WO2016074392A1

WO2016074392A1 - Method for preparing high-strength and high-modulus polyvinyl alcohol-graphene nano composite fibres

Info

Publication number: WO2016074392A1
Application number: PCT/CN2015/074138
Authority: WO
Inventors: 拜永孝; 胡新军; 沙嫣; 沙晓林
Original assignee: 上海史墨希新材料科技有限公司
Priority date: 2014-11-10
Filing date: 2015-03-12
Publication date: 2016-05-19
Also published as: CN104328533A

Abstract

Disclosed is a method for preparing high-strength and high-modulus polyvinyl alcohol-graphene nano composite fibres, comprising uniformly mixing graphene and polyvinyl alcohol in a mixed solvent; spinning by a gel spinning method; and carrying out hot stretching at a high ratio to obtain the high-strength and high-modulus polyvinyl alcohol-graphene nano composite fibres. The present invention has cheap raw materials, a simple production process and can easily realize industrial large-scale production. The prepared polyvinyl alcohol-graphene nano composite fibres have a tensile strength of 1.4 GPa-2.2 GPa, a Young's modulus of 36 GPa, an elongation at break of 10%, smooth surfaces of the fibres with the sections of the fibres being round, and can meet the requirements on high-strength and high-modulus polyvinyl alcohol fibres in special fields and the fields of construction and industry.

Description

Preparation method of high strength and high modulus polyvinyl alcohol-graphene nano composite fiber

Technical field

The invention relates to a preparation method of high strength and high modulus polyvinyl alcohol-graphene nano composite fiber.

Background technique

High-strength polyvinyl alcohol (PVA) fiber has good hydrophilicity, cohesiveness, impact resistance and easy dispersion during processing, so it is used as a reinforcing material in cement, asbestos sheet, ceramic building materials and polymer-based composite materials. There are many applications in the field. Reinforced concrete and building materials with high-strength PVA fiber can effectively improve the impact resistance, elastic fatigue and crack resistance of the material. The geotextile made of high-strength PVA fiber has high tensile strength, good creep resistance, excellent wear resistance, chemical corrosion resistance, microbial resistance and water conductivity, and can be used for reinforcement, isolation, protection and drainage during construction. And leakage prevention, can be used for various dams, as well as roads, railways, bridges, tunnels, slurry, sand and other projects, such as sand separation, reinforcement, bedding, stable foundation and waterproof isolation, etc., can significantly improve construction quality and reduce Engineering costs. Epoxy resin is used to bond high-strength PVA fibers into rods instead of steel bars in concrete, which can be used as civil engineering materials to greatly reduce the weight of building components. Due to the high breaking strength, impact strength, weather resistance and seawater corrosion resistance of high-strength PVA fiber, it is suitable for various types of fishing nets, fishing gear, fishing lines, ropes, etc., in marine fishing and transportation. Tools and other aspects have a good application market. Although the tensile strength and modulus of high-strength PVA fiber are not as good as those of Kevlar and UHMW-PE fiber, the fracture ratio is large, the adhesion is good, the price is low, etc., and it is possible to partially replace the price in the protective composite material. Kevlar fiber and so on. Therefore, the development of high-strength and high-modulus polyvinyl alcohol-graphene (PVA-Graphene) nanocomposite fibers has important research value, great application prospect and market potential.

With the continuous advancement of society, the requirements for material properties are getting higher and higher, and the existing polyvinyl alcohol fiber can not meet the requirements. Therefore, the preparation of high-strength and high-modulus PVA-Graphene nano-composite fiber is particularly important. The high-strength and high-modulus of fibers depends on both their chemical structure and molecular structure, as well as on their supramolecular structure. The theoretical ultimate strength of PVA is 27 GPa and the crystal modulus is 255 GPa, respectively. The highest modulus of the PVA fiber produced so far is 115 GPa. In order to obtain high-performance fiber materials and expand its application range, the strength and modulus of PVA fiber have further room for improvement. Therefore, it is necessary and urgent to obtain high-strength and high-modulus nanocomposites through material structure design and compounding process. of.

