阅读说明：本技术 一种热塑性壳聚糖基纳米复合材料及其制备方法 (Thermoplastic chitosan-based nanocomposite and preparation method thereof ) 是由 刘晓东 王磊 陈寿 彭晓华 谷晓昱 杨卫民 周郑彬 王全兵 于 2020-05-14 设计创作，主要内容包括：本发明公开一种热塑性壳聚糖基纳米复合材料及其制备方法。方法包括步骤：将无机纳米粒子加入酸溶液中,进行超声分散,得到无机纳米粒子分散液；将壳聚糖与加工助剂在加热条件下混合,混合均匀后于密炼机中进行混炼,在所述混炼过程中加入无机纳米粒子分散液；将混炼后物料放入双螺杆挤出机中塑化均匀,制成热塑性壳聚糖纳米复合材料。采用本发明上述方法,可以减少无机纳米粒子在干燥过程中的团聚,实现无机纳米粒子在热塑性壳聚糖基体中的均匀分散,大幅提升热塑性壳聚糖基体的性能,且过程简单,易于操作,能够适用于规模化的生产。(The invention discloses a thermoplastic chitosan-based nanocomposite and a preparation method thereof. The method comprises the following steps: adding inorganic nano particles into an acid solution, and performing ultrasonic dispersion to obtain an inorganic nano particle dispersion liquid; mixing chitosan and a processing aid under a heating condition, uniformly mixing, and then mixing in an internal mixer, wherein an inorganic nano particle dispersion liquid is added in the mixing process; and putting the mixed materials into a double-screw extruder for uniform plasticization to prepare the thermoplastic chitosan nano composite material. By adopting the method, the agglomeration of the inorganic nanoparticles in the drying process can be reduced, the uniform dispersion of the inorganic nanoparticles in the thermoplastic chitosan matrix is realized, the performance of the thermoplastic chitosan matrix is greatly improved, the process is simple, the operation is easy, and the method can be suitable for large-scale production.)

1. A method for preparing a thermoplastic chitosan-based nanocomposite material is characterized by comprising the following steps:

adding inorganic nano particles into an acid solution, and performing ultrasonic dispersion to obtain an inorganic nano particle dispersion liquid;

mixing chitosan and a processing aid under a heating condition, uniformly mixing, and then mixing in an internal mixer, wherein an inorganic nano particle dispersion liquid is added in the mixing process;

and putting the mixed materials into a double-screw extruder for uniform plasticization to prepare the thermoplastic chitosan nano composite material.

2. The method for preparing a thermoplastic chitosan-based nanocomposite according to claim 1, wherein the inorganic nanoparticles are selected from one or more of carbon nanotubes, graphene, montmorillonite, vermiculite, hydrotalcite, kaolin, hectorite, and metal oxides.

3. The method for preparing a thermoplastic chitosan-based nanocomposite according to claim 1, wherein the acid solution is one of aqueous formic acid, aqueous acetic acid and aqueous citric acid, and the mass concentration of the acid solution is 1% to 5%.

4. The method for preparing a thermoplastic chitosan-based nanocomposite according to claim 1, wherein the mass concentration of the inorganic nanoparticles in the inorganic nanoparticle dispersion is 1% to 5%.

5. The method for preparing a thermoplastic chitosan-based nanocomposite material according to claim 1, wherein the power of the ultrasonic dispersion is 500-800W, and the time is 30-120 min.

6. The method for preparing a thermoplastic chitosan-based nanocomposite according to claim 1, wherein the viscosity value of chitosan is 100-1100 mpas.

7. A method for preparing a thermoplastic chitosan-based nanocomposite according to claim 1, wherein the processing aid is one of malic acid, citric acid, and maleic acid.

8. The method for preparing a thermoplastic chitosan-based nanocomposite material according to claim 1, wherein the mass ratio of the acid solution to the chitosan is 1-4: 1.

9. The method for preparing a thermoplastic chitosan-based nanocomposite material according to claim 1, wherein the mixing temperature is 60-85 ℃ and the mixing time is 15-20 min;

the temperature of each zone in the double-screw extruder is controlled to be 80-100 ℃.

