Highly filled regenerated cellulose-based functional composite material and preparation method thereof
阅读说明：本技术 高填充的再生纤维素基功能复合材料及其制备方法 (Highly filled regenerated cellulose-based functional composite material and preparation method thereof ) 是由 吴凯 刘丁侥 张永正 雷楚昕 于 2019-10-20 设计创作，主要内容包括：本发明公开了一种高填充的再生纤维素基功能复合材料及其制备方法。本发明通过将功能填料,强碱、尿素和水组成的溶液混合后球磨,得到功能填料的浆料,再与再生纤维素溶液机械搅拌混合,得到具有高可加工性的再生纤维素基前驱体浆料。利用本发明的再生纤维素基前驱体浆料通过湿法纺丝、铸膜、与环氧氯丙烷混合后倾倒入模具能够分别制备一维、二维和三维再生纤维素基功能复合材料。以本发明制得的前驱体浆料为基础原料,即使在高的填充含量下,填料依然能够稳定并均匀地分散在体系中,利于制备高性能的再生纤维素基复合材料,拓宽了再生纤维素基功能复合材料的应用的领域。(The invention discloses a high-filling regenerated cellulose-based functional composite material and a preparation method thereof. The method comprises the steps of mixing a solution consisting of functional filler, strong base, urea and water, then carrying out ball milling to obtain a slurry of the functional filler, and then mechanically stirring and mixing the slurry with a regenerated cellulose solution to obtain a regenerated cellulose-based precursor slurry with high processability. The regenerated cellulose-based precursor slurry can be used for preparing one-dimensional, two-dimensional and three-dimensional regenerated cellulose-based functional composite materials respectively by wet spinning, film casting, mixing with epoxy chloropropane, pouring into a mold after pouring. The precursor slurry prepared by the invention is used as a basic raw material, and even under the condition of high filling content, the filler can still be stably and uniformly dispersed in the system, so that the preparation of the high-performance regenerated cellulose-based composite material is facilitated, and the application field of the regenerated cellulose-based functional composite material is widened.)
1. The preparation method of the regenerated cellulose-based precursor slurry with high processability is characterized by comprising the following specific steps of:
step 1, mixing a solution consisting of functional filler, strong base, urea and water, and then carrying out ball milling to obtain slurry of the functional filler;
and 2, mixing the regenerated cellulose solution with the slurry of the functional filler by a mechanical stirring method to obtain regenerated cellulose-based precursor slurry.
2. The preparation method of the urea-water composite material according to claim 1, wherein in the step 1, the mass ratio of the urea to the water is 15:77, and the ratio of the mass of the strong base to the total mass of the urea and the water is 4-7: 46; the rotation speed of the ball milling is 200-900 rpm, and the ball milling time is 0.25-12 h; the strong base is potassium hydroxide, sodium hydroxide or lithium hydroxide.
3. The method according to claim 1, wherein the regenerated cellulose solution is prepared by the following method in step 1: dissolving a regenerated cellulose raw material in an aqueous solution consisting of strong base and urea at the temperature of between 15 ℃ below zero and 0 ℃, and performing circulating freeze thawing to obtain a colorless and transparent regenerated cellulose solution, wherein the strong base is potassium hydroxide, sodium hydroxide or lithium hydroxide.
4. The preparation method according to claim 1, wherein in the step 2, the mass concentration of the regenerated cellulose in the regenerated cellulose solution is 4-6%; the stirring speed of the mechanical stirring is 500-1000 rpm; in the regenerated cellulose-based precursor slurry, the functional filler accounts for 0-80% of the total mass of the regenerated cellulose and the filler.
5. The regenerated cellulose-based precursor slurry prepared according to the preparation method of any one of claims 1 to 4.
6. Nanocomposite material with a one-dimensional fibrous structure, prepared from a regenerated cellulose-based precursor slurry according to claim 5, characterized by being prepared by: preparing a regenerated cellulose-based composite material with a one-dimensional structure by taking precursor slurry as a spinning solution in a wet spinning way; preferably, in the wet spinning process, the extrusion speed is 0.6 mm-18 mm/min, and the draw ratio is 1-4.