Carbon is widely found in nature and is one of the basic elements that make up living organisms. Graphene (Graphene) is a new carbonaceous material composed of a dense layer of monoatomic atoms formed by sp ² hybridization of carbon atoms entrapped on the lattice of honeycomb crystals. It is the basic unit that constitutes other carbon allotropes. It can be folded into zero-dimensional fullerenes, crimped into one-dimensional carbon nanotubes, and stacked into three-dimensional graphite and diamond. Excellent crystallinity and electrical properties and excellent mechanical properties. Graphene has high strength and performance comparable to diamond. The measured tensile strength and elastic modulus are 125GPa and 1.1T Pa, respectively. The graphene sheet has only one atomic layer thickness (0.335nm), which is only one part of the hair. It is the thinnest and hardest material known in the world. In addition, graphene has a large specific surface area and excellent mechanical properties, and is widely used in new high-strength nanocomposites. The invention utilizes the ultra-large specific surface area of graphene and excellent mechanical properties to prepare high-strength and high-modulus PVA-Graphene nano-composite fibers by gel spinning.

Summary of the invention

The object of the present invention is to provide a preparation method of high-strength and high-modulus polyvinyl alcohol-graphene nano-composite fiber with simple production process and low cost.

The object of the present invention is achieved by the following technical solutions:

The invention relates to a method for preparing a high-strength and high-modulus polyvinyl alcohol-graphene nano-composite fiber. After the graphene or graphene derivative and the polyvinyl alcohol are uniformly mixed in a mixed solvent, the method is spun by a gel spinning method. Silk, high-stretching to obtain high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers.

As a preferred technical solution, the graphene or graphene derivative is selected from the group consisting of graphene oxide, or one of the graphene-derived materials in which the graphene prepared by any method and means is hydrophilically modified or modified; The polyvinyl alcohol has a degree of polymerization of 1750 to 2488 and a degree of alcoholysis of 80 to 99% (that is, alcoholysis of polyvinyl acetate in an aqueous solution of methanol to dissolve 80 to 99% of the acetic acid in the polyvinyl acetate molecule. Becomes a hydroxyl group). When the degree of polymerization of the selected polyvinyl alcohol is less than 1750, since the molecular chain of the polyvinyl alcohol is short, the stretching ratio after gel spinning is small, and the molecular chain of the polyvinyl alcohol in the nanocomposite fiber cannot be effectively from the random The wire clusters form an ordered regular stretched condensed structure. When the degree of polymerization of polyvinyl alcohol is higher than 2488, the viscosity of the spinning solution is too large due to the large molecular weight, which is very disadvantageous for gel spinning, and the spinning cost is high and the operation is difficult. If the degree of alcoholysis of the polyvinyl alcohol used is less than 80%, the polyvinyl alcohol cannot be completely dissolved in the mixed solvent used in this patent, and the spinning process is difficult to proceed smoothly.

As a preferred technical solution, the graphene or graphene derivative and the polyvinyl alcohol are uniformly mixed in a mixed solvent to obtain a spinning dope, wherein the spinning solution has a mass percentage of polyvinyl alcohol of 10 to 25%, and graphene. Or the mass percentage of the graphene derivative is 0.1 to 10% of the mass of the polyvinyl alcohol matrix. When the polyvinyl alcohol in the spinning dope is selected to have the above concentration, the graphene composite spinning solution has a moderate viscosity, which is advantageous for the gel spinning process. Stable, the structural defects in the filament are less, and the performance of the composite fiber is good. Meanwhile, when the graphene or graphene derivative in the spinning dope is selected from the above concentrations, the graphene or graphene derivative can be completely dispersed in the polyvinyl alcohol matrix, and the graphene has a small stack. The uniform dispersion degree is high, the reinforcing effect is obvious, and the nano-composite fiber has good filament forming performance. In addition, this concentration range of the addition amount of graphene or graphene derivative does not affect or lose the intrinsic comprehensive mechanical properties such as the toughness of the polyvinyl alcohol fiber.

