I. Introduction to Carbon Nanotubes
1.1. What is Carbon Nanotube
Carbon materials exist in multiple forms such as diamond, graphite, fullerenes, and carbon nanotubes (CNTs). These many different carbon materials arise because carbon atoms can form several hybridized orbitals and achieve relatively stable structures with different valence bonding. Geometrically, a CNT can be constructed by rolling a piece of graphene to create a seamless nanometerscale cylinder.
Depending on the process for CNT fabrication, there are two types of CNTs: single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs). SWCNTs consist of a single graphene layer (Fig. 1.1A) rolled up into a seamless cylinder whereas MWCNTs consist of two or more concentric cylindrical shells of graphene sheets (Fig. 1.1B) coaxially arranged around a central hollow core with van der Waals forces between adjacent layers.
1.2. Overview of Global Carbon Nanotube Market
According to the report: Carbon Nanotube (CNT) Market – Global Forecast to 2023. This report forecast the consumption of CNT in 2023 with the table below:
II. Some Applications of Carbon Nanotube
2.1. Polymer-Nanotube Composites
The spectacular properties of CNTs such as their high strength and stiffness make them ideal candidates for structural applications. At present, polymer nanocomposite is one of the biggest application areas for CNTs. The extraordinary properties of CNTs coupled with easily
tailorable characteristics of polymers give rise to truly versatile CNT-polymer nanocomposites. By definition, a composite is a multiphase material formed from a combination of materials which differ in composition or form, retain their own chemical and physical properties, and
maintain an interface between components which act in concert to provide improved specific or synergistic characteristics not obtainable by any of the original components acting alone. The reinforcements contribute useful properties (mechanical, electrical, thermal, optical, etc.) to enhance the matrix properties. In the past decades, we have reached the technological design limits of optimizing composites with traditional micro-meter scale fillers/reinforcements. Table 1 shows a comparison between various fibre reinforcements and carbon nanotubes in terms of various parameters.
2.2. Electrical and Electronics
2.2.1. Electrostatic Discharge (ESD)
Electrostatic Discharge CNT/PS compound tray of Dai A Industry Joint Stock Company produces to the application of mobile phone/electronics. The thermoforming process widely used to produce ESD tray and the surface resistivity of the ESD tray reaches 104 Ohm/cm2.
2.2.2. Electrical Conductivity of Carbon Nanotube Based Nanocomposites
The Theory
The microstructure of CNT based nanocomposites can be conceived to be a two-phase composite, with carbon fillers as the inclusions and polymer binder as the matrix. All inclusions are assumed to have spheroidal shapes. CNT inclusions correspond to prolate spheroids with high aspect ratios. Compared with long cylindrical CNTs, a prolate spheroidal CNT will possess almost the same shape when its aspect ratio is sufficiently large. The dispersion state of CNT inclusions is considered to be homogeneous and their orientations are totally random. This microstructure is schematically shown in Fig. 4.1.
The Effective Electrical Conductivity of CNT Nanocomposites
To verify our continuum composite model, we take two steps to study the experimental data of the electrical conductivity of CNT nanocomposites. In the first step, the composite is taken to be homogeneous. We use the effective-medium approach with interfacial resistance and tunneling-assisted interfacial conductivity to study two sets of experimental data by Ngabonziza et al. (2011) and McLachlan et al. (2005) showing notable percolation phenomena. The first set of data involved multi-walled CNTs in the polyimide matrix, while the second set was with single-walled CNTs and also the polyimide matrix. The intrinsic electrical conductivity of CNTs and the matrix are both given in the original papers and are listed in Table 4.1.
2.2.3. CNT in LCD Display
LCD is the mainstream product in the present display market. The basic principle of LCD is that liquid crystal (LC) molecules work as a light valve to control the light. The LC molecule is usually a rod-like (calamitic) or disk-like (discotic) shape and can rotate under an electric field. A typical LCD structure is shown in Fig. 4.5. It can be seen that the whole structure is composed of an LC molecule cell, transparent electrode, backlight module, TFT, color filter, polarizer, connection wire, etc. Correspondingly, we can find the applications of CNTs in the different parts of the LCD. The CNT itself can be viewed as a large rod-like molecule and shows an LC-like behavior. LC molecules have been mixed or integrated with CNTs, and it is found that the LC can align CNTs, or CNTs can also be used to align LC molecules. The LC with CNTs also shows a better performance over the original ones.
III. Top Manufacture
3.1. Nano-C
Through its family of fullerenes, carbon nanotubes, and their chemical derivatives, Nano-C has managed to harness the power, flexibility and cost-advantages of carbon – the strongest, environmentally safe and most abundant element on earth. These materials enable devices that are more durable and lighter weight, use materials and energy with greater efficiency, and are inherently more versatile all at a lower total cost to the consumer. As a result, Nano-C materials are now being used by electronics and energy leaders throughout the world to deliver a new new era in sleek new products and green solutions to power our world well into the future.
3.2. Nanocyl
Nanocyl SA was founded in 2002 in Belgium and has been one of the pioneers in the manufacturing of industrial multiwall carbon nanotubes (MWCNTs). They are a worldwide industry leader in the development, manufacturing and sales of multiwall carbon nanotubes (MWCNT) and MWCNT based formulated products. The mission is to support our customers’ growth with top of the class industrial MWCNT, MWCNT formulated products and sustainable long-term performance solutions.
3.3. Kumho Petrochemical
Kumho Petrochemical, founded in 1970 and possessing the largest synthetic rubber manufacturing capacity in the world, is doing businesses in various fields, such as synthetic resins, specialty chemicals, nanocarbon, energy, and building materials. Kumho Petrochemical, which has grown as an active player in Korea’s industrial development for the past 50 years, will stand at the forefront of material innovation and will become a global petrochemical company that develops and provides higher values.