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Displaying 1701 - 1725 of 1882

Tri-Alpha-Napthyl Benzene as a Crystalline or Glassy Matrix for Matrix-Assisted Laser Desorption/Ionization: A Model System for the Study of Effects of Dispersion of Polymer Samples at a Molecular Level

January 1, 2002
Author(s)
Barry J. Bauer, Kathleen M. Flynn, Da-Wei Liu, William R. Blair
Tri-a-napthyl benzene (TaNB) is used as a matrix in matrix-assisted laser desorption/ionization (MALDI) spectroscopy. Electrosprayed TaNB is crystalline and has a melting point of 180 2 C. After heating above the melting point, TaNB becomes amorphous with

Variation of Electrical Properties With Exfoliation Condition in Nanocomposites

January 1, 2002
Author(s)
M M. McBrearty, Anthony J. Bur, S C. Roth
Dielectric measurements were made on clay filled nylon and polyethylene-ethyl vinyl acetate (PE-EVA) copolymer nanocomposites during processing by extrusion. Nylon without clay had a small dielectric dispersion while PE-EVA did not. The addition of natural

Convalent Cationization Method for the Analysis of Polyethylene by Mass Spectrometry

December 1, 2001
Author(s)
Barry J. Bauer, William E. Wallace, B M. Fanconi, Kathleen M. Flynn
Polyethylene and other polyolefins have not been amenable to mass spectrometric characterization of molecular mass distribution due to the ineffectiveness of conventional methods of cationization. The lack of polar groups, unsaturation, and aromaticity

Dispersion and Nucleating Effects of Clay Fillers in Nanocomposite Polymer Films

December 1, 2001
Author(s)
V Ferreiro, G Schmidt, Charles C. Han, Alamgir Karim
Nanocomposite polymeric materials offer unique properties such as mechanical, electrical, thermal, etc. Such property enhancements are induced not only by the physical presence of the filler but also by the interaction of the polymer with the filler and

Interfacial Shear Strengths of Dental Resin-Glass Fibers by the Microbond Test

November 1, 2001
Author(s)
Walter G. McDonough, Joseph M. Antonucci, Joy Dunkers
In this study, the feasibility of using the microbond test (MBT) to probe the durability of the bond between a dental resin with differently silanized E-glass fibers was investigated. The E-glass fibers were silanized with equivalent amounts of two types

Time-Resolved Isothermal Crystallization of Absorbable PGA-co-PLA Copolymer by Synchrotron Small-Angle X-Ray Scattering and Wide-Angle X-Ray Diffraction

October 1, 2001
Author(s)
Z G. Wang, X H. Wang, B S. Hsiao, S Andjelic, D Jamiolkowski, J McDivitt, J Fischer, J Zhou, Charles C. Han
The isothermal crystallization behavior of absorbable dyed and undyed PGA-co-PLA copolymers was investigated by time-resolved simultaneous synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) methods. The morphological

MSEL FY 2001 Programs and Accomplishments: Polymers Division

September 1, 2001
Author(s)
B M. Fanconi, Eric J. Amis
The Polymers Division provides measurement methods, standards, and concepts to facilitate technology development, manufacture of products, commerce, and use of synthetic polymers. Projects are selected based on assessments of current needs and in

Combinatorial Investigations of Polymer Adhesion

August 1, 2001
Author(s)
A J. Crosby, Alamgir Karim, Eric J. Amis
Combinatorial measurement methods allow material properties to be investigated in a multivariable space. These techniques could be especially attractive for investigating polymer adhesion that is determined by the complex coupling of bulk and interfacial

High Throughput Approach to Crystallization in Thin Films of Isotactic Polystyrene

August 1, 2001
Author(s)
Kathryn L. Beers, Jack F. Douglas, Eric J. Amis, Alamgir Karim
The dependence of the crystallization rate of isotactic polystyrene was measured as a function of film thickness and temperature on films with continuous gradients. The results agreed with literature values obtained on discrete films. This validates the

Small Angle Neutron Scattering Study on Polymer-Clay Solutions

August 1, 2001
Author(s)
Charles C. Han, G Schmidt, A Nakatani, Paul D. Butler
The objective of this work is to investigate the influence of shear on the structure of a highly viscoelastic, aqueous polymer-clay solution. Many structural models have been proposed for such systems. However, this is the first time to observe the

Polymer Chain Relaxation: Surface Outpaces Bulk

July 1, 2001
Author(s)
William E. Wallace, Daniel A. Fischer, K Efimenko, Wen-Li Wu, Jan Genzer
In this work we show how carbon near-edge X-ray absorption fine structure (NEXAFS) can be applied to detect both surface and bulk segmental relaxation in uniaxially deformed polystyrene samples. We demonstrate that by simultaneously monitoring the partial
Displaying 1701 - 1725 of 1882