As a preferred technical solution, the mixing process is specifically: adding a graphene or a graphene derivative to a mixed solvent, and after ultrasonic dispersion, adding polyvinyl alcohol under mechanical stirring, and stirring to the polyethylene at 50 to 120 ° C The alcohol is dissolved.

As a preferred technical solution, the mixed solvent is prepared by mixing an organic solvent having a weight ratio of 95:5 to 70:30 and water; the organic solvent is selected from the group consisting of dimethyl sulfoxide, ethylene glycol, propylene glycol, glycerin, and n-butyl One or more of an alcohol, isobutanol, triethylene glycol, and tetrahydrofuran.

As a preferred technical solution, the ultrasonic dispersion time is 1 to 6 hours.

As a preferred technical solution, the gel spinning is specifically: the graphene or the graphene derivative and the polyvinyl alcohol are uniformly mixed in a mixed solvent to obtain a spinning dope, and the spinning dope is at 80 to 120 ° C. After filtration and defoaming, it is sprayed through a spinneret into a methanol coagulation bath of -15 to 5 ° C, and the spinning dope is quenched to form nascent fibers.

Preferably, the defoaming mode is selected from the group consisting of vacuum defoaming and atmospheric degassing; the spinneret has a pore size ranging from 0.06 to 0.15 mm and a number of pores of from 1 to 6,000.

In a preferred embodiment, the high-strength stretching is specifically: the nascent fibers obtained by gel spinning are sequentially subjected to extraction and drying, and the hot stretching temperature is 120 to 240° C., the stretching ratio is 8 to 36 times, and heat setting is performed. The hot stretching was carried out under the conditions of 1 to 15 minutes. By high-stretching (8 to 36 times), the crystallinity and orientation of the fiber can be increased, and the platelets in the folded chain can be transformed into a straight chain to obtain an ultrahigh-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fiber. . In the high-stretching process, not only the macromolecular chains in the finished fiber can be arranged in a regular arrangement, but also the graphene sheets are arranged in an orderly orientation in the fiber matrix to form a brick wall topology similar to the mollusc nacre. An organic non-machine layer structure is very advantageous for dispersing and transmitting external gravitation, and can effectively absorb, transfer and transfer loads, thereby significantly improving the comprehensive mechanical properties of the graphene nanocomposite fibers.

As a preferred embodiment, the extraction temperature is 20-80 ° C, the time is 2-60 min, and the extracting agent used is selected from methanol or ethanol; the drying temperature is 60-120 ° C, and the drying time is 2-24 h.

Compared with the prior art, the present invention has the following beneficial effects:

1. Polyvinyl alcohol can be used as a dispersing agent to uniformly disperse graphene or graphene derivatives in a mixed solvent.

2, gel spinning is the use of polyvinyl alcohol with high molecular weight, dissolved into a semi-dilute solution, the entanglement between macromolecular chains is greatly reduced, quenching after spinning makes this macromolecular chain The unwrapped state is maintained in the prepared gel precursor, and the crystallinity and degree of orientation of the fiber are increased by high-tensile heat stretching, so that the platelets in the folded chain are transformed into the straight chain. Thereby obtaining ultra high strength and high modulus graphene nanocomposite fibers. In the high-stretching, not only the macromolecular chain in the finished fiber can be arranged in a regular arrangement, but also the graphene sheets can be regularly aligned to further improve the comprehensive performance of the fiber.

DRAWINGS

Other features, objects, and advantages of the present invention will become apparent from the Detailed Description of the Description of the Description

1 is a schematic diagram of preparation of high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers;

2 is an SEM image (scanning electron micrograph) of a cross section of a polyvinyl alcohol-graphene nanocomposite fiber.

detailed description

The invention will be described in detail below with reference to the drawings and specific embodiments. The following examples are intended to further understand the invention, but are not intended to limit the invention in any way. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the inventive concept. These are all within the scope of protection of the present invention.

