A bacterial cellulose-calcium alginate aerogel fiber and a method of preparing the same
By preparing a spinning solution by mixing bacterial cellulose with sodium alginate and then solidifying it with calcium chloride, the problem of insufficient mechanical and torsional properties of aerogel fibers was solved, and bacterial cellulose-calcium alginate aerogel fibers with high strength and torsional resistance were prepared.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- QINGDAO UNIV
- Filing Date
- 2025-04-09
- Publication Date
- 2026-04-28
AI Technical Summary
Existing aerogel fibers have shortcomings in terms of mechanical and torsional properties. In particular, silica aerogel fibers have poor mechanical properties and shed powder, polyimide aerogels are complicated to prepare and are not environmentally friendly, and cellulose aerogel fibers have poor mechanical properties and are difficult to combine with high strength and torsional properties.
A spinning solution was prepared by mixing bacterial cellulose and sodium alginate. The solution was then solidified with calcium chloride and freeze-dried to form bacterial cellulose-calcium alginate aerogel fibers. The nanoscale spatial network of bacterial cellulose and the cross-linking effect of sodium alginate were used to form a 'reinforced concrete' structure to improve structural stability and mechanical properties.
It achieves structural stability and high mechanical properties of aerogel fibers, possesses excellent torsional resistance, and is also environmentally friendly.
Smart Images
Figure CN120231142B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aerogel fiber technology, specifically to a bacterial cellulose-calcium alginate aerogel fiber and its preparation method. Background Technology
[0002] Aerogel fibers have a three-dimensional network porous structure, low density, high porosity and low thermal conductivity. They can be used in fire suits, spacesuits and everyday thermal clothing. They have broad application prospects in thermal insulation and aerospace fields and are known as a new generation of thermal insulation materials.
[0003] Currently, aerogel fibers mainly include silica aerogel fibers, polyimide aerogel fibers, and cellulose aerogel fibers. Among them, silica aerogel fibers have poor mechanical properties, exhibit dust shedding, and have poor spinnability; polyimide aerogels have good mechanical properties, but their preparation process is complex, time-consuming, involves various organic solvents, is environmentally unfriendly, and has low torsional stiffness, making them difficult to process in textiles; cellulose aerogel fibers are typically prepared by dissolving cellulose in organic solvents such as DMSO, NMP, or DMAC to prepare a spinning solution, which is then extruded into a coagulation bath to produce aerogel fibers, but the resulting aerogel fibers have poor mechanical properties. Therefore, the preparation of aerogel fibers that combine high strength and torsional properties remains a technological bottleneck. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a bacterial cellulose-calcium alginate aerogel fiber and its preparation method.
[0005] The technical solution adopted in this invention is as follows:
[0006] A method for preparing bacterial cellulose-calcium alginate aerogel fibers, comprising the following steps:
[0007] (1) Prepare a bacterial cellulose suspension and add sodium alginate powder. Stir thoroughly to dissolve the sodium alginate and mix the bacterial cellulose and sodium alginate evenly to prepare a spinning solution.
[0008] (2) The spinning solution was extruded into the coagulation bath by an injection pump to obtain the shaped hydrogel fiber. The hydrogel fiber was transferred to the replacement solution to replace the water in the hydrogel fiber. Then it was frozen and dried to obtain bacterial cellulose-calcium alginate aerogel fiber.
[0009] Further, in step (1), the mass concentration of the bacterial cellulose suspension is 0.5-5.0%, and the mass ratio of the solid content of bacterial cellulose to sodium alginate is 0.2-5:1.
[0010] Furthermore, the solution used in the coagulation bath in step (2) is a calcium chloride solution with a mass concentration of 1-10%.
[0011] Further, in step (2), the replacement solution is an aqueous solution of ethanol, tert-butanol or propanol, and the volume concentration of the aqueous solution of ethanol, tert-butanol or propanol is 5-50%.
[0012] Furthermore, in step (2), the injection rate of the syringe pump is 50-300 mL / h.
[0013] Furthermore, in step (2), the freezing method is liquid nitrogen freezing or refrigerator freezing.
[0014] Furthermore, the freezing temperature in step (2) is -196℃ to -20℃.
[0015] The present invention also provides a bacterial cellulose-calcium alginate aerogel fiber, which is prepared using the above method.
