Browsing by Author "Kim, Jong Dae"

Now showing 1 - 4 of 4
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    Incorporation of carbon nanotubes in epoxy polymer composites
    (2005) Kim, Jong Dae; Armeniades, C. D.
    The goal of this research was to develop and explore methods for incorporating Single-Walled Carbon Nanotubes (SWNTs) into polymer matrices, to form composites, in which the presence of SWNTs would improve significantly their mechanical properties, electrical conductivity, and thermal conductivity. We have used the concept of interpenetrating polymer networks (IPNs) for the design of our composites. One (preformed) network would consist of tangled SWNTs. It would be penetrated and swollen by the prepolymer molecules, which would polymerize in place, forming the second (interpenetrating) network. For the polymer matrix we chose epoxy resin systems, because of their chemical versatility, low setting stresses, and good mechanical properties. The main problem to be overcome was the very pronounced tendency of SWNTs to aggregate and the inability of polymerizable organic molecules to penetrate the aggregates and disperse the SWNTs. Several attempts to disperse SWNTs into an epoxy-acrylate system, specially formulated for low viscosity, using sonication energy were not successful. Neither were attempts to infuse epoxy prepolymer into the pores of bucky paper. A novel process was developed, which uses solvent in conjunction with sonication to disperse SWNTs into epoxy prepolymers, then divides the system into droplets that are sprayed into a heated chamber and deposited on a heated substrate. Control of the relative rates of solvent evaporation and polymerization/cure resulted in the formation of composites with dispersed SWNTs. Such composites, containing 1 wt. % SWNTs showed a drop in electrical resistivity of ca. 14 orders of magnitude (5.0 Ohm•m, compared to 2.0 x 1014 Ohm•m for pure epoxy). An efficient method for making SWNTs/epoxy/fiberglass composites was developed by incorporating SWNTs on the surface of fiberglass using the incipient wetting method. Small amount of SWNTs (0.1 wt. % of SWNTs) increased the flexural strength of the composites by 13%. This method can be extended to other fiber reinforcements such as Kevlar, carbon fiber, and ceramic fibers. SWNTs were chemically bridged both glass fiber and Epoxy matrix in the glass fiber/SWNTs/Epoxy composites. Fluorinated SWNTs (F-SWNTs) were chemically reacted with amine group active silane agent coated glass fiber. Chemically coated SWNTs-glass fiber was further reacted with Epoxy matrix. Surface analysis of chemically coated SWNTs/glass fiber confirmed the introduction of chemical bonding between glass fiber and F-SWNTs. (Abstract shortened by UMI.)
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    Polymer / carbon-nanotube interpenetrating networks and process for making same
    (2011-05-10) Armeniades, Constantine D.; Barrera, Enrique V.; Kim, Jong Dae; Rice University; United States Patent and Trademark Office
    The present invention is directed to new methods for combining, processing, and modifying existing materials, resulting in novel products with enhanced mechanical, electrical and electronic properties. The present invention provides for polymer/carbon nanotube composites with increased strength and toughness; beneficial for lighter and/or stronger structural components for terrestrial and aerospace applications, electrically and thermally conductive polymer composites, and electrostatic dissipative materials. Such composites rely on a molecular interpenetration between entangled single-wall carbon nanotubes (SWNTs) and cross-linked polymers to a degree not possible with previous processes.
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    Sidewall functionalization of carbon nanotubes with organosilanes for polymer composites
    (2013-09-24) Barrera, Enrique V.; Zhu, Jiang; Zhang, Lei; Khabashesku, Valery N.; Margrave, John L.; Kim, Jong Dae; Rice University; United States Patent and Trademark Office
    The present invention is directed to methods of functionalizing carbon nanotubes (CNTs), particularly single-wall carbon nanotubes (SWNTs), with organosilane species, wherein such functionalization enables fabrication of advanced polymer composites. The present invention is also directed toward the functionalized CNTs, advanced CNT-polymer composites made with such functionalized CNTs, and methods of making such advanced CNT-polymer composites.
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    Smart materials: strain sensing and stress determination by means of nanotube sensing systems- composites- and devices
    (2010-06-01) Barrera, Enrique V.; Nagarajaiah, Satish; Dharap, Prasad; Zhiling, Li; Kim, Jong Dae; Rice University; United States Patent and Trademark Office
    The present invention is directed toward devices comprising carbon nanotubes that are capable of detecting displacement, impact, stress, and/or strain in materials, methods of making such devices, methods for sensing/detecting/monitoring displacement, impact, stress, and/or strain via carbon nanotubes, and various applications for such methods and devices. The devices and methods of the present invention all rely on mechanically-induced electronic perturbations within the carbon nanotubes to detect and quantify such stress/strain. Such detection and quantification can rely on techniques which include, but are not limited to, electrical conductivity/conductance and/or resistivity/resistance detection/measurements, thermal conductivity detection/measurements, electroluminescence detection/measurements, photoluminescence detection/measurements, and combinations thereof. All such techniques rely on an understanding of how such properties change in response to mechanical stress and/or strain.