Page 1

Carbon nanomaterials for a space elevator scientist000001 a) (Dated: 28 March 2012)

A problem whether a space elevator can be made using macro structures made of carbon nanotubes (CNTs) was discussed by ideal models of CNT yarn and sheet and experimental data reported by other groups. The result of discussions says that it is important for the tensile strength of CNT yarn and sheet to enhance the adhesion rate, which is the density of CNTs in the cross section of CNT yarn and sheet and the overlap length of each CNT in the long direction. It is concluded that even current CNT yarn and sheet can become materials for the space elevator by approaching the ideal adhesion rate. Keywords: space elevator, carbon nanotube, yarn, sheet By increasing number of people, the people’s work area will have to move from the earth to the space in the near future. Now they go to the space using the space ship. But it cannot carry a lot of people in one flight. Furthermore there are some problems of the cost and air pollution by burning the fuel of space ship. Therefore it is necessary to propose an easier method for going to the space.

I.

INTRODUCTION

There is a space elevator as one of new methods to efficiently go to the space.1 At this stage it is considered that the space elevator is most suitable to go to the space. The material with both a lightweight and high strength is necessary to make it. There is a carbon nanotube (CNT) made of carbon atoms as one of the suitable materials. They say that CNT has low mass density (1.31.4 g/cm3 )2 , high tensile strength3–6 , and electrical7,8 and thermal (3500 W/mK)9 conductivity. The tensile strength of a single CNT is shown in table I. Table I indicates that the strength of CNT is strong enough to make the space elevator. The tensile strength of more than 100 GPa is necessary to make the space elevator. 1 Therefore the CNT is strongly expected to make the space elevator. The material with such tensile strength will affect to not only the aerospace industry, but also building industry,

TABLE I. Tensile strength of a single-walled CNT (SWCNT) and a multi-walled CNT (MWCNT) obtained by theory and experiment.3 –6 CNT SWCNT SWCNT MWCNT MWCNT

a) Electronic

Tensile strength [GPa] 300 150–180 138 150

Method Reference Theory 3 Theory 4 Theory 5 Experiment 6

mail: science000001@aol.com

electric power industry, clothing industry and medical industry. If CNTs with the infinity length can be made, the space elevator has already been completed. However the space elevator isn’t made yet, because there are no suitable materials for it in this world. Although in order to make the space elevator, CNT has to be an infinity length without the reduction of strength, it is difficult to make such CNTs because of the problem of lifetime of CNT catalysts by the growth of chemical vapor deposition (CVD). 10 As a long-CNT structure, a CNT yarn and sheet have been reported.11–39 Figure 1 shows the side view of schematic illustration for the macrostructure using CNTs. Figure 1(a) and (b) are the model for the ideal CNT and the current CNT yarns and sheets, respectively. Current CNT yarns and sheets are composed of bundled CNTs as shown in Fig. 1(b). There are 2 methods to make such long-CNT structures. One is the method that obtains from the vertically aligned CNTs. Most CNT yarns and sheets are made by this method. Another is the method that obtained directly from CNTs growing in a vertical CVD reactor. This method can make mainly CNT yarns. It is reported that each method is based on the bundled CNTs due to Van der Waals force on the CNT surfaces. The tensile strength of most CNT yarns and sheets, which have already been reported, is several GPa as shown in Fig. 2. Most strengths are lower than those of existing carbon fiber (7 GPa of T1000 made by TORAY) and organic fiber (5.7 GPa of ZYLON made by TOYOBO). Recently T. Filleter has reported the tensile strength of 17.1 GPa by the surface modification of CNTs.33,34 The tensile strength of CNT yarn strongly affects to the surfaces. And Fig. 2 also shows that the number of research groups increases every year. It is (a)

CNT (b)

FIG. 1. A side view of schematic illustration for the macrostructure using CNTs. Figure 1(a) and (b) are the model for the ideal CNT and the current CNT yarns and sheets, respectively.


