KR101538056B1 - Prepartion method of polyurethane composite containing carbon nanotube - Google Patents

Abstract

The present invention relates to a method for producing a carbon nanotube-polyurethane composite and a composite body therefor. According to the present invention, it is possible to manufacture a polyurethane composite in which carbon nanotubes are evenly dispersed in a more simplified manner, and the resulting composite can exhibit improved electrical conductivity and mechanical properties.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a carbon nanotube-containing polyurethane composite,

The present invention relates to a method for producing a polyurethane composite containing carbon nanotubes.

Polyurethane is a polymer which is applied to various industrial fields such as automobile field, electronic material field, clothing field, paint field and the like, and it is required to control various physical properties such as tensile strength, abrasion and elongation depending on the application field.

In general, the physical properties of polymer are controlled by mixing raw materials or mixing functional additives. In recent years, carbon-based materials such as carbon black, carbon nanotubes, and graphene have been combined with polymers, Is being attempted.

Of the above carbon-based materials, particularly carbon nanotubes are typical carbon nanostructures having excellent thermal conductivity, electrical conductivity, and mechanical strength, and are attracting attention as materials applicable to various electric devices and high-strength nanocomposites.

However, since the carbon nanotubes are entangled with each other by a strong van der Waals force, they are not uniformly dispersed in the polymer medium to be complexed. Accordingly, attempts have been made to introduce a functional group onto the surface of a carbon nanotube to modify it, or to apply a multi-step physical process. However, such a method requires a complicated pretreatment process, resulting in a deterioration in productivity. In addition to the use of an organic solvent which is harmful to the human body or the environment, deterioration of the physical properties due to damage of the carbon nanotubes occurs in the pretreatment of the carbon nanotubes And the like.

Korean Registered Patent No. 1182723 (2012.09.07)

The present invention is intended to provide a method for producing a polyurethane composite in which carbon nanotubes are evenly dispersed by a more simplified method.

The present invention also provides a carbon nanotube-polyurethane composite which is produced by the above-described method and has improved electrical conductivity and mechanical properties.

According to the present invention, there is provided a method of manufacturing a carbon nanotube, comprising: preparing a dispersion in which a polyol and a self-aligned carbon nanotube are mixed; And a step of adding a diisocyanate compound to the dispersion in the presence of a chain extender, followed by a polymerization reaction, thereby producing a carbon nanotube-polyurethane composite.

According to the present invention, there is also provided a process for producing a carbon nanotube-polyurethane composite comprising a step of polymerizing a dispersion containing a polyol, a self-aligned carbon nanotube and a diisocyanate compound in the presence of a chain extender do.

According to one embodiment, the dispersion comprises a composition comprising carbon nanotubes self-aligned with a polyol, or a composition comprising a polyol, a self-aligned carbon nanotube and a diisocyanate compound under a bead mill, To < RTI ID = 0.0 > 300 < / RTI >

According to one embodiment, 0.5 to 5 parts by weight of self-aligned carbon nanotubes, 1 to 10 parts by weight of chain extender and 5 to 30 parts by weight of diisocyanate compound may be used per 100 parts by weight of the polyol have.

Also, according to one embodiment, the self-aligned carbon nanotube may include a plurality of carbon nanotubes having a diameter of 5 to 20 nm and a length of 1 to 600 μm.

Further, according to one embodiment, the polyol may have a weight average molecular weight of 500 to 10,000. The polyol may be at least one compound selected from the group consisting of polytetramethylene glycol, polyethylene glycol, polypropylene glycol and polycaprolactone diol.

According to one embodiment, the diisocyanate compound is selected from the group consisting of 1,6-hexamethylene diisocyanate, 4,4'-methylenediphenyl diisocyanate, Isophorone diisocyanate, 4,4'-diisocyanato dicyclohexylmethane, tetramethylene diisocyanate, methylpentamethylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, , Dodecamethylene diisocyanate, 1,4-diisocyanato cyclohexane, 4,4'-diisocyanato dicyclohexylpropane- (2,2) ( 4,4'-diisocyanato dicyclohexylpropane- (2,2)), 1,4-diisocyanato benzene, 2,4-diisocyanato toluene, , 2,6-diisocyanato toluene ( 2,6-diisocyanato toluene, diisocyanato diphenylmethane, tetramethylxylene diisocyanate, p-xylene diisocyanate, and p-isopropylidene And may be at least one compound selected from the group consisting of p-isopropylidene diisocyanate.