10. A thermoplastic chitosan-based nanocomposite characterized by being produced by the production method according to any one of claims 1 to 9.

Technical Field

The invention relates to the field of polymer modification, in particular to a thermoplastic chitosan-based nanocomposite and a preparation method thereof.

Background

Chitosan is the only natural cationic basic polysaccharide in nature, and is obtained by deacetylating chitin, and the chitin is one of the main components of exoskeletons of crustaceans such as shrimps and crabs. The fishing and breeding yield of crustacean such as shrimps and crabs reaches 1446 ten thousand tons in 2016. Wherein, the breeding yield of the shrimps and the crabs in China as a producing and consuming kingdom is up to 412 million tons. In the processing and treatment process of the shrimps and crabs, a large amount of waste shrimp and crab shells are inevitably generated, and serious environmental pollution is caused. In order to meet the urgent needs of economic development and environmental protection, the technology development and accumulation in the related fields are accelerated, and the method has great economic and social benefits. The processability of chitosan is similar to that of starch, and the development of a modification technology of a thermoplastic chitosan material has important significance by using a processing and modification method of thermoplastic starch for reference.

The term "nanocomposite" was originally proposed by Roy et al in the beginning of the 80 th 20 th century and refers to a composite material in which a substance in one phase is dispersed in another phase on a nano-scale. The polymer-based inorganic nanocomposite material can perfectly combine the rigidity, dimensional stability and thermal stability of inorganic materials with the rigidity, processability and other properties of polymer materials; on the other hand, the inorganic material is in a nano scale, has unique performance due to surface effect, quantum size effect, volume effect and quantum tunneling effect, and after being compounded with the polymer, the mechanical property, the thermal property, the wear resistance, the molding processability of the polymer, the ultraviolet resistance and other properties of the composite material are greatly improved. Moreover, the preparation of polymer-based nanocomposites can be designed and manufactured according to the required properties, which is the biggest characteristic of the preparation of polymer-based inorganic nanocomposites.

The organic/inorganic particle type nanocomposite is generally prepared by a blending method. The method has the advantages that the preparation of the nano particles and the synthesis of the polymer are not carried out simultaneously, and the raw material supply and demand are wide. However, the problem is that the nano effect of the nanoparticles is likely to agglomerate, and the polymer matrix is mostly an organic phase, and the viscosity after melting is high, so that it is difficult for the nanoparticle powder to be uniformly dispersed in the polymer matrix to exert the maximum effect. The problem to be solved in the development of polymer nanocomposites is firstly to obtain a state of material with stable dimensions and secondly to be able to disperse the nanoparticles evenly in the polymer matrix.

Accordingly, the prior art is yet to be improved and developed.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a thermoplastic chitosan-based nanocomposite and a preparation method thereof, which aims to solve the problems that nanoparticles are easy to agglomerate and nanoparticle powder is difficult to be uniformly dispersed in a polymer matrix in the existing method for preparing an organic/inorganic particle type nanocomposite.

The technical scheme of the invention is as follows:

a method for preparing a thermoplastic chitosan-based nanocomposite, comprising the steps of:

adding inorganic nano particles into an acid solution, and performing ultrasonic dispersion to obtain an inorganic nano particle dispersion liquid;

mixing chitosan and a processing aid under a heating condition, uniformly mixing, and then mixing in an internal mixer, wherein an inorganic nano particle dispersion liquid is added in the mixing process;

and putting the mixed materials into a double-screw extruder for uniform plasticization to prepare the thermoplastic chitosan nano composite material.

Further, the inorganic nano-particles are selected from one or more of carbon nano-tubes, graphene, montmorillonite, vermiculite, hydrotalcite, kaolin, hectorite and metal oxides.

Further, the acid solution is one of a formic acid aqueous solution, an acetic acid aqueous solution and a citric acid aqueous solution, and the mass concentration of the acid solution is 1-5%.

Further, in the inorganic nanoparticle dispersion liquid, the mass concentration of the inorganic nanoparticles is 1% to 5%.

Furthermore, the power of ultrasonic dispersion is 500-800W, and the time is 30-120 min.