2

Tensile strength (GPa)

20

10

n=3

0

2002

2004

2006 2008 Year

2010

n=2

n=1

n=0

n=1

n=2

n=3

2012

FIG. 2. Tensile strength of CNT yarns versus year which was reported them.11 –39

found that CNT yarns and sheets are attended by many people. Why is the tensile strength of CNT yarns and sheets much lower than that of a single CNT shown in table I? In this report, I would like to discuss this and if the space elevator can be made using them.

II.

MODELS

At first, the tensile strength is discussed using simple models for CNT yarn and sheet. Figure 3 shows a side view of a structure formed by bundled CNTs. Thick and thin lines show pulled CNTs and fixed CNTs respectively. When CNTs are pulled, the friction force is applied at the overlapped surfaces between fixed CNTs and pulled CNTs, which are surrounded by dotted lines. The force is applied here. This side view can be applied for both CNT yarns and sheets. In the actual CNT yarns and sheets, this pattern is repeatedly connected to the long direction, while the pulled and fixed CNTs are replaced. Figure 4 shows the cross sectional view of a CNT yarn

Fixed

FIG. 4. A cross sectional view of a CNT yarn of a long direction. Thick and thin lines show pulled CNTs and fixed CNTs respectively.

of a long direction. The side view of this model is shown in Fig. 3. Each circle in Fig. 4 is the cross section of CNTs. Thick and thin lines also show pulled CNTs and fixed CNTs, respectively. The contact points that the force is applied are shown by dotted circles. n is the number of CNT layers to be the diameter of this CNT yarn. The diameter of this model increases with the increase in n. This arrangement of CNT has the maximum density of CNTs. Here, it thinks of a tensile strength of this ideal model using the friction force at CNT surfaces. The tensile strength Ftensile of the model can be expressed by the total number of contact points with the friction force, as shown by Ftensile =

X

FN

(1)

N

where FN and N are the friction force at each contact point and the total contact point, respectively. The unit is N. This can be expressed as follows by normalizing using the cross sectional area of the model.

Fixed CNT Pulled CNT Fixed CNT Pulled CNT Fixed CNT Pulled CNT Fixed CNT Pulled CNT Fixed CNT

FIG. 3. A side view of a structure formed by bundled CNTs. Thick and thin lines show pulled CNTs and fixed CNTs respectively. When CNTs are pulled, the friction force is applied at the overlapped surfaces between fixed CNTs and pulled CNTs, which are surrounded by dotted lines.

Ftensile = Fff · N · S −1

(2)

where Fff is the friction force at the CNT surface. It was assumed that the friction force is constant at all contact points. N and S are the total number of contact points and the cross sectional area surrounded by hexagon in Fig. 4, respectively. The unit is Pa. N and S of this model are given by N = 6(n2 − 5n + 5)

(3)

√ 3 3 S= (Dyarn )2 8

(4)


3

n=0

n=1

n=2

n=3

n=4

n=5

FIG. 5. A cross sectional view of a CNT sheet with a single layer of a long direction. Thick and thin lines show pulled CNTs and fixed CNTs respectively. This is called CNT sheet1.

where n, Dyarn and DCNT are the number of layers (n = 0.5 ¡ Dyarn /DCNT , n ≼ 1), the diameter of CNT yarn and the diameter of CNT, respectively. Next, it thinks a model of a CNT sheet as shown in Fig. 5. This model is the cross sectional view of CNT sheet with a single layer. This is called CNT sheet1. n is the number of CNTs to be the width of CNT sheet. The side view of this model is shown in Fig. 3. For this model, N and S are given by

N =n=

Wsheet −1 DCNT

S = Wsheet ¡ DCNT

where nx and ny are the number of CNTs in the width direction (nx = Wsheet /DCNT ) and the number of CNT layers, respectively. The model in Fig. 6 is called CNT sheet2. These three Ftensile for N and S indicate that the friction force on the surfaces and the number of contact point are important for CNT yarn and sheet. This S is also the area surrounded by solid line. Ftensile and N mean the adhesive force and the adhesion rate, respectively. The adhesion rate also includes overlap lengths of each CNT of the long direction as shown in Fig. 3. As the unit of Ftensile in expression (2) is Pa, Ftensile of each model converge with the increase in Dyarn and Wsheet. When Dyarn and Wsheet are infinity, Ftensile of these three models can be summarized as follows.