The schematic diagram of the preparation of the high-strength high-modulus polyvinyl alcohol-graphene nano-composite fiber of the present invention is shown in FIG. 1. The gel spinning of the present invention utilizes polyvinyl alcohol having a relatively high molecular weight and is dissolved into a semi-dilute solution. The entanglement between the macromolecular chains is greatly reduced, and the quenching after spinning allows the untwisted state between the macromolecular chains to be maintained in the prepared gel precursor, and the fiber is improved by the ultra-high heat stretching. The crystallinity and degree of orientation convert the platelets in the folded chain to the extended chain, thereby obtaining ultra-high strength and high modulus graphene nanocomposite fibers. In the high-stretching, not only the macromolecular chain in the finished fiber can be stretched in a regular arrangement, but also the graphene sheets can be aligned to further improve the performance of the fiber. See the following examples for details.

Example 1

The present embodiment relates to a method for preparing a high-strength and high-modulus polyvinyl alcohol-graphene nano-composite fiber. After uniformly mixing graphene and polyvinyl alcohol in a mixed solvent, spinning by a gel spinning method, high heat Tensile to obtain high strength and high modulus polyvinyl alcohol-graphene nanocomposite fibers. Specifically, the following steps are included:

(1) Add graphene oxide to a mixed solvent of dimethyl sulfoxide and water in a weight ratio of 90:10, ultrasonically disperse for 3 hours, and then add polyvinyl alcohol (degree of polymerization 2488±50, degree of alcoholysis is 95%) ), the dissolution temperature is 100 ° C; a spinning dope is formed. The spinning solution had a polyvinyl alcohol concentration of 15% by weight and a graphene oxide mass percentage of 1% by mass of the polyvinyl alcohol matrix.

(2) Dissolve the prepared spinning dope at a temperature of 100 ° C, after filtration and vacuum defoaming, and then spray it through a spinneret (the orifice of the spinneret 0.1 mm, the number of holes 2000 to 2500) to -5 to 0 ° C. Spinning stock solution at low temperature in a methanol coagulation bath It is quenched to form nascent fibers.

(3) The above-mentioned post-spinning treatment: extracting, drying and hot-stretching the nascent fibers to obtain high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers. The extractant was methanol, the extraction temperature was 50 ° C, the time was 30 min, the drying temperature was 100 ° C, the drying time was 12 h, the hot stretching temperature was 180 ° C, the stretching ratio was 30 times, and the heat setting time was 8 min.

The SEM photograph of the cross section of the high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fiber obtained in this embodiment is shown in FIG. 2. As can be seen from FIG. 2, the cross-sectional shape of the graphene nanocomposite polyvinyl alcohol fiber is substantially close to a circle. There is no disadvantage that the core layer is easy to be produced when the general nano-composite fiber is prepared; from the SEM photograph, the graphene nano-composite fiber prepared by the invention has no obvious structural defects, the composite fiber structure is uniform, the organic phase and the nano-filler are firmly combined, and there is no The phase separation and void defects, uniform dispersion of the filler, and continuous scale preparation are an ideal nanocomposite fiber material.

Example 2

(1) Adding modified graphene to a mixed solvent of ethylene glycol and water in a weight ratio of 95:5, ultrasonically dispersing for 1 h, and then adding polyvinyl alcohol (degree of polymerization 1750±50, degree of alcoholysis is 80%) The dissolution temperature was 50 ° C; a spinning dope was formed. The spinning solution has a polyvinyl alcohol concentration of 10% by weight and a graphene oxide mass percentage of 10% by mass of the polyvinyl alcohol matrix.

