FIELD OF THE INVENTION

00001. The present invention relates to methodology of formation of CNT yarn
by spinning and twisting or more particularly the present disclosure relates to a
spinning and twisting system with a better true-twist for preparing pristine or
composite carbon nanotube yarn which is twisted either dry or with liquid.
BACKGROUND OF THE INVENTION
2. Fabrics/textiles (technical or general) are an essential and integral part of daily life. The primary yarn material, required for preparing fabrics/textiles has been around for over a few centuries. The yarn is prepared by the spinning of different types of fibers (cotton, polymers, silk) into a continuous length entity and spinning is a fundamental and primary process. The object of spinning is to transform the single fibers into a cohesive and workable continuous length yarn. Spinning involves stretching the yarn to the required tex (unit of weight used to measure the density of yarns, equals to 1 gram per 1000 meters) giving the thread strength by adding a twist and winding on to a bobbin. Throughout the world, the various technical or general fabric is prepared from either natural or synthetic yarns. The two classes of the spinning process developed by humans are manual and machine spinning. Before the industrial revolution, hand spinning method was widely used, and after the industrial revolution, many developments were achieved by the textile industry to ease the process of spinning by machinery. Using machinery led to a consistent and effective spinning process with reduced time.
3. Various techniques are used to manufacture yarn either manually or using machinery. Irrespective of the technique utilized in the yarn manufacturing, the twist is an important parameter. Twist helps the constituent fibers of the yarn to stay together and helps in achieving the desired properties. The change in the level of twist changes several yarn properties including

strength and softness. Without twist, the fibers would become weak and are of no practical use. The twist is of two types, true and false. In the case of true-twist, one end of the yarn is rotated relative to the other end. This type of twist is observed in spun yarns. In the case of false-twist, both ends of the yarn are clamped by rollers and twist is inserted with a false twister between the clamping points. The twist is expressed as the number of turns per unit length of yarn, and conventional units include turns per inch (TPI), turns per meter (TPM), and so on.
4. Utilizing spinning to convert nanomaterials such as carbon nanotubes into macro-structure including yarn is an exciting idea. Pristine CNTs have the best properties, but at, i.e., relatively short lengths of few microns CNT have limited industrial applications. Hence, converting the CNT into macro-structure like yarn and later to mats/cloth/textiles will be beneficial for several industries. These textiles have numerous potential applications, such as the ability to conduct energy, protect the wearer from hazards, and so on. Further, conversion into macro formats can make CNT relatively safe to handle and process in commercial, industrial, and military applications. The primary driving force for the conversion of CNTs into macro form is the lightweight (1/5th of copper), inert and non-corrosive, less thermal build up and no fatigue failure nature of the CNT yarn and mats. Several strategies have been developed to prepare CNT fiber and mats. The fiber preparation method includes dry and wet spinning. In the dry spinning process, carbon nanotube arrays grown on a substrate is converted into yarn. In wet spinning process nanotubes solution is converted to yarn. The only method which is capable of preparing the yarn and mat is the gas phase pyrolysis (floating catalyst) method. It holds high promise for large-scale commercialization of CNT yarn and mat. In the gas phase pyrolysis method CNT sock or aerogel is generated and converted to either yarn or mat.
5. Several inventors have disclosed methods to spin CNT into yarn, the disclosures are novel and are capable of producing CNT yarn. Some of the most relevant disclosures related to the present invention are CN102953171A and US 2018/0171512 Al which discloses the spinning of CNT yarn with a false twist.

The disclosures as mentioned above involve the provision of false twisting, and the constraints of the false twisting concept remain, and loss in yarn throughput is considered cost prohibitive. Instead, if a spinner can produce or create a real twist effectively a yarn with relatively low porosity and mechanical strength either by dry or wet spinning is desired.

00007. But the conventional methods often comprises of some drawback as
they fail to provide the CNT yarn with low porosity yet higher mechanical
strength. The present invention meets the long felt need.
OBJECTS OF THE INVENTION
8. It is therefore the primary object of the present invention to provide a spinning method of carbon nanotube yarn in true-twist mechanism with relatively low porosity and enhanced mechanical strength.
9. Another object of the present invention is to provide a spinning method of carbon nanotube yarn, which includes low rotation speed and thereby reduces in equipment cost yet effective.
10. Yet another object of the present invention is to provide a spinning method of carbon nanotube yarn, which includes benefit of load transfer and enhancement of mechanical strength.