Ftensile = Fff ¡ k ¡

ny=2

(DCNT )

2

(9)

(5)

where k for CNT yarn, CNT sheet1 and CNT sheet2 are

(6)

4 k= √ 3

(10)

k=1

(11)

where Wsheet is the width of CNT sheet. S is an area surrounded by solid line. In the case of the CNT sheet with multi layers as shown in Fig. 6, N and S are given by

ny=1

1

N = 2(nx − 1)(n y − 1)

(7)

√   3 S = Wsheet ¡ DCNT 1 + (ny − 1) 2

(8)

nx=1 nx=2 nx=3 nx=4 nx=5 nx=6 nx=2 nx=3 nx=4 nx=5 nx=6 nx=7

ny=3 ny=4 ny=5

k=

(12)

, respectively. Ftensile cannot continue to be high by increasing Dyarn and Wsheet . This means that the adhesive force and adhesion rate are very important for the strength of CNT yarn and sheet. When the diameter of CNTs becomes small, Ftensile becomes high for all models because the density of CNTs becomes high and the number of contact points increases. As other model of CNT yarn, Juan J. Vilatela, et al. have reported that larger diameter CNTs with fewer walls have a greater degree of contact, as determined by continuum elasticity theory, molecular mechanics, and image analysis of transmission electron micrographs.40 Also they say that the adhesive force and adhesion rate are important for CNT yarn.

III.

FIG. 6. A cross sectional view of a CNT sheet with multi layers of a long direction. Thick and thin lines show pulled CNTs and fixed CNTs, respectively. This is called CNT sheet2.

2(ny − 1) √ 3 1+ (ny + 1) 2

VAN DER WAALS FORCE

Here, it thinks of the friction force Fff at each contact point. At first, it thinks of Van der Waals force because it is generally reported as the force forming CNT yarn and sheet. Van der Waals force when the surfaces of two cylinders are contacted is given by


4 TABLE II. Tensile strength of CNT yarn and sheets calculated using values of Fff = FVdW , DCNT = 10 nm, Dyarn , Wsheet → ∞. Model type CNT yarn CNT sheet1 CNT sheet2

Tensile strength [GPa] 0.00553 0.00239 0.00409

FVdW

A = √ 3 12 2 · d 2

r

R1 R2 R1 + R2

(13)

Friction force on CNT surface (nN)

where R1 and R2 are the diameter of each cylinder, d is the spacing of two CNTs (0.34 nm), A is the Hamaker constant (5.10×10 −19)41 .42 Using R1 = R2 = 10 nm, Van der Waals force (FVdW ) is 0.339 nN. The tensile strength Ftensile is shown in table II using this FVdW , DCNT = 10 nm, Dyarn and Wsheet = infinity. The density of CNTs in the cross section is shown in Fig. 4, 5 and 6. It is considered that the density is much larger than that of actual CNT yarn and sheet. When Fff is FVdW , the tensile strength for all models is much lower than those shown in Fig. 2. From this result, it is considered that the surfaces of CNT yarn made experimentally have a force except Van der Waals force. In order to investigate the origin of the force, Fff was calculated using the expressions (2), (3), (4) and the experimental data in Fig. 2. For this calculation, the reports that the diameter of CNT yarn and CNTs and the tensile strength of CNT yarn are displayed in Fig. 2 were used. Those were substituted to the expressions. The density of CNTs in the cross section of CNT yarn shown in Fig. 4 is used to this calculation. The density of CNT in CNT yarn was assumed for this calculation as the maximum density. Figure 7 shows the friction force Fff on CNT surfaces dependence on the tensile strength 80

