TECHNOLOGY | ELECTRICALLY CONDUCTIVE
improving mechanical properties and preserving colour in a multitude of materials. Currently OCSiAl has developed Tuball-formulated technologies for thermoplastic compounds such as PE, PP, ABS, PVC plastisols, PA and PC. “Successful market products with graphene nanotubes include PVC plastisol-based antistatic ventilation ducting and fibreglass mesh for mining applications, textiles and treadmill belts,” says Bolshakov. “For example, 0.4–0.5 wt.% of graphene nanotube concentrate in PVC plastisol-based flexible ventilation ducting and fibreglass mesh for mining applications enables manufacturers to obtain a resistivity of 107
Ω/sq with maintained
Above: OCSiAl’s Tuball graphene nanotube additives are being used in ventilation ducting in mining applications
plastic could be made permanently antistatic, it would prevent dust accumulation and benefit end users. If antistatic compounds were easier to process, provided stable results and were economi- cally feasible, then we would see a rapid expansion of the conductive compounds market,” he says. “In addition, other key trends include global
green technologies - the application of environ- mentally friendly raw materials and technological processes – where there is a requirement for new products in the field of transportation and a growing demand for high-performance electronics applications,” he predicts. Nevertheless, a major technical issue remains the combination of electrical properties with desirable mechanical characteristics. “Products made by processes as different as injection moulding, extrusion, thermoforming or rotomould- ing methods require uniform, stable and perma- nent conductivity without a negative influence on their mechanical properties,” Bolshakov says. “Furthermore, the combination of electrical
characteristics and desirable mechanical properties with transparency or vivid colours is also a key target for the current market. In addition, graphene nanotubes are, probably, the only currently existing agent capable of combining and delivering these properties at a reasonable price. However, we are working on ease of integration. We are widening our product line of graphene nanotube-based master- batches with a broad technological window that can be easily introduced into various materials,” he says.
Simplified processing In order to simplify single wall (OCSiAl prefers the term graphene) nanotube applications, the company produces a pre-dispersed concentrate – Tuball Matrix – that is said to provide uniform and permanent conductivity as well as maintaining or
28 COMPOUNDING WORLD | February 2019
mechanical performance. Uniform, permanent, stable and humidity-independent electrical conduc- tivity – all guaranteed by graphene nanotubes.” The new nanotube technology is able to avoid the common drawbacks in the usage of conven- tional antistatic additives, such as carbon black or ammonium compounds, in PVC plastisols. Applica- tion of carbon black usually affects mechanical performance, rules out colours and has a negative impact on rheology, while ammonium compounds can become unstable over time and provide only humidity-dependent resistivity. Another Tuball product in high market demand is
Matrix 801, which can be used for antistatic products produced by rotational moulding. “Just 0.7 wt.% of this graphene nanotube concentrate is enough to obtain a permanent and stable surface resistivity of 107
Ω/sq in coloured polyethylene tanks, while 1 wt.% of it achieves a surface resistivity of 106
Ω/sq in
black tanks for flammable and explosive liquids and powders,” Bolshakov says, adding that mechanical performance is also improved. “Recent developments include the preparation
of conductive LLDPE rotomoulded systems based on a low dosage of Tuball Matrix 801. This has allowed the replacement of typical carbon black compounds by new Tuball-based compounds providing equivalent electrical characteristics but with significantly better mechanical properties, including impact characteristics at low tempera- ture,” he says. According to Bolshakov, developing applica- tions in injection moulding, material enhancement and exploiting the synergistic effect of Tuball nanotubes with various fibres are the main targets of development for 2019. “We have already achieved a number of inspiring and highly promis- ing results in our own and in our partners’ labs,” he says. “The next steps are for us to scale the technol- ogy up and make it simple and economically viable for the industry.”
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PHOTO: OXCSIAL
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