SUMMARY OF THE INVENTION
000011. One or more drawbacks of conventional systems and process for a
method of preparing of composite carbon nanotube (CNT) yarn by spinning and
twisting are overcome, and additional advantages are provided through the
composition as claimed in the present disclosure. Additional features and
advantages are realized through the technicalities of the present disclosure. Other
embodiments and aspects of the disclosure are described in details herein and
are considered to be part of the claimed disclosure.
000012. A method for preparing of composite carbon nanotube (CNT) comprises
the steps of :
i) preparation of array of CNT in the form of an inter-connected web (5, 5a); ii) employing true-twist spinning process with a relatively less distance
between the CNT web and the other end (between 5 and 7), where bobbin collecting the CNT yarn acts as a collector and twisting element; iii) spinning of CNT wire either dry or with wetting liquid; iv) after inpigning with wetting liquid, the CNT wire is rotated with an
appropriate speed, which leads to formation of entangled and densified CNT metal nanowire composite; v) heating of CNT metal nanowire in a controlled atmosphere particularly with laser to enhance the mechanical strength and improved interfacial connectivity between the CNT and metal nanowires; vi) evaporation of liquid during laser processing to draw the adjacent
nanotubes together for enhancing the load transfer and mechanical strength; vii) further heat treatment or annealing in high vacuum (10-6 to 10-7 Torr) and at high temperature of 800-1000°C in inert atmosphere in presence of Hydrogen (H2) and Argon (Ar); viii) conversion of annealed CNT yarn to woven CNT cloth.

13. Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, alongwith the accompanying drawing figures.
14. It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
15. The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
000016. The illustrated embodiments of the subject matter will be best
understood by reference to the drawings, wherein like parts are designated by
like numerals throughout. The following description is intended only by way of
example, and simply illustrates certain selected embodiments of devices,
systems, and processes that are consistent with the subject matter as claimed
herein, wherein:
17. Figure 1 showing the Schematic of spinner with better true-twist.
18. Figure 2 showing the spinning of wet spun carbon nanotube-
metal nanowire (Copper/ Silver/ Nickel) yarn, where CNT is synthesized by LPCVD on catalyst coated substrate.
19. Figure 3 showing the Scanning electron microscope (SEM) image of CNT web.
20. Figure 4 showing the SEM image of untwisted as pulled CNT yarn.
21. Figure 5 showing the SEM image of dry twisted CNT yarn with better true-twist.

22. Figure 6 showing the SEM image of liquid twisted CNT yarn with better true-twist.
23. Figure 7 showing the SEM image of Ag nanowire liquid twisted CNT yarn with better true-twist, laser processed and annealed.
000024. Figure 8 showing the SEM image of manually woven CNT cloth from
true-twisted CNT yarn.
000025. The figures depict embodiments of the disclosure for purposes of
illustration only. One skilled in the art will readily recognize from the following
description that alternative embodiments of the methods illustrated herein may
be employed without departing from the principles of the disclosure described
herein.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
26. While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents and alternative falling within the scope of the disclosure.
27. It is to be noted that a person skilled in the art would be motivated from the present disclosure to arrive at a method of fabrication of impeller with complex blade. However, such modifications should be construed within the scope of the disclosure. Accordingly, the drawings illustrate only those specific details that are pertinent to understand the embodiments of the present disclosure, so as not to obscure the disclosure with details that will be clear to those of ordinary skill in the art having benefit of the description herein.
28. As used in the description herein and throughout the claims that follow, the meaning of “a”, “an”, and “the” includes plural reference unless the context

clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
29. The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a method, system, assembly, spinning, twist, yarn, nanotube that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such method, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises…..a “does not, without more constraints, preclude the existence of other elements or additional elements in the system, apparatus or device.
30. The present invention relates to a true-twist spinning process for spinning and twisting for preparing of pristine or composite carbon nanotube (CNT) yarn through true-twist spinning process.
31. Spinning arrays of carbon nanotube (CNT) grown on a substrate into CNT yarn is an essential and unique technique to form CNT yarn for various applications. The vital parameters in achieving yarn with significant mechanical strength (few 100’s MPa to few GPa, for the practical purpose the breaking strength, i.e. magnitude of load should be in few lbs) are the type of twist, twisting angle, densification, and post-processing.
32. The process comprises the steps of:
i) preparation of array of carbon nanotube (CNT) in the form of an inter-connected web (5, 5a); ii) employing true-twist spinning process with a relatively less distance
between the CNT web and the other end (between 5 and 7), where bobbin collecting the CNT yarn acts as a collector and twisting element; iii) spinning of CNT wire either dry or with wetting liquid; iv) after inpigning with wetting liquid, the CNT wire is rotated with an
appropriate speed, which leads to formation of entangled and densified CNT metal nanowire composite;