60

40

20

0 0

1 2 3 Tensile strength of CNT yarn (GPa)

4

FIG. 7. Friction force on CNT surfaces calculated from tensile strength of CNT yarn obtained from references14 ,16–18,21–23,25 using the model of Fig. 4 and expressions (2), (3) and (4).

of CNT yarn obtained from references14 ,16–18,21–23,25. It is found that the friction force on the CNT surface increases with the increase in the tensile strength of CNT yarn. The values of the force are hundreds of times higher than Van der Waals force. These were calculated using the model with the ideal adhesion rate of CNTs in the cross section of CNT yarn. Hence it is considered that the actual friction force will become higher. This figure reveals that the origin of the tensile strength of CNT yarn is not only Van der Waals force, but also other force. It is considered that the other force occupies most of the original force. By the way, in Fig. 7, the friction force seems to be saturated when the tensile strength approaches 3 GPa. This may indicate the limitation of friction force of CNTs grown by current CVD and twine methods, although it has no information if this is true since there are few data. The detailed information will be obtained by the increase in data.

IV.

CNT SURFACE

It was found that the origin of force for forming CNT yarn is mainly except Van der Waals force. Here, it would like to discuss about the force and what there is on CNT surfaces. In generally, CNTs for CNT yarns are grown by CVD. When CNTs are grown by CVD, an amorphous-carbon (a-C) layer is formed on the CNT surfaces.43 The a-C layer has the roughness in nanoscale and defects on the surface. The amount of a-C will depend on the growth condition during CVD. If there is no a-C layer on the CNT surface, the friction force will be only Van der Waals force because of the graphene surface.44,45 This indicates that the friction force by the surface with a-C layer is the origin of force for forming current CNT yarns and sheets. And also this indicates that it is difficult to make the CNT yarn and sheet from only pure CNTs. By the above discussions, it was found that the adhesive force of CNT yarn and sheet is mainly due to the friction force of the a-C layer on the CNT surfaces. They say that Van der Waals force doesn’t depend on the overlap length of bundled two CNTs. If the surface of CNT has the roughness in nanoscale, it is considered that the friction force of the surfaces linearly increases with the increase in the overlap length. Next, it thinks the friction force on the CNT surface. A report related to the static friction force of CNT surfaces was found.46 They have measured the static friction force on the CNT surfaces with the a-C layer using a nanomanipulator installed in transmission electron microscope. Their report says that a-C layer on the CNT surface makes the friction force for forming CNT yarn. Here, it discusses the friction force on the CNT surface using data from their report. In generally, the static friction force Fmax between 2 objects is given by


5

Fmax = τi · Ar

(14)

where τi is the shearing force, Ar is the real contact area. And Ar for CNT can be expressed as follows. Ar = Loverlap · w

ADHESION RATE

Ratio of Ftensile-EX and Ftensile-CAL (%)

In order to investigate the adhesion rate of current CNT yarns in Fig. 2, the ratio of Ftensile−EX reported by references14 ,16–18,21–23,25 and Ftensile−CAL calculated using the model with the ideal adhesion rate in Fig. 4 was calculated. (Ftensile−EX/Ftensile−CAL ) × 100 was calculated. For calculating Ftensile−CAL , the values of τi = 76.7 MPa, w = 0.854 nm, diameters of CNT and CNT yarn from references14 ,16–18,21,25 were used. A half of the length of CNT from references14 ,16–18,21,25 was used as the overlap length. Figure 8 shows the calculation result. Each ratio of Ftensile−EX and Ftensile−CAL is less than several % for all tensile strength which were reported. This means that the current CNT yarns can be compressed to the cross sectional direction further by more than tens of times. It is considered that the limitation of the tensile strength of current CNT yarns is 3