Further, the viscosity value of the chitosan is 100-1100 mpas.

Further, the cross-linking agent is one of malic acid, citric acid and maleic acid.

Further, the mass ratio of the acid solution to the chitosan is 1-4: 1.

Further, the mixing temperature is 60-85 ℃, and the mixing time is 15-20 min;

the temperature of each zone in the double-screw extruder is controlled to be 80-100 ℃.

The invention relates to a thermoplastic chitosan-based nano composite material, which is prepared by the preparation method.

Has the advantages that: by adopting the method, the agglomeration of the inorganic nanoparticles in the drying process can be reduced, the uniform dispersion of the inorganic nanoparticles in the thermoplastic chitosan matrix is realized, the performance of the thermoplastic chitosan matrix is greatly improved, the process is simple, the operation is easy, and the method can be suitable for large-scale production.

Drawings

In FIG. 1, (a) is a micrograph of thermoplastic chitosan, and (b) is a micrograph of a thermoplastic chitosan/carbon nanotube nanocomposite.

Fig. 2 (a) is a graph showing the tensile strength of the thermoplastic chitosan and thermoplastic chitosan/carbon nanotube nanocomposite, and (b) is a graph showing the elongation at break of the thermoplastic chitosan and thermoplastic chitosan/carbon nanotube nanocomposite.

Detailed Description

The invention provides a thermoplastic chitosan-based nanocomposite and a preparation method thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and more clear. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The embodiment of the invention provides a preparation method of a thermoplastic chitosan-based nanocomposite, which comprises the following steps:

adding inorganic nano particles into an acid solution, and performing ultrasonic dispersion to obtain an inorganic nano particle dispersion liquid;

mixing chitosan and a processing aid under a heating condition, uniformly mixing, and then mixing in an internal mixer, wherein an inorganic nano particle dispersion liquid is added in the mixing process;

and putting the mixed materials into a double-screw extruder for uniform plasticization to prepare the thermoplastic chitosan nano composite material.

The traditional polymer-based nanocomposite preparation methods can be divided into two categories: (1) the two-dimensional lamellar particles are intercalated, the two-dimensional lamellar particles are stripped by utilizing the strong shearing action in the double-screw processing process, but the shearing force in the processing process is limited, and only partial stripping can be realized; (2) the two-dimensional lamellar particles are stripped in advance, then surface modification is carried out, the particles are added into the polymer matrix in a powder form after drying, the process is complex, the cost is high, and the agglomeration of the nano particles in the drying process cannot be avoided, so that the performance of the nano material is influenced finally.

By the method, agglomeration of the inorganic nanoparticles in the processing process can be reduced, uniform dispersion of the inorganic nanoparticles in the thermoplastic chitosan matrix is realized, the performance of the thermoplastic chitosan matrix is greatly improved, the process is simple, the operation is easy, and the method can be suitable for large-scale production.

In one embodiment, the inorganic nanoparticles are selected from one or more of carbon nanotubes, graphene, montmorillonite, vermiculite, hydrotalcite, kaolin, hectorite, metal oxides, and the like, without limitation thereto.

In one embodiment, the acid solution is not limited to one of aqueous formic acid, aqueous acetic acid, aqueous citric acid, and the like, and the acid solution has a mass concentration of 1% to 5%.

In one embodiment, the inorganic nanoparticle dispersion liquid has a mass concentration of the inorganic nanoparticles of 1% to 5%.

In one embodiment, the power of the ultrasonic dispersion is 500-800W, and the time is 30-120 min.

In one embodiment, in order to ensure the processability of the thermoplastic chitosan material, the viscosity value of the chitosan is 100-1100 mpas.

In one embodiment, in order to ensure the acting force between the chitosan molecular chains and the mechanical properties of the product, the processing aid is one of malic acid, citric acid, maleic acid and the like, but is not limited thereto.

In one embodiment, the mass ratio of the acid solution to the chitosan is 1-4: 1.

In one embodiment, in order to ensure that the chitosan is fully plasticized, the mixing temperature is 60-85 ℃ and the mixing time is 15-20 min;

in one embodiment, in the double-screw extruder, in order to ensure uniform mixing of chitosan and nano particles, the temperature of each zone is controlled between 80 and 100 ℃.

