Type of Document	Thesis
Author	Hossieny, Nemat J.
Author's Email Address	nematnejad@gmail.com
URN	etd-01062010-162530
Title	Morphology and Properties of Polymer/Carbon nanotube Nanocomposite Foams prepared by Super critical Carbon dioxide
Degree	Master of Science
Department	Industrial and Manufacturing Engineering, Department of
Advisory Committee	Advisor Name Title Changchun Zeng Committee Chair Tao Liu Committee Member Zhiyong Liang Committee Member
Keywords	Polymer Nanocomposite Foams Microcellular Foams Carbon Nanotubes
Date of Defense	2009-12-01
Availability	unrestricted
Abstract Poly(methyl methacrylate) (PMMA) multi-walled carbon nanotubes (MWCNTs) nanocomposites were synthesized by several methods using both pristine and surface functionalized carbon nanotubes (CNTs). Fourier transform infrared (FTIR) spectroscopy was used to characterize the presence and types of functional groups in functionalized CNTs, while the dispersion of CNTs in PMMA was characterized using scanning electron microscopy (SEM). The prepared nanocomposites were foamed using carbon dioxide (CO2) as the foaming agent. The cell morphology was observed by SEM, and the cell size and cell density were calculated via image analysis. It was found that both the synthesis methods and CNTs surface functionalization affect the CNTs dispersion in the polymer matrix, which in turn profoundly influences the cell nucleation mechanism and cell morphology. The CNTs are efficient heterogeneous nucleation agents leading to increased cell density at low particle concentrations. A mixed mode of nucleation mechanism was observed in nanocomposite foams in which polymer rich and particle rich region co-exist due to insufficient particle dispersion. This leads to a bimodal cell size distribution. Uniform dispersion of CNTs can be achieved via synergistic combination of improving synthesis methodology and CNT surface functionalization. Foams from these nanocomposites exhibit single modal cell size distribution and remarkably increased cell density and reduced cell size. An increase in cell density of ~70 times and reduction of cell size of ~80% was observed in nanocomposite foam with 1% CNTs. The effect of CNT surface functionalization on the tensile properties of the PMMA/MWNT nanocomposite and nanocomposite foams were noticed. An increase of ~60% in elastic modulus and ~40% increase in the tensile strength was observed in nanocomposite foam with 0.5 % functionalized CNTs.
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