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Search Publications by: Jan Obrzut (Fed)

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Displaying 76 - 100 of 113

Variations in Semiconducting Polymer Microstructure and Hole Mobility With Spin-Coating Speed

November 15, 2005
Author(s)
Dean M. DeLongchamp, Brandon M. Vogel, Youngsuk Jung, Curt A. Richter, Oleg A. Kirillov, Jan Obrzut, Daniel A. Fischer, S Sambasivan, Marc Gurau, Lee J. Richter, Eric K. Lin
Organic semiconductors permit low-cost processing methods such as spin-coating, dip coating, or ink-jet printing onto flexible substrates. However, the performance of these materials in devices is difficult to control and new processing methods can deliver

Non-Linear Charge Transport in Polythiophene Under High AC Field

January 1, 2005
Author(s)
Jan Obrzut, Tatiana Psurek, C. K. Chiang, Dean DeLongchamp
Complex impedance and conductivity were measured for regioregular poly(3-hexylthiophene) (P3HT) at alternating current (AC) voltages using a waveform technique. The waveforms were Fourier transformed from time domain to frequency domain and analyzed at

Extraordinary Flow Characteristics of Nanotube-Filled Polymer Materials

August 2, 2004
Author(s)
S B. Kharchenko, Kalman D. Migler, Jack F. Douglas, Jan Obrzut, E A. Grulke
Carbon nanotubes are under intense investigation due their potential for modifying the electrical conductivity (s), shear viscosity (h) and other transport properties of polymeric materials. They are hybrids of ordinary filler particles and nanoscale

High-Frequency Dielectric Relaxation in Trehalose-Glycerol Mixtures

February 1, 2004
Author(s)
O Anopchenko, Jan Obrzut, Bert W. Rust
Broadband dielectric measurements were performed on a series of trehalose-glycerol mixtures in a wide concentration range of glycerol and temperature swept from 220 K to 350 K. Relaxation spectra were obtained directly from the measured dielectric spectra

Non-Linear Transport Properties of Carbon Nanotube Filled Polypropylene

February 1, 2004
Author(s)
S B. Kharchenko, Kalman D. Migler, Jack F. Douglas, Jan Obrzut, E A. Grulke
Dispersal of a relatively small concentration [O(1%) volume fraction] of multiwall carbon nanotubes (MWNT) into polypropylene (PP) is found to cause large and complex changes in nanocomposite transport properties. Specifically, both the shear viscosity h(g

High Frequency Loss Mechanism in Polymers Filled With Dielectric Modifiers

November 1, 2003
Author(s)
Jan Obrzut, A Anopchenko, K Kano, Haonan Wang
We analyzed the high frequency dielectric relaxation mechanism in high-k composite materials using film substrates made of low loss organic resin filled with ferrolectric ceramics and with single wall carbon nanotubes (SWNT). The highest frequencey

Numerical Analysis of a Coaxial Line With a Complex Gap Capacitance

May 1, 2003
Author(s)
Jan Obrzut, O Anopchenko
A full wave numerical analysis was performed for a coaxial line terminated by a complex gap capacitance. The scattering parameters, input impedance and the spatial distribution of the electromagnetic field have been obtained in the frequency range of 100

Embedded Capacitance Materials and Their Application in High Speed Designs

March 1, 2003
Author(s)
T Bergstresser, R Hilburn, Jan Obrzut, K. M. Phillips
In this paper, we review three material options for embedded capacitors: thin FR4 epoxy-glass laminate, adhesiveless copper on polyimide substrate, and unsupported epoxy filled with high dielectric constant ceramic powder. Characteristics including

Optical Measurements of Structure and Orientation in Sheared Carbon-Nanotube Suspensions

March 1, 2003
Author(s)
Erik K. Hobbie, Haonan Wang, H W. Kim, Charles C. Han, E A. Grulke, Jan Obrzut
We describe an optical metrology for measuring shear-induced structure and orientation in dilute dispersions of multiwalled carbon nanotubes. Small-angle polarized light scattering and optical microscopy are combined in situ to quantify the structural

Broadband Dielectric Metrology for Polymer Composite Films

January 1, 2002
Author(s)
Jan Obrzut, N Noda, R Nozaki
Complex permittivity was measured at frequencies of 100 Hz to 10 GHz for films of polymer composites filled with ferroelectric ceramics. The frequency dependent dielectric constant and dielectric loss were fitted to a dielectric model expressed as a