The embodiment of the invention provides a thermoplastic chitosan-based nanocomposite, wherein the thermoplastic chitosan-based nanocomposite is prepared by the preparation method provided by the embodiment of the invention.

The present invention is described in detail below with reference to specific examples.

(1) Example 1

A preparation method of a thermoplastic chitosan-based nanocomposite material specifically comprises the following steps:

citric Acid (CA) was added to Chitosan (CTS) (CTS: CA 7:3 by mass) and mixed well. Preparing 5 parts of 3 wt% acetic acid aqueous solution, wherein each part of the aqueous solution is 3 times of the mass of CTS, respectively adding 1%, 2%, 3%, 4% and 5% carbon nano tubes of the mass of CTS, and performing ultrasonic treatment in an 800W power ultrasonic pulverizer for 20min to uniformly disperse the carbon nano tubes for later use. Mixing the CTS/CA mixture in an internal mixer at 80 ℃ for 10min at the rotating speed of 30rpm, respectively dropwise adding a carbon nano tube acetic acid aqueous solution into the mixture in the process, crushing the product, then placing the crushed product into a double-screw extruder for granulation, controlling the temperature of each zone to be 80-90 ℃, carrying out hot pressing on the prepared granules at 110 ℃ and 18MPa for 15min for molding, and drying the granules in an oven at 80 ℃ for 12h to obtain the CTS nano composite material.

As can be seen from FIG. 1, the CTS is in a semitransparent state, and the light transmittance is obviously reduced after 5% of MWCNTs is added, so that the MWCNTs are proved to realize good dispersion in a CTS matrix, and the feasibility of the preparation method of the nanocomposite is also proved.

As can be seen from FIG. 2, after the MWCNTs are added into the CTS matrix, the mechanical property of the CTS is obviously improved due to the toughening effect of the MWCNTs, and the mechanical property of the CTS shows a trend of increasing first and then decreasing along with the increase of the addition amount of the MWCNTs. The performance was best when the amount of MWCNTs added was 5%. The tensile strength is increased from 32.2MPa of CTS to 40.9MPa of CTS-5 percent MWCNTs nano composite material, and the increase range is 27 percent. The elongation at break is also improved from 4.75% to 6.03% of CTS, the improvement ratio is 2.69%, and the MWCNTs have obvious reinforcing and toughening effects on CTS matrix.

(2) Example 2

A preparation method of a thermoplastic chitosan-based nanocomposite material specifically comprises the following steps:

malic Acid (MA) was added to Chitosan (CTS) (CTS: CA 7:3, mass ratio) and mixed well. Preparing 5 parts of 3 wt% acetic acid aqueous solution, wherein each part of aqueous solution is 3 times of CTS in mass, adding 1%, 2%, 3%, 4% and 5% vermiculite in mass of CTS into the aqueous solution respectively, performing ultrasonic treatment in an 800W power ultrasonic pulverizer for 60min to uniformly disperse the vermiculite, and simultaneously peeling the vermiculite in the ultrasonic treatment process and stirring the vermiculite overnight for later use. Mixing the CTS/MA mixture in an internal mixer at 90 ℃ for 10min at the rotation speed of 20rpm, respectively dropwise adding a vermiculite acetic acid aqueous solution into the mixture in the process, crushing the product, then placing the product into a double-screw extruder for granulation, controlling the temperature of each zone to be 70-90 ℃, carrying out hot pressing on the prepared particles at 110 ℃ and 18MPa for 15min for molding, and drying the particles in an oven at 80 ℃ for 12h to obtain the CTS nano composite material.

In summary, according to the thermoplastic chitosan-based nanocomposite and the preparation method thereof provided by the invention, the agglomeration of inorganic nanoparticles in the drying process can be reduced, the uniform dispersion of the inorganic nanoparticles in the thermoplastic chitosan matrix is realized, the performance of the thermoplastic chitosan matrix is greatly improved, the process is simple, the operation is easy, and the method can be suitable for large-scale production.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.