Visualizing Current Pathways for the Evaluation and Improvement of the CNT-Polymeric Composite Properties

At AIST, our mission is to bring or “bridge” invention with industry and to contribute to society through the development of new technologies. With this in mind, over the past few years, our team has placed significant effort in developing carbon nanotube (CNT)-polymeric composites, mainly rubber and resin, using our proprietary “Super Growth” CNTs [1] and other commercially available single and multi-walled CNTs. Thus far, we have reported the successful development and commercialization of CNT rubber composites (O-rings) possessing long lifetime, high heat resistance, and high-pressure resistance [2] as well as CNT resin composites exhibiting excellent heat resistance and impact resistance using PEEK, a super engineering plastic [3]. The development of these fabrication technologies enables application of these materials in manufacturing and mainstream uses. In this way, we are able to fulfil our mission to contribute the development of materials and technologies for the betterment of society.<br/>To best design the material to possess the required mechanical, electrical, or thermal properties, understanding of the pertinent governing mechanisms is necessary. Furthermore, the nature of the CNT dispersion in the composite matrix is well known to have significant effect on the formation of a 3-D network structure, i.e., percolation, but evaluation of the dispersion state within a composite for a nano-sized filler is challenging.<br/>In this presentation, I will show CNT rubber/resin composites that we have developed and put to practical use, as well as evaluation techniques we have used to visualize and understand the dispersion of CNTs in these composites. Specifically, I will introduce an analysis method using actual rubber/resin composites, focusing on lock-in heat analysis [4-6] and nano-indentation [7]. Through this approach, the homogeneity of the dispersion within the rubber can be characterized through the visualization of the distribution in current pathways. I will show how the application of this these characterization techniques aids in the property improvement of our fabricated composites.<br/> <br/>[1] K. Hata, D. N. Futaba, et al. Science 306, 1362 (2004).<br/>[2] S. Ata, et al. Nano Letters 12, 2710 (2012).<br/>[3] S. Ata, et al. Polymer 176, 60 (2019).<br/>[4] T. Morimoto et al., Scientific Reports (2019).<br/>[5] B. Thi et al., Carbon (2019).<br/>[6] H. Nakajima et al., Science Advances (2019).<br/>[7] N. Matsumoto et al. in preparation.