[0016] The beneficial effects of this invention are as follows:
[0017] (1) This invention provides a method for preparing bacterial cellulose-calcium alginate aerogel fiber. The method involves preparing a spinning solution by mixing bacterial cellulose with sodium alginate and then solidifying it with calcium ions. At a certain concentration, bacterial cellulose can provide a continuous and non-agglomerated cellulose spatial network. The bacterial cellulose spatial network ensures the stable spatial structure and excellent torsional resistance of the aerogel fiber. Furthermore, the sodium alginate solution is uniformly dispersed on the surface of the bacterial cellulose nanofibers. After solidification with calcium chloride, the structural stability of the aerogel fiber is further ensured, thereby improving the mechanical properties and torsional resistance of the aerogel fiber.
[0018] (2) This invention provides a method for preparing bacterial cellulose-calcium alginate aerogel fiber, which uses bacterial cellulose and sodium alginate as raw materials. It has the characteristics of wide availability, biodegradability, renewability and environmental friendliness. In addition, sodium alginate also has flame retardancy, which also makes the prepared aerogel fiber have a certain flame retardancy. Attached Figure Description
[0019] To clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram illustrating the cross-linking effect of bacterial cellulose, sodium alginate, and calcium ions in this invention.
[0021] Figure 2 This is a scanning electron microscope image of the aerogel fiber prepared in Example 1 of the present invention. Detailed Implementation
[0022] This invention provides a bacterial cellulose-calcium alginate aerogel fiber and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0023] This invention provides a method for preparing bacterial cellulose-calcium alginate aerogel fibers, comprising the following steps:
[0024] (1) Prepare a bacterial cellulose suspension and add sodium alginate powder. Stir thoroughly to dissolve the sodium alginate and mix the bacterial cellulose and sodium alginate evenly to prepare a spinning solution.
[0025] Specifically, in this step, the mass concentration of the bacterial cellulose suspension is 0.5-5.0%, and the mass ratio of the solid content of bacterial cellulose to sodium alginate is 0.2-5:1.
[0026] (2) The spinning solution was extruded into the coagulation bath by an injection pump to obtain the shaped hydrogel fiber. The hydrogel fiber was transferred to the replacement solution to replace the water in the hydrogel fiber. Then it was frozen and dried to obtain bacterial cellulose-calcium alginate aerogel fiber.
[0027] Specifically, in this step, the coagulation bath uses a calcium chloride solution with a mass concentration of 1-10%; the replacement solution is an aqueous solution of ethanol, tert-butanol, or propanol, with a volume concentration of 5-50%; the injection rate of the syringe pump is 50-300 mL / h; and the freezing method is liquid nitrogen freezing or refrigerator freezing, with a freezing temperature of -196℃ to -20℃.
[0028] Through the above technical solution, the present invention solves the problems of poor mechanical properties and low torsional stiffness of aerogel fibers. Specifically, the present invention mainly solves this problem through the following aspects:
[0029] In the first aspect, the present invention utilizes the structural characteristics of bacterial cellulose, which has a nano-spatial network structure. By controlling its concentration, it is uniformly dispersed in an aqueous solution to form a continuous and non-agglomerated spatial network. The bacterial cellulose spatial network ensures the stable spatial structure and excellent torsion resistance of the aerogel fiber.
[0030] Secondly, this invention involves uniformly mixing bacterial cellulose and sodium alginate, spinning the mixture, and then solidifying it with a calcium chloride solution to obtain hydrogel fibers. These are then freeze-dried to obtain aerogel fibers. During the aerogel fiber formation process, the bacterial cellulose in the spinning solution acts as the "skeleton" of the aerogel fibers, while the sodium alginate solution is uniformly dispersed on the surface of the bacterial cellulose nanofibers. After solidification with calcium chloride to form calcium alginate, it becomes the "cement" of the aerogel fibers, creating a structure similar to "reinforced concrete." This ensures the structural stability of the aerogel fibers and improves their mechanical properties through the "reinforced concrete" connection. Furthermore, referring to… Figure 1 When bacterial cellulose and sodium alginate spinning solution are injected into calcium chloride solution, hydrogen bonds will form between the hydroxyl groups on bacterial cellulose and the hydroxyl and carboxyl groups on sodium alginate. At the same time, hydrogen bonds will also form between and within cellulose molecules. Hydrogen bonds will solidify and form hydrogel fibers through hydrogen bonding and calcium ion cross-linking.
[0031] Thirdly, in order to ensure the structural stability of bacterial cellulose and calcium alginate hydrogel fibers during freeze-drying, after the bacterial cellulose and calcium alginate hydrogel fibers are prepared, a low surface energy displacement solution, such as tert-butanol, is first used to displace the water in the bacterial cellulose and calcium alginate hydrogel fibers. After the displacement is completed, freeze-drying is then carried out.