2

1

0 0

1 2 3 Tensile strength of CNT yarn (GPa)

Model type CNT yarn CNT sheet1 CNT sheet2

Tensile strength [GPa] 149.85 65.54 134.15

(15)

where Loverlap is the overlap length of bundled two CNTs, w is the overlap width on the cross section of the two deformed CNTs. In their report, the friction force is almost proportional to the overlap length. And Loverlap and w are 148 nm and 0.854 nm, respectively.46 Fmax for Loverlap = 148 nm is 9.7 nN.46 Using these values, τi of the CNT surfaces with a-C layer grown by CVD can be obtained 76.7 MPa. The adhesion rate of CNT yarn will be discussed at next section using this τi . V.

TABLE III. Tensile strength calculated using τi , Loverlap = 100 µm, DCNT = 10 nm, Dyarn = 10 µm, Wsheet = 5 cm, ny = 10 and models of Figs. 4, 5 and 6.

4

FIG. 8. Ratio of Ftensile−EX reported by references14 ,16–18,21,25 and Ftensile−CAL calculated using the model with the ideal adhesion rate in Fig. 4.

due to low adhesion rate of each CNT yarn. It can be considered that the variation of tensile strength shown in Fig. 2 is due to the variation of adhesion rate of each CNT yarn. For this, the values of tensile strength for the models in Figs. 4, 5 and 6 were calculated to investigate the tensile strength of CNT yarn with the ideal adhesion rate. The values of τi = 76.7 MPa, Loverlap = 100 mm, DCNT = 10 nm, Dyarn = 10 mm, Wsheet = 5 cm, ny = 10 were used to this calculation as parameters. Table III shows the calculation results. Those tensile strengths are much higher than those in Fig. 2. Especially, about 150 GPa in the tensile strength of CNT yarn is obtained. This indicates that the friction force on the surface of a-C layer has enough strength when the adhesion rate approaches to the ideal adhesion rate. However in order to know if such tensile strength can be actually obtained, it is necessary to measure the adhesive force between CNT surfaces and a-C layer. CNTs grown by CVD have defects on the surfaces on graphene.47,48 Although there is Van der Waals force on the surfaces of high-crystallinity CNTs, the CNT surfaces grown by CVD will have the force due to the defects except it. 48 I think that the a-C layer is formed when the defects on the surfaces play the role of an anchor. The defects as the anchor may become the nucleus to grow a-C layer. The anchor which is the interface between the CNT surface and the a-C layer is very important for the tensile strength of CNT yarn and sheet. And this is the reason that the friction force on CNT surfaces with a-C layer is much larger than Van der Waals force. For the macro structures using bundled CNTs, I think that the limitation of tensile strength will be this adhesive force rather than the strength of CNT itself, when the adhesion rate of CNT yarn approaches to the ideal adhesion rate. Although it was found that the CNTs with a-C layer on the surfaces are matched for CNT yarn and sheet better than the pure CNTs, also I think that it is important to investigate the difference of the CNT with a-C layer on the surface and the nanorod formed by a-C in the future. The structure of a-C layer on the CNT surface may differ from the nanorod formed by a-C. If the tensile strength of carbon nanorod which is made of a-C is larger than the friction force on the surface of the nanorod, the yarn made by such nanorods may be almost the same to the yarn made by CNTs. It is considered that the friction force affects to the initial stage of making CNT yarn. When the friction force is too low or is too high, no CNT yarn can be made.


