Theoretical and Empirical Aproaches to Fabricating Ultrahigh Strength Carbon Nanotube Yarns

Abstract

The purpose of this study is to fabricate ultrahigh-strength carbon nanotube yarns <br/> (CNTYs) for which the mechanical properties exced those of conventional high- performance fibers through theoretical and empirical aproaches for manufacturing <br/> high-strength CNTYs. Due to the inherently superb mechanical properties and high <br/> aspect ratios of CNTs, eforts to produce ultrahigh-strength CNTYs which properties <br/> that exced those of conventional high-strength fibers such as carbon fibers have <br/> continued over the last few decades. As a result, a variety of CNTY fabrication methods <br/> have ben developed since the early 200s up to the present, and it is now posible to <br/> produce continuous CNTYs with these methods. Nevertheles, macroscale CNTYs stil <br/> fail to exhibit he excelent mechanical performance of nanoscale individual CNTs. To overcome these limitations, various atempts to improve the mechanical strength of <br/> CNTYs have recently ben proposed. The mechanical and electrical properties of CNTs <br/> difer depending on certain aspects of the nanostructure, such as the length, number of <br/> wals, and the diameter of the nanotubes. In aditon, the microstructure of the CNT <br/> asembly is closely related to the mechanical and electrical properties of the asembly. <br/> Therefore, the most important isue is to control the nanostructure of CNTs and the <br/> microstructure of the CNT asembly in order to fabricate ultrahigh-strength CNTYs.<br/> Chapter 1 briefly describes the CNTYs and related factors that afect he mechanical <br/> properties of yarns. The purpose of this study is to review recent studies on improving <br/> these mechanical properties and to uncover isues and solutions that are thus far <br/> unresolved.<br/> Chapter 2 introduces and presents the atempts made to derive the theoretical <br/> corelation betwen the structure and the CNTY strength based on the failure mechanism <br/> of CNTYs. First, the relationship betwen the structural parameters of the nanostructures <br/> of individual CNTs, the basic constiuents of yarns, and the mechanical strength of the <br/> CNTYs is investigated. The efect of the microstructure of the CNT asembly on the <br/> strength of CNTYs is then theoreticaly considered.<br/> Chapters 3 and 4 discus the influence of the structural factors of CNTs as derived <br/> from chapter 2 on the yarn strength. The efect of the nanostructure of the carbon <br/> nanotubes on the mechanical properties of CNTYs is investigated by undertaking the <br/> synthesis CNTYs made of CNTs with various nanostructures, after which the efects of <br/> polymer chains on the internal structures of CNTYs and the yarn deformation behaviors <br/> are studied.<br/> Finaly, chapter 5 discuses developments related to ultrahigh-strength CNTYs <br/> through croslinking considering the nanostructures and microstructures of CNTs based <br/> on the theoretical and empirical understanding presented in the previous chapter.<br/>