v) heating of CNT metal nanowire in a controlled atmosphere particularly with laser to enhance the mechanical strength and improved interfacial connectivity between the CNT and metal nanowires; vi) evaporation of liquid during laser processing to draw the adjacent nanotubes together for enhancing the load transfer and mechanical strength; vii) further heat treatment or annealing in high vacuum (10-6 to 10-7 Torr) and at high temperature of 800-1000°C in inert atmosphere in in presence of Hydrogen (H2) and Argon (Ar); viii) conversion of annealed CNT yarn to woven CNT cloth.
33. The heating of CNT wire or the laser processing of CNT wire is performed with laser in a vacuum atmosphere in presence of inert gas at high vacuum (>10-6 Torr or 10-6 – 10-7 Torr) to avoid oxidation of carbon nanotube (CNT) and also aids in removal of any de-absorbed species during laser heating.
34. The laser is scanned across the length of CNT yarn. The high thermal conductivity of the nanotubes results in uniform heating, melting/welding of metal nanowires and connecting the adjacent nanotubes and benefit in load transfer and in enhancing mechanical strength. Further, during evaporation of the liquids (while laser processing) a sizeable capillary force may be generated to draw adjacent nanotubes together.
000035. The rotation of the CNT yarn occurs in the true-twist mechanism is at a
speed <1000 RPM (10-10000 RPM) which is significantly less than 5000-10000
rpm utilized in traditional true-twisters. The advantages of the low rotational
speed include the reduction in equipment cost and hence lower cost for yarn
production. Besides, the modified true-twist disclosed here can produce either
dry or liquid twisted CNT yarn.
000036. The liquid twisting includes a nanowire infiltration into carbon
nanotube yarn. The liquids are used in this purpose are, but not limited to
isopropyl alcohol, ethanol, acetone, ethylene glycol.

37. This liquid comprises metal nanowire made up of Cu/Ni/Ag nanowire with dimensions of length 10-50 microns and diameter 10-20nm. The metal nanowire dispersions are prepared, but not limited to silver, copper and nickel in liquids that have good wettability with CNT. The volume percentage of metal nanowire is 10-80% in liquid.
38. Infiltration by CNT wetting liquid is an efficient method to improve mechanical strength by densifying CNT wire/fiber prepared by spinning from an aligned array of CNT. Infiltration of the metal nanowire into the CNT volume improves interfacial connectivity between the adjacent CNT and further incorporating metal nanowires at CNT junctions will enhance mechanical stability. The tensile strength of yarns prepared by spinning is limited to the Van der Waals forces and weak interfacial interactions among the CNT. However, the yarn specific strength is higher due to the tube alignment and entanglement generated in the spinning or condensing process. Whereas the limitation, i.e., tensile strength beyond specific value resides in weak inter tube shear interactions. Hence increasing strength is necessary for various applications. And the inclusion of metal nanowires into CNT wires/fibers can benefit in connecting the adjacent CNT and help in load transfer and in enhancing mechanical strength. Hence the disclosed true-twist liquid twist process can result in improving the mechanical strength.
39. The carbon nanotube used for this purpose comprises single-walled, double walled and multiwalled carbon nanotubes.
40. The metal nanowire dispersed liquid is infiltrated before the yarn is twisted, wherein the width of the metal nanowire dispersed liquid jet is defined by the width of the CNT web.
000041. The location of the metal nanowire dispersed liquid jet is defined by
distance of the CNT web and the twist and collector bobbin and the velocity/speed
of the metal nanowire dispersed liquid jet on to CNT web is dependent on the
speed of collector spindle.

42. The CNT is processed with laser of varying power dependent on diameter of CNT metal nanowire composite. The laser can be of but not limited to CO2, diode laser.
43. The laser processing is either performed in high vacuum (>10-6 Torr0 and in presence of inert gases such as Ar, H2, O2 and N2.
44. The laser scan speed can be but not limited to 1 to 10 mm/sec.
45. The metal nanowire infiltrated CNT is processed at high temperature i. e. 800 - 1000°C and at high vacuum.
46. In accordance with another embodiment of the present invention, there is provided a spinning machine with better true-twist comprises:

- a height and anchoring points distance adjustable mechanism for holding CNT array substrate;
- a twisting and collecting bobbin with adjustable speed to form twist angle variable CNT yarn of variable diameter;
- a nanomaterial dispersed CNT wetting liquid jetting mechanism to condense CNT yarn.
000047. The twisting can be of two types, true-twist and false twist. In the case
of true-twist, one end of the yarn is rotated relative to the other end. This type of
twist is observed in spun yarns. In the case of false-twist, both ends of the yarn
are clamped by rollers and twist is inserted with a false twister between the
clamping points. The twist is expressed as the number of turns per unit length of
yarn, and conventional units include turns per inch (TPI), turns per meter (TPM),
and so on. A false twist is applied by clamping both ends of the yarn, usually by
rollers, and the twist is inserted with a false twister between the clamping points.
If the yarn does not traverse along its axis, then the twist will be in opposite
directions, i.e., above and below the false twister. False twisting is a significant
phenomenon, which has considerable practical implications in yarn technology.
As with any process, some constraints in false twisting concept remain, and loss
in yarn throughput is considered cost prohibitive. The present invention relates
to a true-twist spinning process.

000048. Different examples are provided for the true-twisting process of carbon
nanotube (CNT) yarn.
EXAMPLE 1
000049. Process for preparing a true-twisted CNT yarn is described. CNT are
synthesized on a catalyst coated substrate in low-pressure chemical vapor
deposition (LPCVD). The substrate containing aligned CNT array (5, 5a) grown by
LPCVD is transferred to a substrate holder of the true-twisting machine, and
spinning (7) is performed. In this example, the distance between two anchoring
points, i.e., the CNT web and twisting (1) a collecting bobbin (3) is maintained at
80-100 mm. The speed of the collection bobbin is controlled by a small stepper
motor (2). In this example, the speed is ~10 RPM. The speed of the twister is ~700-
1000 RPM. The dry densified twisted CNT (5) achieved better compaction due to
the better true-twist, i.e., reducing the distance between the two anchoring points
resulted in better compaction with a twisting angle of 15-20◦. Further, the CNT is
also densified with CNT wetting liquid having silver nanowire. The silver
(nickel/copper) nanowires are acquired from National Chemical Laboratory,
Pune, India and are dispersed in ethanol as per required volume/weight
percentage. The silver nanowire dispersed in ethanol is sprayed in the form a
stream with controlled velocity. The metal nanowire-dispersed solution sprayed
on to the CNT web just before the web is twisted and transformed into CNT
wire/fiber (10) is used to infuse the CNT. Insertion/inclusion of the metal
nanowires before spinning ensures the presence of metal nanowires between the
sidewall–sidewall contact of adjoining CNTs. Optimization of silver nanowire
infusion into CNT is performed by with silver nanowire of varying volume
percentage in ethanol. Optimal value is determined by the measured mechanical
of the CNT-metal nanowire composite. CNT wire infused with metal nanowire is
collected on the bobbin (3), which is later transferred into a vacuum chamber for
laser processing. The CNT-metal nanowire composite (11) is prepared by heating
the CNT (diameter: 15-50 µm) infused with silver nanowire with a diode laser
(beam size ~20-50 µm) in a vacuum. The power of the laser is varied from 100-
400 W. Laser processing is done in a high vacuum of 10-6 Torr and also in the
presence of Argon. Argon gas of ~500 sccm is used during the laser processing.

Further, the outlet of the vacuum chamber is connected to a vacuum pump which evacuates the Argon gas continuously. The true twisted CNT yarn is converted into a cloth (12) by manual weaving.
EXAMPLE 2
50. In this example, the speed of the collection bobbin controlled by a stepper motor (2) is maintained at ~20 RPM. Changing the speed of the stepper motor to 20 RPM resulted in a twisting angle of 20-30◦. The CNT-metal nanowire composite yarn produced in this example is annealed after laser processing. The annealing of CNT-silver nanowire composite is performed in high temperature (800-1000◦C) and high vacuum (>10-6 Torr) or the presence of Ar, H2 or N2 atmosphere. The bobbin having the CNT- silver nanowire composite that is laser processed is placed inside a three-zone tube furnace, and annealing is performed in steps either in a vacuum or in Ar, H2 or N2 atmosphere for ~8-10 Hrs. The heating/annealing of the composite is performed to enhance further the interface between metal nanowire CNT junctions resulting in enhanced mechanical strength.
51. Although various embodiments of this invention have been shown and described, it should be understood that various modifications and substitutions, as well arrangements and combinations of the preceding embodiments can be made by those skilled in the art, without departing from novel spirit and scope of the invention.
52. The laser processing is either performed in high vacuum (>106 Torr) or in presence of gasses including and not limited to Ar, H2, O2, N2The speed of laser in Claim-II, wherein the laser scan speed can be and not limited to 1-10 mm/sec. The CNT metal nanowire composite in Claim-II, where metal nanowire infiltrated CNT is processed at high temperature (800-1000C) and high vacuum (>10-6 Torr).
000053. Each of the appended claims defines a separate invention, which for
infringement purposes is recognized as including equivalents to the various
elements or limitations specified in the claims. Depending on the context, all