7. Nanocomposite with a two-dimensional thin-film structure, prepared from a reconstituted cellulose-based precursor slurry according to claim 5, characterized by being prepared by: and dripping the precursor slurry on a casting plate, and preparing the regenerated cellulose-based composite material with the two-dimensional film structure by a film scraping method.
8. The nanocomposite as claimed in claim 7, wherein the thickness of the scratch film is 100 to 1500 μm, and the scratch speed is 5 to 80 m/min.
9. Nanocomposite with a three-dimensional aerogel structure, prepared from a reconstituted cellulose-based precursor slurry according to claim 5, characterized by being prepared by the following steps: and mixing the precursor slurry with epoxy chloropropane, pouring the mixture into a mold, and freeze-drying to obtain the regenerated cellulose-based composite material with the three-dimensional aerogel structure in a specific shape.
10. The nanocomposite as claimed in claim 9, wherein the mass of the epichlorohydrin is 50-140% of the mass of the regenerated cellulose.
Technical Field
The invention belongs to the technical field of preparation of functionalized regenerated cellulose-based nano composite materials, and relates to a highly-filled regenerated cellulose-based functional composite material and a preparation method thereof.
Background
The Regenerated Cellulose (RC) is used as a green and environment-friendly biomass material, has abundant storage capacity in the nature, is green and environment-friendly in processing mode, and has very attractive prospect in the field of replacing traditional petroleum-based high polymer materials (such as PP, PE and the like). The material prepared from the regenerated cellulose has excellent mechanical properties, and can be widely applied to the traditional polymer application fields such as fabrics, plastic bags, food packaging and the like. However, with the development of emerging technologies, such as wearable technology, a new demand is provided for polymer materials: it is required to have electrical conductivity, thermal conductivity, electromagnetic shielding and the like while maintaining its mechanical properties. The intrinsic characteristics of the regenerated cellulose material cannot meet the requirements of the development of the new material in the current era, so the development of the regenerated cellulose functionality has important significance for the application of the regenerated cellulose material in the field of new materials.
Introducing a filler with functionality into a polymer is a main method for developing the functionality of a polymer-based composite material, for example, the polymer can be endowed with electromagnetic shielding performance by adding the filler with high conductivity such as graphene, carbon nanotubes or silver nanowires into the polymer; the polymer is added with fillers such as alumina, boron nitride and the like with high thermal conductivity coefficient, so that the polymer can be endowed with better heat transfer performance. The filling content of the filler and its state of dispersion in the matrix are key factors affecting the properties of the composite. On the one hand, the functionality of the composite material can generally be significantly increased only if the filler content is sufficiently high. The traditional processing method for achieving high loading content is to achieve compounding of functional fillers and polymers by melt blending by applying strong shear forces to the filler and polymer melt during processing. However, because a large number of hydroxyl groups exist in the macromolecular chain of the cellulose, strong hydrogen bonds are formed among all the hydroxyl groups in the crystalline region of the cellulose, and therefore the cellulose cannot be blended with the functional filler by a melt processing method. The existing way of blending cellulose and filler is to directly mix the filler and regenerated cellulose solution by means of simple mechanical mixing. However, at high loading levels, it is difficult to achieve uniform dispersion of the filler in the matrix. This is because most functional fillers (such as boron nitride, graphene, carbon nanotubes, etc.) have few surface functional groups, and when the content of the fillers is too high, the fillers are easily agglomerated due to intermolecular forces, so that the mechanical properties, processability, etc. of the composite material are greatly reduced, and the composite material cannot be put into practical production and use, which is not favorable for the development of functional applications of cellulose-based composite materials. Therefore, how to simultaneously realize high filler content filling and uniform dispersion is a key problem which needs to be solved urgently in the field of cellulose-based functional composite materials.
Disclosure of Invention
One of the objects of the present invention is to provide a regenerated cellulose-based precursor slurry having high processability, comprising a regenerated cellulose solution and a functional filler, prepared by the steps of:
and 2, mixing the regenerated cellulose solution with the slurry of the functional filler by a mechanical stirring method to obtain regenerated cellulose-based precursor slurry.