According to one embodiment, the chain extender may be at least one compound selected from the group consisting of ethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol.

Meanwhile, the carbon nanotube-polyurethane composite according to an embodiment may have an electric conductivity (S / cm) increased by 10 to 10,000 times compared to a polyurethane mixed with an entangled carbon nanotube have.

In addition, the carbon nanotube-polyurethane composite according to an embodiment may have a tensile strength (kgf / cm2) of 10 to 100% higher than that of a polyurethane combined with an entangled carbon nanotube have.

In addition, the carbon nanotube-polyurethane composite according to an embodiment may have an elongation percentage (%) that is 50 to 400% higher than that of a polyurethane mixed with an entangled carbon nanotube.

According to the present invention, it is possible to manufacture a polyurethane composite in which carbon nanotubes are evenly dispersed in a more simplified manner, and the resulting composite can exhibit improved electrical conductivity and mechanical properties. The carbon nanotube-polyurethane composite can be usefully used in various industrial fields such as automobile field, electronic material field, clothing field, and paint field.

1 is a scanning electron microscope (SEM) image of a carbon nanotube in the form of a self-aligned carbon nanotube (FIG. 1 (a)) and an entangled carbon nanotube (FIG. 1 (b) And the photographs are enlarged and observed.
2 is a graph showing the results of a scanning electron microscope (SEM) of a carbon nanotube-polyurethane composite [FIG. 2 (a)] according to an embodiment of the present invention and a composite according to a comparative example (FIG. 2 (b) And the photographs are enlarged and observed.

Hereinafter, a method for producing a carbon nanotube-polyurethane composite according to specific embodiments of the present invention and a composite body therefor will be described in detail.

Prior to that, and unless explicitly stated throughout the present specification, the terminology is used merely to refer to a specific embodiment and is not intended to limit the present invention. And, the singular forms used herein include plural forms unless the phrases expressly have the opposite meaning. Also, as used herein, the term " comprises " embodies certain features, areas, integers, steps, operations, elements and / or components, It does not exclude the existence or addition of a group.

Meanwhile, the inventors of the present invention have conducted studies on polyurethane composites containing carbon nanotubes (hereinafter, referred to as 'CNTs'), and self-aligned CNTs have been widely used as entangled CNTs , It was confirmed that it exhibited excellent dispersibility to polyurethane even without a separate pretreatment. Accordingly, it is possible to provide a CNT-polyurethane composite having remarkably improved electrical conductivity and mechanical properties by using a more simplified method in which the self-aligned CNT is not required for a separate pretreatment for CNTs. Respectively.

According to this embodiment of the present invention,

Preparing a dispersion in which a polyol and a self-aligned carbon nanotube are mixed; And

Adding a diisocyanate compound to the dispersion in the presence of a chain extender to cause a polymerization reaction

A method of manufacturing a carbon nanotube-polyurethane composite comprising the carbon nanotube-polyurethane composite is provided.

Hereinafter, each step included in the manufacturing method will be described in detail.

First, a method of manufacturing a CNT-polyurethane composite according to an embodiment may include preparing a dispersion in which a polyol and self-aligned CNTs are mixed.

The polyol is a compound having an equivalent number of hydroxyl groups per molecule of 2 or more, and forms a urethane bond by reaction with an isocyanate compound. In the present invention, the polyol may be a conventional compound used for forming a polyurethane without any particular limitation. However, as a non-limiting example, the polyol may be at least one compound selected from the group consisting of polytetramethylene glycol, polyethylene glycol, polypropylene glycol, and polycaprolactone diol. In order to secure the mechanical properties required of the polyurethane, it is advantageous that the weight average molecular weight of the polyol is 500 to 10,000, or 1,000 to 5,000, or 1,000 to 4,000, or 1,500 to 3,500, or 2,000 to 3,500.

