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THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING
GEORGIA INSTITUTE OF TECHNOLOGY
Under the provisions of the regulations for the degree
DOCTOR OF PHILOSOPHY
on Tuesday, December 1, 2020
9:30 AM
via
Bluejeans Video Conferencing
https://bluejeans.com/428601647
will be held the
DISSERTATION DEFENSE
for
Pedro J. Arias-Monje
“Advanced Dispersion Strategies of Carbon Nanofillers and their use to enhance Mechanical and Electrical Properties of Polyacrylonitrile Fibers”
Committee Members:
Prof. Satish Kumar, Advisor, MSE
Prof. Karl Jacob, MSE
Prof. Hendrik Heinz, ChBE, UCB
Prof. Kyriaki Kalaitzidou, ME
Prof. Suresh Sitaraman, ME
Prof. Naresh Thadhani MSE
Abstract:
This study focuses on making next generation of polyacrylonitrile fibers containing carbon nanofillers, namely carbon nanotubes (CNTs) and carbon black (CB). Mechanically strong and electrically conducting poly(acrylonitrile) (PAN) fibers were obtained by incorporating up to (a) 15 wt% single wall carbon nanotubes (SWNTs) and (b) 15 wt% carbon black (CB) and 2 wt% multiwall carbon nanotubes (MWNTs). These fibers with tensile modulus of up to 32.1 GPa and electrical conductivity of 2.2 S/m rival some intrinsically electrically conducting polymer fibers without doping. Nanocomposite carbon fibers with up to (a) 25 wt% SWNTs and (b) 24 wt% carbon black and 3 wt% MWNTs were also produced, and it is shown that CNT inclusion improves tensile modulus, while the inclusion of CB can be used to lower the carbon fiber cost, while lowering the mechanical properties. Stretchable PAN fibers with up to 60 wt% CB were also produced by increasing the diameter of the CB particles.
Fibers with high SWNT loading of 15 wt% were possible by wrapping the SWNTs with poly(methyl methacrylate) (PMMA). The mechanism of PMMA wrapping of SWNTs was studied experimentally and theoretically (using molecular dynamic simulation). It is shown that PMMA wrapping can be used to increase filler-matrix interaction in the polymer fiber. It is further shown that PMMA wrapping is not detrimental to the filler-matrix interaction in the resulting carbon fiber. This is despite the fact that PMMA does not have carbon yield.
Effect of the carbon nanotubes and carbon black fillers on PAN solution/dispersion rheology has been studied. The effect of these fillers on fiber processability and fiber structure is also comprehensively studied. Research also includes stabilization and carbonization of the conductive CB/PAN nanocomposite fibers via Joule Heating to obtain low-cost carbon fibers.