6 I think that when the friction force is suitable to make CNT yarn, the adhesion rate will be high because it is easy to perform the self organization. This indicates that the surfaces of current CNT yarn may have no suitable a-C layer. Therefore, the adhesion rate is low. The surface modification of CNT is also necessary to enhance the adhesion rate. High adhesion rate will lead to not only higher tensile strength, but also higher electrical and thermal conductivity. I propose that there are following 5 methods to obtain high adhesion rate. 1. Optimizing a-C layer by adjustment of growth condition during CVD. 2. Making defects on CNT surfaces without a-C layer and using them as an adhesive. 3. Using suitable adhesive to as-grown CNT.

making the long graphene sheet is much easier than doing the long CNTs. Although most researchers have been researching dissolving bundled CNTs and removing a-C and impurities on the CNT surfaces so far, researching the strong bundled CNTs and adhesive for the CNT surfaces is very important for the macro structures using CNTs. Such researches will lead to new properties and applications using CNTs in the future. It is considered that when the CNT surface is changed, the suitable twine method is also changed. As the method 5, the CNTs prepared by the methods of 1 to 4 are spun by optimized twine method. It is considered that CNT yarn and sheet with the high tensile strength can be made by above 5 methods. A process summarized these 5 methods is shown at the next section using a schematic illustration.

4. Filling dead space by adhesive. VI.

PROCESS

5. Optimizing twine method. It is considered that a-C layer on the CNT surfaces can be adjusted by the growth condition of CVD. In the method 1, the a-C layer is optimized by it. For the method 2, the defects on the surface of graphene are anchor for a-C layer. The connection between CNTs by the defects can be considered. As this method reduces the strength of CNT itself, the balance between the number of defects and the strength of CNT will be important. Here, the strength of CNTs with the defects has to be clarified. As the adhesive in the method 3, that of current CNT yarns and sheets is a-C layer. The friction force on the surface of a-C layer is the origin of the force for forming current CNT yarns and sheets, as mentioned above. However, no one knows yet if the a-C layer is most suitable as an adhesive of CNT yarn and sheet. Therefore it is important for the macro structures using CNTs to look for the suitable adhesive for the CNT surface. Al2 O3 , W, SiO2 , Ti, WS2 , ZnO and etc which are used as materials to coat the CNT surface can be considered as the candidates of the adhesive.49–53 It is necessary for them to measure the friction force on each surface. When CNTs most suitable for CNT yarn and sheet are made, we may feel high viscosity from such CNTs. I think that this will be a new property for CNT. I think that fullerene, graphene, SWCNT and doublewalled CNT (DWCNT) can also become the candidates, because those materials are made of carbon atoms and the structures are much smaller than that of multi-walled CNTs which are used as materials for CNT yarn and sheet. Those materials will be able to fill the dead space in the macro structures using CNTs. In the method 4, the adhesion rate is enhanced by filling the dead space. As an other method to fill the dead space of CNT yarn, a structure rolled a long graphene sheet may also become one of the candidates of high strength yarn. I think that

It thinks the method to make CNT yarns with the high tensile strength using a schematic illustration. Figure 9 shows the schematic illustration of a process to make CNT yarn and sheet from an assemblage of CNTs. This process has 4 sections. The 1st section is an area with the assemblage of CNTs (like a CNT cloud). Or that is an area where CNTs are grown by CVD. This section is corresponding to the 1st method in 5 methods mentioned at the section of ADHESION RATE. In the 2nd section, the adhesive is adhered to the CNT surfaces by dipping into the adhesive solution or passing into the humidified space with the adhesive solution. Here I think mainly fullerene, graphene, SWCNT and DWCNT as the adhesive. Some surfactants may be able to be used here. I think that the adhesive can be adhered easily by dissolving the bundles of CNTs using the sur-

CNTs

1 st section

2nd section

3rd section

4th section

FIG. 9. A schematic illustration of a process to make CNT yarn and sheet from an assemblage of CNTs. The 1st section is an area with the assemblage of CNTs (like a CNT cloud). Or that is an area where CNTs are grown by CVD. In the 2nd section, the adhesive is adhered to the CNT surfaces by dipping into the adhesive solution or passing into the humidified space with the adhesive solution. In the 3rd section, the adhesive on the CNT surfaces is solidified by irradiating a strong light and laser or thermally annealing in the inactive gas which is He, Ar, N2 and etc. In the 4th section, CNT yarn and sheet are winded on a spool.