(2) Dissolve the prepared spinning dope at a temperature of 80 ° C, after filtration and atmospheric degassing, and then spray it to -15 ～ through a spinneret (pore plate aperture 0.06 mm, number of holes 200-1000). In a methanol coagulation bath of -10 ° C, the spinning dope is quenched to form nascent fibers at a low temperature.

(3) The above-mentioned post-spinning treatment: extracting, drying and hot-stretching the nascent fibers to obtain high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers. The extractant was methanol, the extraction temperature was 20 ° C, the time was 2 min, the drying temperature was 60 ° C, the drying time was 2 h, the hot stretching temperature was 120 ° C, the stretching ratio was 8 times, and the heat setting time was 1 min.

The SEM analysis of the high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers prepared in this example showed that the fiber surface was smooth, there were no obvious structural defects, the composite fiber structure was uniform, the organic phase and the nano-filler were firmly combined, and there was no phase separation. Defects with voids and uniform dispersion of the filler; the cross-sectional shape is nearly round.

Example 3

The embodiment relates to a method for preparing high strength and high modulus polyvinyl alcohol-graphene nano composite fiber, and graphite After the olefin and the polyvinyl alcohol are uniformly mixed in a mixed solvent, they are spun by a gel spinning method, and a high-strength high-mode polyvinyl alcohol-graphene nanocomposite fiber is obtained by high-stretching. Specifically, the following steps are included:

(1) Electrochemically stripped graphene was added to a mixed solvent of tetrahydrofuran, n-butanol and water at a weight ratio of 70:30, ultrasonically dispersed for 6 h, and then polyvinyl alcohol was added (degree of polymerization 2488 ± 50, degree of alcoholysis) 95%), the dissolution temperature was 120 ° C; a spinning dope was formed. The spinning solution had a polyvinyl alcohol concentration of 25% by weight and a graphene oxide mass percentage of 0.1% by mass of the polyvinyl alcohol matrix.

(2) Dissolve the prepared spinning dope at a temperature of 120 ° C, after filtration and vacuum defoaming, and spray it to -10 to -5 ° C through a spinneret (a spinneret hole diameter of 0.15 mm, a number of holes of 5000 to 6000). In the methanol coagulation bath, the spinning dope is quenched to form nascent fibers at a low temperature.

(3) The above-mentioned post-spinning treatment: extracting, drying and hot-stretching the nascent fibers to obtain high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers. The extractant was ethanol, the extraction temperature was 80 ° C, the time was 60 min, the drying temperature was 120 ° C, the drying time was 24 h, the hot stretching temperature was 240 ° C, the stretching ratio was 36 times, and the heat setting time was 15 min.

Example 4

(1) Adding graphene prepared by mechanical stripping method in a mixed solvent of glycerin and water in a weight ratio of 80:20, ultrasonically dispersing for 2 h, and then adding polyvinyl alcohol (degree of polymerization 2088±50, degree of alcoholysis is 90%) ), the dissolution temperature is 80 ° C; forming a spinning dope. The spinning solution had a polyvinyl alcohol concentration of 20% by weight and a graphene oxide mass percentage of 2% by mass of the polyvinyl alcohol matrix.

(2) Dissolve the prepared spinning dope at a temperature of 105 ° C, after filtration and atmospheric degassing, and then spray it to 0 to 5 through a spinneret (a spinneret hole diameter of 0.12 mm, a number of holes of 2000 to 2500). In the methanol coagulation bath of °C, the spinning dope is quenched to form nascent fibers at a low temperature.

(3) The above-mentioned post-spinning treatment: extracting, drying and hot-stretching the nascent fibers to obtain high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers. The extractant was ethanol, the extraction temperature was 60 ° C, the time was 25 min, the drying temperature was 80 ° C, the drying time was 20 h, the hot stretching temperature was 180 ° C, the stretching ratio was 20 times, and the heat setting time was 10 min.

The SEM analysis of the high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers prepared in this example showed that the fiber surface was smooth, there were no obvious structural defects, the composite fiber structure was uniform, the organic phase and the nano-filler were firmly combined, and there was no phase separation. And the defect of voids, the filler is evenly dispersed; the cross-sectional shape is circular.

