ADDITIVES | ELECTRICALLY CONDUCTIVE
Right: Fuel pumps are an example of automotive parts produced using
electrically dissipative plastics
claims.Sordi says that these features are particularly applicable for products such as casings in electric vehicles (EVs), where the goal is not only to provide adequate EMI shielding around the EV battery and other under-the-hood components, but also ensure greater impact resistance and reduce the overall weight of the casings. Recent results have confirmed the synergistic
effect of the CarbonX material for EMI shielding and ESD applications. “We found that when CarbonX is used as a polymer filler on its own, 60dB EMI shielding could be achieved,” says Sordi. “Interestingly, when CarbonX was combined with other fillers, a synergistic effect resulting in greater EMI shielding effectiveness was observed.” The synergistic effect of CarbonX can also be observed in applications requiring electrostatic dissipation, such as crates and pallets used to transport electronics or flammable substances. “Glass fibres can be partially replaced by
CarbonX,” says Sordi. “We tested the mechanical properties and the conductivity of a polyamide 6 reinforced with only glass fibres against PA6 reinforced with both glass fibres and CarbonX [grade X7].” The results showed a significant synergistic effect in terms of strength (Young’s Modulus) and volume resistivity, while yield stress is only slightly reduced (Figure 1).
CNT application Carbon nanotubes (CNTs) continue to demonstrate their effectiveness as conductive additives for plastics, according to Nanocyl, a leading producer of multiwall CNT variants (MWCNT) and formulated products based on them. “CNT’s elongated structure is what makes it so special compared to other carbon-based additives,” the company claims. “Nanocyl’s thin, entangled and flexible nanotubes tend to form network-like structures when dispersed in a matrix. A small percentage of carbon nanotubes already endow electrically
Figure 1: A comparison of strength (Young’s Modulus), yield stress and volume resistivity of two PA6 compounds, one containing glass fibres and the other a combination of glass and CarbonX Grade X7, showing a synergistic effect
Source: CarbonX 18 COMPOUNDING WORLD | February 2021
www.compoundingworld.com
dissipative properties to the matrix while maintain- ing or even improving its other characteristics.” Nanocyl’s formulated products include its Plasticyl range of polymer masterbatches, which are loaded with its NC 7000 MWCNT. The company says these materials are already used in automobile fuel pumps and fuel lines. “Chosen Plasticyl grades ally the stringent requirements of high heat resistance and chemical resistance to various fuels with the requested ESD properties,” it says. Other current applications include parts that need to be painted, where the nanotubes provide conductivity for electrostatic painting and can obviate the need for conductive primers. The Covid-pandemic had a huge impact on
aircraft production. Consequently, demand for raw materials such as aerospace-grade carbon fibre has dropped and is expected to remain at a low level for some years. Carbon fibre demand is also being impacted by calls to cut CO2
emissions. “These two
elements are at the basis of the strongly growing interest for recycled carbon fibre today,” says Procotex, a supplier of such fibres. The company says that supply of virgin carbon
fibre — especially aerospace-grade fibre — is currently low while most virgin industrial-grade carbon fibre is likely to be consumed by emerging
IMAGE: NANOCYL
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