7 factants. Or CNTs without dissolving bundles may be able to be adhered easily. It is necessary to investigate this. If the 1st section has a reactor for CVD, CNTs will be able to be coated using the gases of coating materials as mentioned above. In the 3rd section, the adhesive on the CNT surfaces is solidified by irradiating a strong light and laser or thermally annealing in the inactive gas which is He, Ar, N2 and etc., because fullerene, graphene, SWCNT and DWCNT using as the adhesive can absorb the light and change into heat. Especially SWCNTs become high temperature of more than 1800K by absorbing the light.54,55 I think that the heat can be controlled by the strength of light and can change the structure in SWCNT and the structure behaves as an adhesive, which adheres between CNTs in CNT yarn and fills the dead space. On the other hand, the structure of yarn doesn’t change, because MWCNTs constructing CNT yarns hardly absorb the light. For the 2nd section to 3rd section, these sections are corresponding to from the 2nd method to 4th method in 5 methods mentioned at the section of ADHESION RATE. In the 4th section, CNT yarn and sheet are winded on a spool. This process will be able to make continuously CNTs the yarn and sheet. There are some elements to research at each section. I think that CNT yarns and sheet with the high tensile strength can be produced by optimizing each section. This section is corresponding to the 5th method in 5 methods mentioned at the section of ADHESION RATE.

VII.

SUMMARY

In this report, the tensile strength of CNT yarn and sheet which are macro structures using CNTs was discussed. The origin of the force for forming CNT yarns and sheets was investigated using models with the ideal adhesion rate. The origin of the force is due to the friction force from a-C layer formed on the CNT surfaces rather than Van der Waals force. τi was calculated from the static friction force on a CNT surface with a-C layer. τi and the model say that the current CNT yarns can be compressed to the cross sectional direction further by more than tens of times. They also say that CNT yarn of 150 GPa in the tensile strength can be made by enhancing the adhesion rate of current CNT yarns. 5 methods to enhance the adhesion rate were proposed. A process to make CNT yarns with the high tensile strength was proposed. I could obtain an answer for the question whether the space elevator can be made using new CNT yarns. It can be achieved. It will expand people’s work area and lead to revitalize economy and job creation. I want to make a breakthrough for the macro structures using carbon nanomaterials.

VIII.

POSTSCRIPT

I can perform and conduct this study. And I would like to perform them. I can lead this study to a goal in 5 years. For this, I need to some partners to perform the study. Will you do collaborative research with me? I can provide all of my ideas. When you want to do collaborative research, please send an e-mail to me. science000001@aol.com 1 B.