Example 5

The mechanical properties of the high strength and high modulus polyvinyl alcohol-graphene nanocomposite fibers prepared in the above Examples 1 to 4 were tested; the results are shown in Table 1.

Table 1

In Table 1, the comparative example was prepared in the same manner as in Example 1, except that only polyvinyl alcohol was used, and graphene oxide was not added. It can be seen from Table 1 that the polyvinyl alcohol-graphene nanocomposite fiber obtained by the method of the invention has excellent tensile strength and Young's modulus, and can satisfy high strength and high modulus polyvinyl alcohol in special fields, construction and industrial fields. Fiber requirements.

The specific embodiments of the present invention have been described above. It is to be understood that the invention is not limited to the specific embodiments described above, and various modifications and changes may be made by those skilled in the art without departing from the scope of the invention.

Claims

Method for preparing high-strength and high-modulus polyvinyl alcohol-graphene nano-composite fiber, characterized in that a method of gel spinning by uniformly mixing graphene or graphene derivative and polyvinyl alcohol in a mixed solvent Spinning, high-stretching to obtain high-strength and high-modulus polyvinyl alcohol-graphene nanocomposite fibers.
The preparation method according to claim 1, wherein the graphene or graphene derivative is selected from the group consisting of graphene oxide, or a hydrophilically modified or modified graphene-derived material; The degree of polymerization is from 1750 to 2488, and the degree of alcoholysis is from 80 to 99%.
The preparation method according to claim 1 or 2, wherein the graphene or graphene derivative and the polyvinyl alcohol are uniformly mixed in a mixed solvent to obtain a spinning dope, and the spinning dope contains polyvinyl alcohol. The mass percentage concentration is 10 to 25%, and the mass percentage of the graphene or graphene derivative is 0.1 to 10% by mass of the polyvinyl alcohol matrix.
The preparation method according to claim 1, wherein the mixing is specifically: adding a graphene or a graphene derivative to the mixed solvent, and after ultrasonic dispersion, adding polyvinyl alcohol under mechanical stirring, at 50 to 120 Stir at ° C until the polyvinyl alcohol is dissolved.
The preparation method according to claim 1 or 4, wherein the mixed solvent is prepared by mixing an organic solvent having a weight ratio of 95:5 to 70:30 and water; and the organic solvent is selected from the group consisting of dimethyl sulfoxide. One or more of ethylene glycol, propylene glycol, glycerin, n-butanol, isobutanol, triethylene glycol, and tetrahydrofuran.
The preparation method according to claim 4, wherein the ultrasonic dispersion is performed for 1 to 6 hours.
The preparation method according to claim 1, wherein the gel spinning is specifically: mixing the graphene or graphene derivative and polyvinyl alcohol in a mixed solvent to obtain a spinning dope, The spinning dope is filtered and defoamed at 80 to 120 ° C, and then ejected through a spinneret into a methanol coagulation bath of -15 to 5 ° C, and the spinning dope is quenched to form nascent fibers.
The preparation method according to claim 7, wherein the defoaming mode is selected from the group consisting of vacuum defoaming and atmospheric degassing; the spinneret has a pore size ranging from 0.06 to 0.15 mm. The number is from 1 to 6000.
The preparation method according to claim 1, wherein the high-exposure stretching is specifically: the nascent fibers obtained by gel spinning are sequentially subjected to extraction, drying, and then subjected to a hot stretching temperature of 120 to 240 ° C. The hot stretching was carried out under the conditions of a draw ratio of 8 to 36 times and a heat setting time of 1 to 15 minutes.
The preparation method according to claim 9, wherein the extraction temperature is 20 to 80 ° C for 2 to 60 minutes, and the extracting agent used is selected from methanol or ethanol; and the drying temperature is 60 to 120 ° C. , drying time is 2 ~ 24h.