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TUBALL single wall nanotubes offer cost-effective solutions


Due to their extremely high aspect ratio, single wall carbon nanotubes provide excellent conductivity characteristics while avoiding the negative impact on mechanical and other properties traditionally required by widely used conductive additives such as carbon black. Dispersion challenges, the last major roadblock to single wall carbon nanotube adoption, have finally been solved with a new line of nanotube super concentrates that are already being used by large industrial manufac- turers and open the door to superior conductivity for all material producers.


The most widely-used additive for production of electrically conductive polymer compounds currently on the market is carbon black, due to its high-performance and low price. How- ever, the high concentration required in compounds – up to 30% – has always been a key issue for manufacturers as it leads to a difficulties such as changes in processing behaviour, negative impact on colour, fluidity and density, degradation of surface smoothness, and a reduction in the mechanical strength of materials. Furthermore, most of the conductive additives available suffer problems in terms of poor or uneven dispersion and cannot provide uniform conductivity throughout the compound matrix, so manufacturers often face the widespread phenomenon of “hot spots.” This can have a negative effect on productivity, product reliability, manufacturing profitability and employee safety.


The carbon black alternative The discovery of carbon nanotubes (CNTs) was expected to bring about a new generation of conductive additives, due to their high conductivity but without the negative impact on the materials that is usually associated with carbon black. However, it was soon discovered that multi wall carbon nanotubes (MWCNTs) and single wall carbon nanotubes (SWCNTs), despite their similar nature, exhibit huge differ- ences in processing and performance characteristics. For instance, the low mean outer diameter and extremely high


Figure 1: Comparison of loading levels of various carbon-based additives required to achieve conductivity in unfilled polyester resin


aspect ratio of SWCNTs lead to a low percolation threshold; an interconnecting conductive network of SWCNTs can be formed throughout the material matrix at extremely low concentrations, starting from just 0.01% of the total weight. In contrast, achieving the same conductivity characteristics with MWCNTs would typi- cally require a concentration 10 to 20 times higher, while conductive carbon black would require a concentration 100 times higher. The high performance of SWCNTs is due to their structure and exceptional characteristics; they are 100 times stronger than steel, are thermally stable up to 1,000°C, provide a length to diameter ratio of around 5000, are one of the best electrical conductors available (and are five times lighter than copper).


Applying research to industry Ultra-low loadings of SWCNTs are sufficient to create a uniform 3D network in a material matrix that is both conduc- tive and strengthening. This cannot be achieved with any other carbon additive at a similar loading level. Despite the evident advantages of SWCNTs as a conductive additive, until


recently they have not achieved wide- spread application. This is due to a number of factors, including high price and low volumes of production. However, the most significant problem has been the lack of simple and cost-effective technologies for introducing nanotubes into the material matrix. OCSiAl is the world’s largest producer of SWCNTs, having established the first scalable production technology. It is now supplying its TUBALL nanotube-based products on an industrial scale, and has taken the lead in the creation of tech- niques for introducing nanotubes into material matrixes. This includes the introduction of the first-ever super concentrates – TUBALL MATRIX. Launched this year, the TUBALL MATRIX SWCNT-based super concentrates provide materials with uniform electrical conductivity in the range of 108


–102


Ω·cm without compromising the original colour or mechanical properties of the product.


TUBALL MATRIX benefits One of the key benefits of TUBALL MATRIX is uniform and permanent electrical conductivity, which can be


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