[0032] Furthermore, in this invention, the above three aspects are combined and work together. If ordinary cellulose is used instead of bacterial cellulose, or if the concentration of bacterial cellulose is too low or too high, it is difficult to form an interconnected and continuous bacterial cellulose network. Even if sodium alginate is added to prepare cellulose-calcium alginate aerogel fibers, the torsional resistance cannot be guaranteed because the cellulose is not continuous in its spatial structure. If only bacterial cellulose is used without adding sodium alginate, calcium alginate cannot be coated on the bacterial cellulose, i.e., a "reinforced concrete" structure cannot be formed, resulting in poor structural stability and mechanical properties of the aerogel fibers, or even failure to form the fibers. If the hydrogel fibers are directly freeze-dried, the high surface energy of water will destroy the bond between bacterial cellulose and calcium alginate during the freeze-drying sublimation process, thereby damaging the aerogel fiber structure and reducing porosity and torsional resistance. This invention achieves structural stability, high mechanical properties, and torsional resistance of aerogel fibers through the combination of the above three aspects.
[0033] It should be noted that the mechanical properties of the aforementioned aerogel fibers mainly refer to tensile strength.
[0034] Furthermore, this invention does not impose any special restrictions on the source of any raw materials; they can be commercially available.
[0035] Example 1
[0036] This embodiment provides a bacterial cellulose-calcium alginate aerogel fiber, the preparation process of which is as follows:
[0037] (1) Prepare a 1wt% bacterial cellulose suspension, then add sodium alginate powder. The solid content mass ratio of bacterial cellulose to sodium alginate is 1:1. Stir thoroughly to dissolve sodium alginate and mix bacterial cellulose and sodium alginate evenly to prepare spinning solution.
[0038] (2) The spinning solution was extruded into a 3wt% calcium chloride solution using an injection pump at an injection speed of 80mL / h to obtain the formed hydrogel fiber. The hydrogel fiber was transferred to a 25% tert-butanol aqueous solution for 12h for replacement, and then frozen using liquid nitrogen at a freezing temperature of -196℃. Subsequently, it was placed in a freeze dryer for drying to obtain bacterial cellulose-calcium alginate aerogel fiber.
[0039] The bacterial cellulose-calcium alginate aerogel fibers prepared in Example 1 above were examined using scanning electron microscopy, such as... Figure 2 As shown, (a) is a scanning electron microscope (SEM) image of the overall cross-section of the aerogel fiber, and (b) is a SEM image of the aerogel on the aerogel fiber. From Figure 2 As can be seen, aerogel fibers have a three-dimensional network porous structure.
[0040] The aerogel fibers prepared in this embodiment have a porosity of 92%, a diameter of 903 μm, a tensile strength of 2.5 MPa, a single torsion limit of 21 r, and a thermal insulation coefficient of 0.03 W / (m·K).
[0041] Example 2
[0042] This embodiment provides a bacterial cellulose-calcium alginate aerogel fiber, the preparation process of which is as follows:
[0043] (1) Prepare a 0.5 wt% bacterial cellulose suspension, then add sodium alginate powder. The solid content mass ratio of bacterial cellulose to sodium alginate is 1:5. Stir thoroughly to dissolve sodium alginate and mix bacterial cellulose and sodium alginate evenly to prepare a spinning solution.
[0044] (2) The spinning solution was extruded into a 3wt% calcium chloride solution using an injection pump at an injection speed of 200mL / h to obtain the formed hydrogel fiber. The hydrogel fiber was transferred to a 10% ethanol aqueous solution for 12h for replacement, and then frozen using liquid nitrogen at a freezing temperature of -196℃. Subsequently, it was placed in a freeze dryer for drying to obtain bacterial cellulose-calcium alginate aerogel fiber.
[0045] The aerogel fibers prepared in this embodiment have a porosity of 90%, a diameter of 895 μm, a tensile strength of 3.7 MPa, a single torsion limit of 11 r, and a thermal insulation coefficient of 0.04 W / (m·K).
[0046] Example 3
[0047] This embodiment provides a bacterial cellulose-calcium alginate aerogel fiber, the preparation process of which is as follows:
[0048] (1) Prepare a 5wt% bacterial cellulose suspension, then add sodium alginate powder. The solid content mass ratio of bacterial cellulose to sodium alginate is 5:1. Stir thoroughly to dissolve sodium alginate and mix bacterial cellulose and sodium alginate evenly to prepare spinning solution.
