SouthWest NanoTechnologies (SWeNT) has developed two new grades in its SMW™ line of Specialty Multi-wall CNT. These materials are used as additives that enable higher electrical conductivity in polymer compounds and improved cathode performance in Lithium Ion batteries.
The new grades, SMW200 and SMW210 have demonstrated the greatest ease of dispersions and lowest percolation threshold of any MWCNT product in multiple customer thermoplastic compound evaluations. This enables ESD (electrostatic discharge) performance at lower filler loadings than either Carbon Black or other Multi-wall CNT, in a variety of polymers. This low percolation threshold minimizes the degradation of physical properties of the polymer, a common problem in heavily loaded compounds, and higher conductivity at comparable loading broadens the range of applications for conductive polymer compounds. Additionally, SMW200 compounds have been shown to have improved mechanical properties when compared to other MWCNT.
Both materials are synthesized by the CoMoCAT method, widely recognized as producing the most consistent CNT products, and for its scalability. Both materials disperse easily into most polymers and have the same ultra-pure, defect-free, less entangled CNT. SMW200 is a "purified" grade, with CNT purity of 96%+ (even higher purity research grades are available upon special request). SMW210 is an "as produced" grade, with CNT purity of 70%+, with the balance being mainly metal oxides used in the catalyst.
Because post-synthesis purification is not done for SMW210, the pricing is much lower.SMW210 has a hybrid structure with metal-oxide particles attached to the CNT, improving dispersion still further, at a much lower cost. In thermoplastic compounds, there is little performance difference between SMW200 and SMW210 with respect to ease of dispersion, conductivity and percolation, with most customers choosing SMW210 due to lower cost.
SMW200 has also been demonstrated as a Carbon Black replacement in Lithium Ion battery cathodes. Very low loadings (1 wt %) of SWM200 have resulted in doubled cycle life, higher capacity, lower heat build-up and better low temperature performance.
"We have already generated a great deal of customer interest in these materials, and resulting demand is driving us to increase capacity," says SWeNT CEO David Arthur. "We have just shipped our first 100 kg of SMW210 for a customer's full-scale qualification trial for a high-volume conductive polymer application. Also, several Li-ion battery manufacturers are testing SMW200 now (this higher purity grade may be required for certain applications like batteries). To meet anticipated demand in 2013, SWeNT is adding capacity of multiple tonnes per month."