On the other hand, as shown in Fig. 1, the self-aligned CNTs (Fig. 1 (a)), unlike general CNTs having an entangled structure (Fig. 1 (b) And a plurality of self-aligned CNTs having a diameter of several to several hundreds of micrometers in scale. Accordingly, when the self-aligned CNTs are mixed with a polyol (medium), a plurality of bundles of CNTs can be uniformly dispersed in the polyol in a loosened form. However, the CNTs with an entangled structure are separated by the strong van der Waals force between the CNTs to form agglomerates, whereas the self-aligned CNTs are subjected to separate pretreatment (for example, , A method of introducing a functional group onto the surface of CNT) or a multi-step physical dispersion method, etc., it is possible to provide a composite having more uniform and improved electrical, mechanical and thermal properties.

The self-aligned CNTs may be conventional ones having a plurality of CNTs arranged in a bundle shape. The structures of single walled carbon nanotubes (CNTs) and multiwalled carbon nanotubes (CNTs) It is not limited. However, according to one embodiment, the self-aligned CNT includes a plurality of carbon nanotubes having a diameter of 5 to 20 nm and a length of 1 to 600 μm, Can be more advantageous.

Meanwhile, according to one embodiment, the dispersion in which the polyol and the self-aligned CNT are mixed may be milled for 30 to 300 minutes, or 30 to 120 minutes, or 30 to 90 minutes, or 30 to 60 minutes ≪ / RTI > for a while. That is, although the self-aligned CNTs may have a limited dispersion in a uniform dispersion state by a general mixing process, a dispersion having an excellent dispersibility relative to a CNT having a tangled structure may be prepared by applying the optimal dispersion method as in the embodiment .

In this case, the self-aligned CNT may be included in an amount of 0.5 to 5 parts by weight, or 0.5 to 3.5 parts by weight, or 1 to 3.5 parts by weight, or 1 to 3 parts by weight, based on 100 parts by weight of the polyol. That is, it is advantageous that the self-aligned CNT is contained in an amount of 0.5 part by weight or more based on 100 parts by weight of the polyol in order to sufficiently exhibit the effect of improving the physical properties required in the present invention. However, when the CNT is added in an excessive amount, the dispersed state of the CNT becomes poor, so that CNT agglomerates may be formed in the composite, thereby deteriorating the mechanical properties of the composite. Accordingly, it is advantageous that the self-aligned CNT is included in an amount of 5 parts by weight or less based on 100 parts by weight of the polyol.

If necessary, the dispersion may further contain a hydrocarbon-based diluent. The hydrocarbon diluent may be an aliphatic hydrocarbon or aromatic hydrocarbon having 6 to 10 carbon atoms, or a mixture thereof, for adjusting the viscosity of the composite to optimize workability according to application fields. The hydrocarbon diluent may be included in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the polyol.

Meanwhile, the method for producing a CNT-polyurethane composite according to an embodiment may include a step of adding a diisocyanate compound to the dispersion in the presence of a chain extender to cause a polymerization reaction.

That is, the process for producing a CNT-polyurethane composite according to the present invention can be carried out according to a conventional method for producing a polyurethane, except that the self-aligned CNT is dispersed.

According to one embodiment, the diisocyanate compound is a compound which forms a urethane bond by reaction with the polyol, and a typical compound used for forming the polyurethane can be applied without particular limitation. However, as a non-limiting example, the diisocyanate compound may be selected from the group consisting of 1,6-hexamethylene diisocyanate, 4,4'-methylenediphenyl diisocyanate, But are not limited to, isophorone diisocyanate, 4,4'-diisocyanato dicyclohexylmethane, tetramethylene diisocyanate, methylpentamethylene diisocyanate, Dodecamethylene diisocyanate, 1,4-diisocyanato cyclohexane, 4,4'-diisocyanatodicyclohexylpropane- (2,2) (4) diisocyanatocyclohexane, , 4'-diisocyanato dicyclohexylpropane- (2,2)), 1,4-diisocyanato benzene, 2,4-diisocyanato toluene, 2,6-diisocyanatotoluene (2,6-diiso cyanato toluene, diisocyanato diphenylmethane, tetramethylxylene diisocyanate, p-xylene diisocyanate, and p-isopropylidene diisocyanate (p -isopropylidene diisocyanate) may be used.

