Marisabel Kelly (Lebrón-Colón) - Academia.edu (original) (raw)

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Papers by Marisabel Kelly (Lebrón-Colón)

Journal of Electroanalytical Chemistry, Sep 1, 2013

Carbon, Feb 1, 2011

... Chem Rev, 98 5 (1998), pp. 1787–1802. [8] E. Antunes, A. Lobo, E. Corat, V. Trava-Airoldi, A ... more ... Chem Rev, 98 5 (1998), pp. 1787–1802. [8] E. Antunes, A. Lobo, E. Corat, V. Trava-Airoldi, A ... 71–81. [10] J. Aladekomo and R. Bragg, Structural transformations induced in graphite by grinding: analysis of 002 X-ray diffraction line profiles. Carbon, 2 6 (1990), pp. 897–906. ...

A significant improvement in the mechanical properties of the thermoplastic polyimide film was ob... more A significant improvement in the mechanical properties of the thermoplastic polyimide film was obtained by the addition of noncovalently functionalized single-wall carbon nanotubes (SWNTs). Polyimide films were reinforced using pristine SWNTs and functionalized SWNTs (F-SWNTs). The tensile strengths of the polyimide films containing F-SWNTs were found to be approximately 1.4 times higher than those prepared from pristine SWNTs.

Physica Status Solidi (rrl), Aug 1, 2012

• Supercapacitors will be critical for future hybrid electric large aircraft where the combinatio... more • Supercapacitors will be critical for future hybrid electric large aircraft where the combination of gas turbine engine and energy storage device will achieve greater than 75 % reduction in fuel burn to meet Subsonic Fixed Wing N+3 goals.

2022 IEEE 4th International Conference on Dielectrics (ICD), Jul 3, 2022

ACS Applied Materials & Interfaces, 2013

We report the functionalization of carbon nanotubes with two azobenzene-based chromophores with l... more We report the functionalization of carbon nanotubes with two azobenzene-based chromophores with large internal dipole moments and opposite dipole orientations. The molecules are attached to the nanotubes non-covalently via a pyrene tether. A combination of characterization techniques shows uniform molecular coverage on the nanotubes, with minimal aggregation of excess chromophores on the substrate. The large on/off ratios and the subthreshold swings of the nanotube-based field-effect transistors (FETs) are preserved after functionalization, and different shifts in threshold voltage are observed for each chromophore. Ab initio calculations verify the properties of the synthesized chromophores and indicate very small charge transfer, confirming a strong, non-covalent functionalization.

Exfoliated hexagonal boron nitride (hBN)/alumina composite can be fabricated by following the pro... more Exfoliated hexagonal boron nitride (hBN)/alumina composite can be fabricated by following the process of (1) heating a mixture of hBN, AlCl3, and NaF in nitrogen for intercalation; (2) heating the intercalated product in air for exfoliation and at the same time converting the intercalate (AlCl3) into Al2O3, (3) rinsing the oxidized product, (4) coating individual exfoliated hBN platelets that contain Al2O3 with new layers of aluminum oxide, and finally, (5) hot pressing the product into the composite. The composite thus obtained has a composition of approximately 60 percent by weight hBN and 40 percent by weight alumina. Its in-plane and through-plane thermal conductivity were measured to be 86 and 18 watts per meter Kelvin, respectively, at room temperature.

The development of nanostructured materials can lead to systems with significantly enhanced prope... more The development of nanostructured materials can lead to systems with significantly enhanced properties over conventional materials. Use of nanostructured materials in aerospace applications can lead to substantial reductions in critical vehicle weight and improvements in durability and performance. Research at NASA Glenn Research Center in the development of nanostructured materials for aerospace power and propulsion systems has led to new materials with considerable promise towards achieving desired weight, safety and performance requirements for future NASA aeronautics and space exploration missions

High specific power density, megawatt-scale electric machines (motors and generators) are needed ... more High specific power density, megawatt-scale electric machines (motors and generators) are needed to enable megawatt-scale electric aircraft propulsion systems for single-aisle aircraft. Thermally insulating electrical insulation materials in the stator windings limits the ability to thermally manage the heat produced in these machines. Polymer-ceramic composites along with novel processing techniques offer viable options to improve the thermal conductivity of the electrical insulation system. This paper outlines current National Aeronautics and Space Administration's Glenn Research Center efforts of developing several polymer-ceramic systems and processing techniques as they relate to electric machine insulation (including potting). There is also analysis of how these factors relate to machine performance.

Dielectric analysis (DEA) is a thermal analysis technique primarily developed to optimize polymer... more Dielectric analysis (DEA) is a thermal analysis technique primarily developed to optimize polymer cure profiles in manufacturing facilities to reduce scrap and to diagnose insulation. The recent implementation of this technique to characterize the behavior of new in-house electrical insulation formulations has been advantageous in providing a better understanding of insulation exposed to thermal and electrical stresses at their anticipated operating temperatures and frequencies. Because the dielectric properties of in-house high-voltage insulation formulations are not well understood, DEA was initially carried out using a wellestablished commercially available polyimide film. This report documents the findings from using dielectric thermal analysis to characterize the electrical properties of commercially available polyimide films and in-house polyimide composite formulations that were exposed to environments anticipated in high-voltage electric motors. The effects of moisture content and thermal aging on the dielectric properties of commercial polyimide are also reported. Information presented in this paper illustrates that DEA can be used as a viable technique to screen candidates for new electrical insulation.

Journal of the American Ceramic Society, 2016

Hexagonal BN is an unusual material in that it is both highly thermally conductive as well as an ... more Hexagonal BN is an unusual material in that it is both highly thermally conductive as well as an electrical insulator. Additionally, hBN is also thermally stable in air. This unusual combination of properties makes hBN of significant interest for thermal management. Unfortunately, hBN is not easily consolidated into substrates without the addition of second phases which generally result in poorer thermal performance. This research investigates the potential to utilize this material to dissipate heat from high-voltage, high-power electrical devices. Specifically, a process to coat individual platelets of commercial hexagonal BN powder with a layer of amorphous aluminum oxide was developed. The coated hexagonal BN was then hot-pressed to form a highly thermally conductive substrate. The process to coat hexagonal BN platelets with aluminum oxide was accomplished by mixing hexagonal BN with AlCl 3 containing some water, then evaporation of excess AlCl 3 to form a Al, Cl, and O layer on hexagonal BN. This product was then heated in air to convert the surface layer into aluminum oxide. Following hot pressing to 1950°C and 10 ksi, the consolidated composite has through-plane and in-plane thermal conductivity of 14 and 157 WÁ(mÁK)-1 , respectively, at room temperature.

Synthetic Communications, 1998

Nanotechnology, 2012

We report for the first time a novel room temperature methane (CH(4)) sensor fabricated using por... more We report for the first time a novel room temperature methane (CH(4)) sensor fabricated using porous tin oxide (SnO(2)) nanorods as the sensing material. The porous SnO(2) nanorods were synthesized by using multiwall carbon nanotubes (MWCNTs) as templates. Current versus time curves were obtained demonstrating the room temperature sensing capabilities of the sensor system when exposed to 0.25% CH(4) in air. The sensor also exhibited a wide temperature range for different concentrations of CH(4) (25-500 °C), making it useful in harsh environments as well.