid esterified cellulose added is too high, the glutamic acid esterified cellulose aggregates and forms clumps, 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 Corporation of the United States. Before testing, the composite fibers were equilibrated in an environment with a temperature of 23°C and a humidity of 65% for 12 hours. During the test, the sample was stretched at a speed of 20 mm / min and a test length of 20 mm, that is, 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 prepared 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 are not repeated here. Table 2 shows a comparison of the amount of N-phthaloyl-L-glutamic anhydride added in Examples 4 and 8 to 10 (this amount represents the multiple of the amount added relative to the mass of cellulose) and the properties of the composite fibers obtained under the corresponding conditions. As can be seen from the data in the table, when the amount of N-phthaloyl-L-glutamic anhydride added is too large, the performance of the composite fibers obtained is poor. This is because: the addition of N-phthaloyl-L-glutamic anhydride can modify the cellulose. When the amount of N-phthaloyl-L-glutamic anhydride added is too large, the cellulose is over-modified, causing excessive emulsifier molecules to accumulate at the contact interface between cellulose and keratin, making the spinning solution system unstable and the internal structure of the resulting composite fibers uneven, affecting the overall structure and mechanical properties of the fibers. Secondly, excessive glutamate groups may form an unstable interface structure, which impairs the toughness and strength of the composite fibers.

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

[0065]

[0066]

[0067] Comparative Example 1

[0068] The only 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. The preparation method includes the following steps:

[0069] The raw wool was immersed in a 0.2 mol / L sodium bicarbonate aqueous solution 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, and the upper clear green solution was collected to remove the wool residue, and dialyzed against deionized water at 25°C (3500 Da cellulose dialysis bag) for 3 days to remove urea and small molecule peptides to obtain a keratin solution, and under constant stirring, a mixed solution of 1 mol / L Na2SO4 and HCl is added dropwise to the keratin solution to lower 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, and 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 preparing 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-methylimidazolium 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 then washed and dried to obtain the wool keratin / cellulose composite fiber.

[0071] A comparison of the properties 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 the addition of glutamic acid esterified cellulose, the tensile strength of the composite fiber increased from 102.85 MPa in Comparative Example 1 to 146.15 MPa in Example 4, an increase of 42.1%. This may be because glutamic acid 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 glutamic acid esterified cellulose not only improves the compatibility, but also may affect the uniformity of the fiber structure, reducing the structural unevenness problem 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 solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing composite fibers by esterifying cellulose with glutamate, characterized in that: The steps include: Preparation of keratin powder; Preparation of composite fibers: Keratin powder, glutamic acid esterified cellulose, and cellulose are dissolved in a mixed solution of ionic liquid and DMSO to prepare a wool keratin / cellulose composite fiber spinning solution; the composite fibers are prepared by a wet spinning method using water as a coagulation bath; The preparation method of the glutamate-esterified cellulose comprises the following steps: Dissolve powdered cellulose in an ionic liquid, add N-phthaloyl-L-glutamic anhydride, dimethylacetamide and 4-dimethylaminopyridine, and heat and stir at 70-80°C for 2-3 hours. 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 to dimethyl sulfoxide, the pH value of the solution is adjusted to 9-10, and the solution is stirred at 80-100° C. for a certain period of time, and then washed and dried to obtain the glutamic acid esterified cellulose.

2. The method according to claim 1, characterized in that In the preparation method of glutamic acid esterified cellulose, 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 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. The method according to claim 1, wherein 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 glutamic acid esterified cellulose is 1-15% of the mass of the keratin powder.

5. The method according to claim 1, wherein 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 layer solution to obtain a keratin solution; Under stirring conditions, a mixed solution of Na2SO4 and HCl is added to the keratin solution, stirred for 3-5 minutes, and the obtained precipitate is dried to obtain the keratin powder.

6. The method according to claim 5, characterized in that The treatment liquid is prepared by mixing urea, sodium lauryl sulfate, L-cysteine ​​and water, and has a pH of 10-11. The molar concentration of urea in the treatment liquid is 6-8 mol / L, the molar concentration of sodium lauryl 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.

7. The method according to claim 1, 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.

8. The method according to claim 5, characterized in that The molar concentration of Na2SO4 in the mixed solution of Na2SO4 and HCl is 1 mol / L, and the molar concentration of HCl is 1 mol / L.

9. Use of the composite fiber prepared by the method according to any one of claims 1 to 8 in the preparation of functional textiles.

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