references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
54. Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
55. The present disclosure provides a method of preparing of composite carbon nanotube (CNT) yarn by spinning and twisting.
Equivalents:
000056. With respect to the use of substantially any plural and/or singular
terms herein, those having skill in the art can translate from the plural to the
singular and/or from the singular to the plural as is appropriate to the context
and/or application. The various singular/plural permutations may be expressly
set forth herein for sake of clarity.
000057. It will be understood by those within the art that, in general, terms
used herein, and especially in the appended claims (e.g., bodies of the appended
claims) are generally intended as “open” terms (e.g., the term “including” should
be interpreted as “including but not limited to”, the term “having” should be
interpreted as “having at least”, the term “includes” should be interpreted as
“includes but is not limited to”, etc.). It will be further understood by those within
the art that if a specific number of an introduced claim recitation is intended,
such an intent will be explicitly recited in the claim, and in the absence of such
recitation no such intent is present. For example, as an aid to understanding, the
following appended claims may contain usage of the introductory phrases “at

least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, eve it a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations”, without other modifiers, typically means at least two recitations, or two or more recitations).
58. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
59. The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
60. While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

WE CLAIM :

1. A method for preparing of composite carbon nanotube (CNT) comprises the
steps of :
i) preparation of array of CNT in the form of an inter-connected web (5, 5a); ii) employing true-twist spinning process with a relatively less distance between the CNT web and the other end (between 5 and
7), where bobbin collecting the CNT yarn acts as a collector and twisting element; iii) spinning of CNT wire either dry or with wetting liquid; iv) after inpigning with wetting liquid, the CNT wire is rotated with an
appropriate speed which leads to formation of entangled and densified CNT metal nanowire composite; v) heating of CNT metal nanowire in a controlled atmosphere particularly with laser to enhance the mechanical strength and improved interfacial connectivity between the CNT and metal nanowires; vi) evaporation of liquid during laser processing to draw the adjacent
nanotubes together for enhancing the load transfer and mechanical strength; vii) further heat treatment or annealing in high vacuum and at high temperature in inert atmosphere; viii) conversion of annealed CNT yarn to woven CNT cloth.
2. The method for preparing of composite carbon nanotube (CNT) as claimed in claim 1, wherein the rotational speed of the twist of carbon nanotube (CNT) yarn is 10 – 10000 RPM.
3. The method for preparing of composite carbon nanotube (CNT) as claimed in claim 1, wherein the liquid spinning of carbon nanotube (CNT) yarn comprises metal nanowire dispersion in the wetting liquid with dimension such as length of 10 – 50 micron and has diameter of 10 – 20 nm.

4. The method for preparing of composite carbon nanotube (CNT) as claimed in claim 1, wherein the wetting liquids are selected from isopropyl alcohol, ethanol, acetone and ethylene glycol.
5. The method for preparing of composite carbon nanotube (CNT) as claimed in claim 1, wherein the carbon nanotube (CNT) wetting liquid has 10-80% volume percentage of metal nanowire.
6. The method for preparing of composite carbon nanotube (CNT) as claimed in claim 1, wherein the thermal processing of carbon nanotube (CNT) yarn comprises heating with a laser in a high vacuum atmosphere in presence of inert gas.
7. The method for preparing of composite carbon nanotube (CNT) as claimed in claim 1, wherein heating occurred at high vacuum of 10-6 – 10-7 Torr and at a temperature of 800 - 1000°C in presence of inert gas such as Ar, H2, O2 and N2.
8. The method for preparing of composite carbon nanotube (CNT) as claimed in claim 1, wherein the laser can be selected from CO2 and diode laser.
9. The method for preparing of composite carbon nanotube (CNT) as claimed in claim 1, wherein the speed of laser scan is 1 to 10 mm/sec.
10. The method for preparing of composite carbon nanotube (CNT) as claimed in
claim 1, wherein the angle of true-twisting of CNT yarn is 15 - 30°.