Masterbatches of carbon nanotubes provide benefits of strength and electrical conductivity at low levels

The world�s largest producer of carbon nanotubes, has added five resin families of commercial-quantity thermoplastic masterbatches containing Fibril multi-walled carbon nanotubes. This high aspect ratio, curvilinear form of graphitic carbon confers electrical conductivity at lower loadings than other conductive additives when compounded with otherwise-insulating materials such as thermoplastics. All masterbatches are supplied by the pioneer of carbon nanotubes, Hyperion Catalysis International- in pellet form. Processors can vary the letdown ratio on the masterbatches to optimize the conductivity level of a moulded plastic part to meet its end-use application requirements. The five new masterbatches are as follows:
-Polyetheretherketone (PEEK)
-Polyetherimide (PEI)
-Polyphenylene sulphide (PPS)
-Polystyrene (PS)
-Nylon (Polyamide (PA))12

Carbon nanotubes are 10-12 nm in diameter � more than 5,000 times thinner than a human hair � and 10-15 microns (m) long. Due to their unusually high? (aspect ratio (1:1,000+), these sub-microscopic tubes provide a highly effective, electrically conductive network when compounded with non-conductive materials, even at low loadings. In the automotive industry, thermoplastic compounds using Fibril nanotubes are capable of producing Class A body panels and trim parts. Since the resulting parts also have conductive properties, they can be electrostatically painted, eliminating primer steps and making it easier to wrap paint around corners and into deep design details. Low loading levels mean nanotubes do not compromise important mechanical properties (eg low-temperature ductility), so parts can be used in large exterior panels as well as trim applications. The nanotubes are also a key additive in nylon fuel lines where they prevent dangerous static discharges while preserving the low-temperature ductility of the nylon. In the electronics field, the smooth, highly homogeneous part surface means minimal sloughing (rub-off) of surface particles, which can be a damaging contaminant in today�s ultra-clean, electronic production environment.
The nanotubes are non-reactive and chemically clean, with no sizing agent or sulphur that can damage delicate microelectronics. Hence, Fibril-filled compounds are used to mould silicon-wafer handling tools (tweezers, wands, and rails for front opening unified pods (FOUPs)), as well as material transport trays and components for computer hard drives. As these nanotubes are so small and strong, they offer higher regrind stability than other conductive additives, making it easy to melt reprocess runners, sprues, and parts during production, as well as recycle moulded components at end-of-life. Current markets include automotive and electronics, and other uses in batteries, fuel cells, flat-panel displays, and catalyst supports are under development.

The number of players in the carbon nanotube field has extensively grown after the expiry of the patent held by Hyperion. In 2006, Bayer MaterialScience unveiled a process which used Catalytic Chemical Vapour Deposition (CCVD) for making electrically conductive MWCNTs (multi-walled carbon nanotubes) on a commercial scale with consistent purity and considerably lower cost. Baytubes have potential in markets like automotive paintings, electronics packaging and shielding electronic accessories. They reportedly comprise up to 15 graphene layers against other MWCNTs which have 6-7 layers. Recently, Bayer MaterialScience and Clariant Masterbatches signed a cooperation agreement in which the former will supply Clariant with industrial quantities of high-quality Baytubes� for the manufacture and development of compounds and master batches. Future applications for the resultant compounds include electrically conductive machine components and packaging for delicate electronic components such as computer chips. CESA� conductive CNT impart conductive properties to thermoplastics.
American nanotechnology company, Zyvex Corporation makes carbon nanotubes compatible for plastics and other materials using its Kentera technology. France�s Arkema has been supplying its MWCNTs, Graphistrength to Zyvex. Zyvex�s patented Kentera technology (a non-covalent modification of carbon nanomaterials) exfoliates, disperses, and adheres to the host material when it is combined with nanomaterials. This creates a NanoSolve additive or concentrate � successfully transferring the physical properties (including electrical and mechanical) to the host polymer. Some time ago, Zyvex announced the world�s first yacht mast using carbon nanotubes. Use of NanoSolve materials made it some 30% stiffer than a conventional high performance composite mast of the same weight. Like other high-performance masts, this one is made of layers of carbon fibre fabric bonded together with epoxy � a nanotube-containing epoxy. NanoSolve materials are also being used in a variety of sporting supplies.

Unlike carbon nanotubes, carbon nanofibres have a diameter between 70 and 200nm particularly due to a thicker wall of more than of 20nm. Distinct from the CNTs� graphene layers wrapped into cylinders, the layers in carbon nanofibres are arranged as stacked cones, cups or plates. Both types are most commonly made using catalytic chemical vapour deposition. Nanofibres exhibit properties between those of nanotubes and carbon fibers. Addition rates in compounds range from 3-8% by weight. Amongst the prominent suppliers in carbon nanofibers include the American company Pyrograf Products and the Austrian company Electrovac. The Austrian company sells nanofibres only in masterbatch and compound form and mainly gearing towards auto fuel systems and the electronic wafers business. Carbon nanofibers-containing compounds are based on a wide range of amorphous and semicrystalline polymers. The compounds are characterized by electrical conductivity suitable for dissipative and electromagnetic shielding, and have better mechanical properties than the unmodified polymer. The carbon nano fibers provide compounds with higher temperature stability, better flow properties and outstanding surface quality. Pyrograf had worked with companies producing conductive thermoplastic composite components to replace carbon steel in electrostatic precipitators for the coal powered plants. Also, work had been done on ESD painting of composite body panels where CNFs can improve electrical conductivity and strength. A lot of study had also dedicated to using CNF-enhanced PEEK composites for under hood automotive and aerospace applications.

碳纳米管和纳米纤维进攻r immense potential is not news. The increasing number of entrants and studies undertaken for the development and applications of the CNT technology is set to give it a massive boost particularly in fields of automotive components, electronics, sports & leisure, packaging and the like. The unique electrical, mechanical and thermal properties of CNTs make them suitable for a tremendous variety of applications.