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The second purpose of the invention is to provide a nano composite material with a one-dimensional fiber structure, which is prepared by the precursor slurry and comprises the following steps: the precursor slurry is used as spinning solution, and the regenerated cellulose-based composite material with a one-dimensional structure is prepared in a wet spinning mode.
Preferably, in the wet spinning process, the extrusion speed is 0.6 mm-18 mm/min, and the draw ratio is 1-4.
The invention also aims to provide a nano composite material with a two-dimensional film structure, which is prepared from the precursor slurry and is prepared by the following steps: and dripping the precursor slurry on a casting plate, and preparing the regenerated cellulose-based composite material with the two-dimensional film structure by a film scraping method.
Preferably, the thickness of the scraping film is 100-1500 μm, and the scraping speed is 5-80 m/min.
The fourth purpose of the invention is to provide a nanocomposite material with a three-dimensional aerogel structure, which is prepared from the precursor slurry, and the nanocomposite material is prepared by the following steps: and mixing the precursor slurry with epoxy chloropropane, pouring the mixture into a mold, and freeze-drying to obtain the regenerated cellulose-based composite material with the three-dimensional aerogel structure in a specific shape.
Preferably, the mass of the epichlorohydrin is 50-140% of the mass of the regenerated cellulose.
According to the invention, the surface energy of the filler is reduced by utilizing the p-pi conjugation effect or the hydrogen bond interaction between urea and the filler, and then the filler can be stably dispersed in a regenerated cellulose dissolving system through the hydrophobic-hydrophobic interaction or the hydrophilic-hydrophilic interaction between the regenerated cellulose and the nano filler, so that the precursor slurry with high processability is prepared. The slurry prepared by the method can be further processed to obtain the regenerated cellulose-based composite material with various structures and diversified functions from one dimension to three dimensions.
Compared with the prior art, the invention has the following advantages:
(1) compared with the traditional direct solution blending method, the invention provides the preparation method of the precursor slurry with better dispersibility. The precursor slurry prepared by the invention is used as a basic raw material, and even under the condition of high filling content, the filler can still be stably and uniformly dispersed in the system, thereby being beneficial to preparing the high-performance regenerated cellulose-based composite material.
(2) The precursor slurry prepared by the invention has good processing performance, and the regenerated cellulose-based composite materials with different structures can be obtained by spinning, blade coating or casting and other methods, thereby widening the application field of the regenerated cellulose-based functional composite materials.
Drawings
FIG. 1(a-b) is an SEM photograph showing the dispersion of BNNs in RC in example 1; FIG. 1(c-d) is an SEM photograph showing the dispersion of BNNs in RC in example 2.
FIG. 2(a) is a graph showing the results of apparent viscosities of precursor slurries prepared in examples 1 to 3; FIG. 2(b) is a graph showing the change in absorbance with time of the precursor slurries prepared in examples 1 to 3; FIG. 2(c) is a pictorial representation of a precursor slurry from the preparation of sheets of red for examples 1-3; FIG. 1(d) shows the results of infrared absorption spectrum in example 1; FIGS. 2(e-f) are graphs showing the results of Raman spectra of example 2 and example 3, respectively.
FIG. 3(a) is a physical representation of the RC/BNNs fibers obtained by wet spinning in example 1; FIG. 3(b) is a scanning electron microscope image of knotted individual fibers; FIG. 3(c) is a stress-strain curve of RC/BNNs fibers; FIG. 3(d) is a graph showing the results of thermal conductivity of the RC/BNNs fibers obtained in example 1.
FIG. 4(a) is a schematic representation of an RC/MWCNT thin film obtained by the coating method in example 2; FIG. 4(b) is a display view of a folded and bent film; FIG. 4(c) is a stress-strain curve of an RC/MWCNT thin film; FIG. 4(d) is a graph of thermal conductivity results for the RC/MWCNT thin film.
FIG. 5(a) is a physical diagram of the RC/GNP aerogel obtained by the freeze-drying method in example 3; FIG. 5(b) is a graph showing the results of electromagnetic shielding of the RC/GNP.
Detailed Description
The invention will be further described in detail below by way of examples and figures. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the teachings of the present invention are still within the scope of the present invention.
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