At this time, the content of the diisocyanate compound can be determined in consideration of the equivalent ratio with the polyol, the physical properties of the polyurethane to be obtained, and the like, so that the content is not particularly limited. However, according to one embodiment, it is sufficient that the diisocyanate compound is contained in an amount of 5 to 30 parts by weight, or 15 to 30 parts by weight, or 20 to 30 parts by weight, or 25 to 30 parts by weight, based on 100 parts by weight of the polyol It may be advantageous in securing physical properties.

The chain extender may also be a conventional compound used for forming a polyurethane without any particular limitation. However, as a non-limiting example, it may be at least one compound selected from the group consisting of ethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol.

The content of the chain extender is not particularly limited as it can be determined in consideration of the physical properties of the polyurethane to be finally formed. However, according to one embodiment, the chain extender may be included in an amount of 1 to 10 parts by weight, or 5 to 10 parts by weight, based on 100 parts by weight of the polyol.

For the polymerization reaction, organic solvents such as dimethylformamide, methyl ethyl ketone, methyl isobutyl ketone, xylene, toluene and 1-methyl-2-pyrrolidone may be used. At this time, it is preferable that the organic solvent does not contain moisture. If water is contained in the organic solvent, water reacts with isocyanate groups to generate carbon dioxide, thereby forming an unintended foam-like complex. According to one embodiment, the organic solvent may be included in 100 to 500 parts by weight, or 200 to 500 parts by weight, or 200 to 400 parts by weight, or 200 to 300 parts by weight, based on 100 parts by weight of the polyol. That is, when the content of the organic solvent is small, sufficient viscosity can not be secured and stirring may be difficult. If the content of the organic solvent is excessive, the drying time may be long and the process efficiency may be decreased.

The complex obtained through the polymerization reaction may contain an unreacted isocyanate group. In order to remove the unreacted isocyanate group, a step of adding a compound such as dibutylamine and post-treating may be further performed.

Meanwhile, according to another embodiment of the present invention,

Polyol, a self-aligned carbon nanotube and a diisocyanate compound in the presence of a chain extender

A method of manufacturing a carbon nanotube-polyurethane composite comprising the carbon nanotube-polyurethane composite is provided.

That is, the method for producing a composite according to the present invention may be carried out by i) preparing a dispersion in which a polyol and a self-aligned CNT are mixed separately as in the above-described embodiment, and adding a diisocyanate compound thereto to perform a polymerization reaction . Then, the method for producing the composite according to the present invention may be carried out by a method in which ii) a polymerization reaction is carried out while mixing a polyol, a self-aligned CNT, and a diisocyanate compound.

Here, the dispersion may be prepared by mixing a composition containing a polyol, a self-aligned carbon nanotube and a diisocyanate compound, for 30 to 300 minutes under a bead mill, as described above.

The description of the polyol, the self-aligned CNT, the diisocyanate compound, the chain extender and the like is replaced with the above description.

Meanwhile, according to another embodiment of the present invention, there is provided a CNT-polyurethane composite comprising a polyurethane and CNT dispersed in the polyurethane.

The composite is a composite in which CNTs are uniformly dispersed in a matrix containing polyurethane, and is produced according to the method described above. As described above, since the self-aligned CNT is used in the method of producing the composite, a composite having excellent electrical, mechanical, and thermal properties can be provided, because the dispersibility of the CNT is excellent.

According to one embodiment, the CNT-polyurethane composites prepared by the above-described method have a tensile strength of about 10 to 10,000 times, or about 50 to 10,000 times, 70 to 10,000 times, or 70 to 9,600 times.

And, according to one embodiment, the CNT-polyurethane composites prepared by the above-mentioned method can be used in an amount of about 10 to 100%, or about 15 to 30% , Or a tensile strength (kgf / cm2) improved by 15 to 25%.

Furthermore, the CNT-polyurethane composites prepared by the above-mentioned method can exhibit an excellent elongation with an improved tensile strength. That is, according to one embodiment, the CNT-polyurethane composites produced by the above-described method can be used in an amount of about 50 to 400%, or about 100 to 200%, relative to the complexed polyurethane, , Or an elongation (%) improved by 100 to 150%.