[0049] (2) The spinning solution was extruded into an 8wt% calcium chloride solution using an injection pump at an injection speed of 80mL / h to obtain the formed hydrogel fiber. The hydrogel fiber was transferred to a 40% tert-butanol aqueous solution for 12h and then frozen using liquid nitrogen at a freezing temperature of -196℃. Subsequently, it was placed in a freeze dryer for drying to obtain bacterial cellulose-calcium alginate aerogel fiber.
[0050] The aerogel fibers prepared in this embodiment have a porosity of 85%, a diameter of 1043 μm, a tensile strength of 7.3 MPa, a single torsion limit of 28 r, and a thermal insulation coefficient of 0.04 W / (m·K).
[0051] Comparative Example 1
[0052] The difference between this comparative example and Example 1 is that the cellulose in this comparative example is nanocellulose (fibrous nanocellulose) prepared by TEMPO oxidation, and bacterial cellulose is not used.
[0053] The aerogel fibers prepared in this comparative example were found to have a porosity of 91%, a diameter of 880 μm, a tensile strength of 1.5 MPa, a single torsional limit of 8 r, and a thermal insulation coefficient of 0.03 W / (m·K).
[0054] Comparative Example 2
[0055] The difference between this comparative example and Example 1 is that the concentration of bacterial cellulose in this comparative example is 0.03 wt%.
[0056] The aerogel fibers prepared in this comparative example were tested and found to have a porosity of 96%, a diameter of 830 μm, a tensile strength of 0.8 MPa, a single torsional limit of 3 r, and a thermal insulation coefficient of 0.03 W / (m·K).
[0057] Comparative Example 3
[0058] The difference between this comparative example and Example 1 is that this comparative example only uses bacterial cellulose and does not add sodium alginate.
[0059] The aerogel fibers in this comparative example could not be molded.
[0060] Comparative Example 4
[0061] The difference between this comparative example and Example 1 is that, after obtaining the shaped hydrogel fibers in the coagulation bath, this comparative example is directly freeze-dried.
[0062] Testing revealed that the aerogel fibers prepared in this comparative example had a porosity of 66%, a diameter of 307 μm, a tensile strength of 178.4 MPa, a single torsional limit of 1 r, and a thermal insulation coefficient of 0.2 W / (m·K). This is because it is difficult to maintain a porous structure during direct freezing, resulting in a particularly low porosity, which in turn increases the thermal insulation coefficient and provides high tensile strength.
[0063] It should be noted that any parts not mentioned in this invention can be achieved by using or referencing existing technologies.
[0064] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.
Claims
1. A method for preparing bacterial cellulose-calcium alginate aerogel fibers, characterized in that, Including the following steps: (1) Prepare a bacterial cellulose suspension and add sodium alginate powder. Stir thoroughly to dissolve the sodium alginate and mix the bacterial cellulose and sodium alginate evenly to prepare a spinning solution. (2) The spinning solution was extruded into the coagulation bath by an injection pump to obtain the formed hydrogel fiber. The hydrogel fiber was transferred to the replacement solution to replace the water in the hydrogel fiber. Then it was frozen and dried to obtain bacterial cellulose-calcium alginate aerogel fiber. In step (1), the mass concentration of the bacterial cellulose suspension is 0.5-5.0%, and the mass ratio of the solid content of bacterial cellulose to sodium alginate is 0.2-5:
1.
2. The method for preparing bacterial cellulose-calcium alginate aerogel fiber according to claim 1, characterized in that, The solution used in the coagulation bath in step (2) is a calcium chloride solution with a mass concentration of 1-10%.
3. The method for preparing bacterial cellulose-calcium alginate aerogel fiber according to claim 1, characterized in that, In step (2), the replacement solution is an aqueous solution of ethanol, tert-butanol or propanol, and the volume concentration of the aqueous solution of ethanol, tert-butanol or propanol is 5~50%.
4. The method for preparing bacterial cellulose-calcium alginate aerogel fiber according to claim 1, characterized in that, In step (2), the injection rate of the syringe pump is 50~300 mL / h.
5. The method for preparing bacterial cellulose-calcium alginate aerogel fiber according to claim 1, characterized in that, In step (2), the freezing method is liquid nitrogen freezing or refrigerator freezing.
6. The method for preparing bacterial cellulose-calcium alginate aerogel fiber according to claim 1, characterized in that, The freezing temperature in step (2) is -196℃ to -20℃.
7. A bacterial cellulose-calcium alginate aerogel fiber, prepared by any one of claims 1-6.