C. Edwards, The Space Elevator NIAC Phase II Final Report (2003). 2 P. G. Collins, Scientific American , 67–69 (2000). 3 B. T. Kelly, Physics of Graphite (Applied Science, London,1981) (1981). 4 e. a. G. G. Samsonidze, Phys.Rev.Lett. 88, 065501 (2002). 5 e. a. K. M. Liew, Acta Materialia 52, 2521–2527 (2004). 6 e. a. B. G. Demczyk, Mater. Sci. Eng. A334, 173–178 (2002). 7 e. a. J. W. Mintmire, Phys. Rev. Lett. 68, 631–634 (1992). 8 C. Dekker., Physics Today 52, 22 (1999). 9 e. a. E. Pop, Nano Lett. 6, 696–100 (2006). 10 e. a. T. Yamada, Nano Lett. 8, 4288–4292 (2008). 11 e. a. H. W. Zhu, Science 296, 884–886 (2002). 12 e. a. K. Jiang, Nature 419, 801 (2002). 13 e. a. Y. L. Li, Science 304, 276–278 (2004). 14 e. a. M. Zhang, Science 306, 1358–1361 (2004). 15 e. a. M. Zhang, Science 309, 1215–1219 (2005). 16 e. a. T. Mirfakhrai, Smart Mater. Struct. 16, S243 (2007). 17 e. a. X. Zhang, Small 3, 244–248 (2007). 18 e. a. X. Zhang, Adv. Mater. 19, 4198–4201 (2007). 19 e. a. K. R.Atkinson, Cond. Mater. 394, 339–343 (2007). 20 “National reconnaissance office,” (2009). 21 e. a. K. Liu, Nanotechnology 21, 045708–1–7 (2010). 22 e. a. X. H. Zhong, Adv. Mater. 22, 692–696 (2010). 23 e. a. K. Liu, Nanotechnology 21, 045708 (2010). 24 e. a. K. Liu, (2010), ACS Nano Article ASAP (submitted). 25 e. a. L. Zheng, Small 6, 132–137 (2010). 26 J. Dorr, NANOCOMP 2010 (2010). 27 e. a. C. Fang, Appl. Phys. Lett. 97, 181906–1–3 (2010). 28 e. a. M. T. Jiyoung, Mechatronics 16, 90–97 (2010). 29 e. a. Q. Zhang, Carbon 48, 2855–2861 (2010). 30 e. a. J. Ma, Sci.Tech. Adv. Mat. 11, 065005–065012 (2010). 31 e. a. M. Okada, 61st International Astronautical Congress, Prague, CZ. (2010). 32 e. a. Y. Inoue, (2011), Carbon (in Press). 33 T. Filleter, American Physical Society (APS) meeting in Dallas (2011). 34 e. a. T. Filleter, Adv. Mater. 29 (2011). 35 e. a. Tissaphern Mirfakhrai, Proc. of SPIE 6927, 692708–1 (2011). 36 e. a. T. Mirfakhrai, IEEE-ASME TRANSACTIONS ON MECHATRONICS 16, 90–97 (2011). 37 e. a. J. W. Kim, Nanotechnology 23, 035701 (2011). 38 e. a. Y. Zhanga, Carbon Available online 25 February 2012 in press (2012). 39 e. a. Y. Jia, anoscale Research Letters 7, 137 (2012). 40 e. a. J. J. Vilatela, ACS Nano 5, 1921–1927 (2011). 41 e. a. G. D. Parfitt, Trans. Faraday Soc. 64, 1955 (1968). 42 e. a. A. Artyukhin, International Journal of Nanotechnology 5, 488–496 (2008). 43 e. a. C. H. Chen, Diamond and Related Materials 14, 770–773 (2005). 44 e. a. A. N. Kolmogorov, Phys, Rev. Lett. 85, 4727–4730 (2000). 45 e. a. A. Kis, Phys, Rev. Lett. 97, 025501–1–4 (2006). 46 e. a. O. Suekane, Appl. Phys. Express 1, 064001 (2008). 47 e. a. Y. Soo, Carbon 39, 655–661 (2001). 48 J. C. Charlier, Acc. Chem. Res. 35, 1063–1069 (2002). 49 e. a. C. F. Herrmann, Appl. Phys. Lett. 87, 123110 (2005).


8 50 e.

54 e.

51 e.

55 e.

a. Q. Fu, Nano lett. 2, 329–332 (2002). a. Z. Deng, Appl. Phys. Lett. 85, 6263 (2004). 52 e. a. Raymond L. D. Whitby, Chem. Mater. 14, 2209–2217 (2002). 53 e. a. X. L. Li, Nanoscale Res. Lett. 5, 1836–1840 (2010).

a. P. M. Ajayan, Science 296, 705 (2002). a. M. Riad Manaa, J. Am. Chem. Soc. 127, 13786–13787 (2005).


Carbon nanomaterials for a space elevator  

By increasing number of people, the people's work area will have to move from the earth to the space in the near future. Now they go to the...

Advertisement
Read more
Read more
Similar to
Popular now
Just for you