In particular, the CNT-polyurethane composites prepared by the above-mentioned method can maintain effective initial properties even after being stored in a harsh environment, as the CNTs include improved dispersion. According to one embodiment, when the CNT-polyurethane composite is stored at about 80 ° C for 2 weeks, tensile strength and elongation are measured. When the measured tensile strength and elongation are 80% or more or 90% or more Lt; / RTI >

However, the physical properties of the CNT-polyurethane composite may vary depending on the structure, type, and molecular weight of the polyurethane, which is a medium, and those skilled in the art will appreciate that the properties of the composite You will be able to control it.

Such CNT-polyurethane composites of the present invention can be usefully used in various industrial fields such as automobile field, electronic material field, clothing field, and paint field.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments are described to facilitate understanding of the present invention. However, the following examples are intended to illustrate the present invention without limiting it thereto.

Example  One

A composition comprising about 2% by weight of self-aligned CNT (manufacturer: Hanwha Chemical, CM-250) and about 98% by weight of polyol (polypropylene glycol, weight average molecular weight about 3,000) , bead 0.8Φ) for about 60 minutes to prepare a dispersion.

Then, about 80 g of the above dispersion, about 5 g of 1,4-butanediol, about 20 g of an aliphatic diisocyanate (1,6-hexamethylene diisocyanate) and about 200 g of dimethylformamide were fed into the reactor, For about 1 hour, and then dried at about 70 캜 for about 24 hours to obtain a carbon nanotube-polyurethane composite.

Example  2

About 3 weight percent of self-aligned CNT (manufacturer: Hanwha Chemical, product name: CM-250), about 94 weight percent polyol (polypropylene glycol, weight average molecular weight about 3,000), and about 3 weight percent hydrocarbon diluent An aliphatic hydrocarbon mixture having 6 to 10 carbon atoms) was mixed with bead mill (bead 0.8?) For about 60 minutes to prepare a dispersion.

Then, about 80 g of the above dispersion, about 5 g of 1,4-butanediol and about 20 g of an aliphatic diisocyanate (1,6-hexamethylene diisocyanate) were added to the reactor, and the mixture was stirred at room temperature for about 1 hour , And dried at about 70 DEG C for about 24 hours to obtain a carbon nanotube-polyurethane composite.

Example  3

About 78 g polyol (polypropylene glycol, weight average molecular weight about 3,000), about 5 g 1,4-butanediol, about 20 g aliphatic diisocyanate (1,6-hexamethylene diisocyanate), about 200 g dimethyl form Amide, and about 2 g of self-aligned CNT (manufacturer: Hanwha Chemical, CM-250) was mixed with bead mill (bead 0.8Φ) for about 60 minutes. Then, the mixture was stirred at room temperature for about 1 hour, and then dried at about 70 ° C for about 24 hours to obtain a carbon nanotube-polyurethane composite.

Comparative Example

A carbon nanotube-polyurethane composite was obtained in the same manner as in Example 1, except that CNT (manufactured by Hanwha Chemical Co., Ltd., product name: CM-95) having an entangled structure was used instead of the self-aligned CNT.

Test Example  1 (observation of dispersion state of carbon nanotubes)

The surface of each composite obtained in Example 1 and Comparative Example was observed using a scanning electron microscope (SEM). The results are shown in Fig.

2, it was confirmed that the carbon nanotubes were uniformly dispersed in the composite according to Example 1 (FIG. 2 (a)). On the other hand, it was confirmed that the carbon nanotubes were not evenly dispersed in the composite according to the comparative example (Fig. 2 (b)).

Test Example  2 (Measurement of electrical conductivity and mechanical properties)

The electrical conductivity and the mechanical properties of each of the composites obtained in Examples and Comparative Examples were measured in the following manner, and the results are shown in Table 1 below.

1) Electrical Conductivity (S / cm): The resistance of the composite was measured using LORESTA equipment according to JIS-K6911 standard, and the electrical conductivity was measured by measuring the specimen of the composite

2) Tensile strength (kgf / cm2) and elongation (%): 10 specimens of Type I standard of ASTM D638 were prepared. The initial tensile strength and elongation of five specimens were measured using a universal testing machine. The remaining five specimens were stored at about 80 ° C. for two weeks, and then tensile strength and elongation were measured in the same manner.

