Type of Document	Dissertation
Author	Yeh, Cherng-Shii
URN	etd-11192007-121847
Title	A Study of Nanostructure and Properties of Mixed Nanotube Buckypaper Materials: Fabrication, Process Modeling, Characterization and Property Modeling
Degree	Doctor of Philosophy
Department	Industrial and Manufacturing Engineering, Department of
Advisory Committee	Advisor Name Title Zhiyong Liang Committee Chair Ben Wang Committee Member Chuck Zhang Committee Member David Jack Committee Member
Keywords	Carbon Nanotubes Buckypaper Statistical Analysis Uniformity Surface Area Electrical Conductivity
Date of Defense	2007-11-14
Availability	unrestricted
Abstract Single-walled carbon nanotube buckypaper (SBP) is a thin film of preformed nanotube networks that possesses many excellent properties. SBP is considered to be very promising in the development of high-performance composite materials; however, the high cost of single-walled nanotubes (SWNTs) limits industrial applications of SBP materials. Mixed buckypaper (MBP) is a more affordable alternative that combines SWNTs with low-cost multi-walled nanotubes (MWNTs) or carbon nanofibers (CNFs) to retain most of the excellent properties of SBP while significantly reducing the cost. This study proposes a manufacturing process of MBPs. The process parameters were studied through experimental design and statistical analysis. The parameters included mixing material type, mixing ratio, sonication effect, surfactant amount, and cleaning effect. The effects of the parameters on nanostructure uniformity, purity, Brunauer-Emmett-Teller (BET) surface area and electrical conductivity of the resultant MBPs were revealed. Results of the study show that all those parameters and their interactions are influential to the dispersion and uniformity of nanostructure and purity, but only mixing material type and ratio are influential to the BET surface area and electrical conductivity. To systematically reveal the process-nanostructure-property relationship of SBP and MBP materials, the nanostructures of the buckypapers were characterized as rope size, length and pore size distributions of the nanomaterials in resultant buckypapers. These distributions featured bimodal phenomenon due to different material mixtures; therefore, the distributions were further separated into two individual ones and fitted into Weibull distributions. Two nanostructure-property models of buckypaper materials were developed. The specific surface area model was built upon the characterization and analysis of buckypaper nanostructures. The model showed that rope size distribution and mixed ratio of nanomaterials are governing factors for the resultant specific surface area of buckypaper. The electrical conductivity model captured multiscale electrical transport phenomenon of nanotube networks in buckypapers. The model considered chirality, contact area, contact type, diameter, length and orientation distributions of nanotubes in buckypapers. The proposed models not only can predict property trends correctly, but can also reveal the critical process-nanostructure-property relationships of buckypaper materials. The results are important for the further tailoring and optimization of the manufacturing process and properties of nanotube buckypapers.
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