Electrical conductivity
(S / cm) Tensile strength (kgf / cm2) Elongation (%) Early After 2 weeks at 80 ℃ Early After 2 weeks at 80 ℃ Example 1 4.5 × 10 ^-4 69 65 720 680 Example 2 3.5 × 10 ^-2 72 68 680 640 Example 3 5.9 x 10 ^-2 70 67 690 650 Comparative Example 6.2 × 10 ^-6 58 25 580 450

 As can be seen from the above Table 1, the composites according to Examples 1 to 3 were found to have electrical conductivity increased by about 70 to 9500 times as compared with the composites of the comparative examples. Further, it was confirmed that the composite according to Examples 1 to 3 exhibited a tensile strength increased by about 18% to 25%, and an initial elongation improved by about 100 to 140%, compared with the composite of Comparative Example. As described above, it was confirmed that the composites of the examples prepared using the self-aligned CNTs had remarkably improved electrical and mechanical properties as compared with the composites of the comparative examples prepared using the CNTs with the tangled structure.

Also, it was confirmed that the composite according to Examples 1 to 3 was able to maintain a level of about 94% or more as compared with initial physical properties even after being stored in a harsh environment, and maintained about 80% of the initial physical properties for about 4 weeks or more.

Claims (13)

Preparing a dispersion in which a polyol and a self-aligned carbon nanotube are mixed; And
Adding a diisocyanate compound to the dispersion in the presence of a chain extender to cause a polymerization reaction,
(S / cm), 10 to 100% increased tensile strength (kgf / cm < 2 >), and a tensile strength in the range of 50 to 400 % ≪ / RTI > increased elongation (%) of the carbon nanotube-polyurethane composite.
Polymerizing a dispersion comprising a polyol, a self-aligned carbon nanotube and a diisocyanate compound in the presence of a chain extender,
(S / cm), 10 to 100% increased tensile strength (kgf / cm < 2 >), and a tensile strength in the range of 50 to 400 % ≪ / RTI > increased elongation (%) of the carbon nanotube-polyurethane composite.
3. The method according to claim 1 or 2,
The dispersion may be prepared by mixing a composition comprising carbon nanotubes self-aligned with a polyol, or a composition comprising a polyol, a self-aligned carbon nanotube and a diisocyanate compound for 30 to 300 minutes under a bead mill, Wherein the carbon nanotube-polyurethane composite is produced by a method comprising the steps of:
3. The method according to claim 1 or 2,
A carbon nanotube-polyurethane composite in which 0.5 to 5 parts by weight of self-aligned carbon nanotubes, 1 to 10 parts by weight of a chain extender, and 5 to 30 parts by weight of a diisocyanate compound are used relative to 100 parts by weight of the polyol Gt;
3. The method according to claim 1 or 2,
Wherein the self-aligned carbon nanotube comprises a plurality of carbon nanotubes having a diameter of 5 to 20 nm and a length of 1 to 600 탆.
3. The method according to claim 1 or 2,
Wherein the polyol has a weight average molecular weight of 500 to 10,000.
3. The method according to claim 1 or 2,
Wherein the polyol is at least one compound selected from the group consisting of polytetramethylene glycol, polyethylene glycol, polypropylene glycol and polycaprolactone diol.
3. The method according to claim 1 or 2,
The diisocyanate compound is preferably selected from the group consisting of 1,6-hexamethylene diisocyanate, 4,4'-methylenediphenyl diisocyanate, isophorone diisocyanate, , 4,4'-diisocyanato dicyclohexylmethane, tetramethylene diisocyanate, methylpentamethylene diisocyanate, dodecamethylene diisocyanate, dodecamethylene diisocyanate, diisocyanate, 1,4-diisocyanato cyclohexane, 4,4'-diisocyanato dicyclohexylpropane- (2,2) (4,4'-diisocyanato dicyclohexylpropane- (2,2)), 1,4-diisocyanato benzene, 2,4-diisocyanato toluene, 2,6-diisocyanate 2,6-diisocyanato toluene, diisocyanine And is composed of diisocyanato diphenylmethane, tetramethylxylene diisocyanate, p-xylene diisocyanate, and p-isopropylidene diisocyanate. Wherein the carbon nanotube-polyurethane composite is at least one compound selected from the group consisting of carbon nanotubes.
3. The method according to claim 1 or 2,
Wherein the chain extender is at least one compound selected from the group consisting of ethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol.
delete delete delete A carbon nanotube-polyurethane composite produced by the method according to claim 1 or 2.

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