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Displaying 1651 - 1675 of 1882

Viscoelastic Characterization of Sealant Materials

September 18, 2002
Author(s)
Donald L. Hunston, Christopher C. White
Polymeric sealants are an important example of a major consumer product where the performance depends critically on rheological properties. The work here developed a testing and modeling procedure to characterize the basic mechanical properties of sealant

MALDI MS Characterization of Covalent Cationized Polyethylene

August 1, 2002
Author(s)
Sheng Lin-Gibson, D L. Brunner, David L. VanderHart, Barry J. Bauer, B M. Fanconi, Kathleen M. Flynn, William E. Wallace
Polyolefins, saturated hydrocarbon polymers such as polyethylene (PE) and polypropylene, are, by production volume, the most widely used of all A new method for the mass spectrometry of saturated polyolefins whereby an organic cation is covalently bonded

MeasuringThe Modulus of Polymer Films by Strain-Induced Buckling Instabilities

August 1, 2002
Author(s)
Christopher M. Stafford, C Harrison, Alamgir Karim, Eric J. Amis
We present a high-throughput technique for measuring the Young s modulus of thin polymer films. This technique exploits a strain-induced buckling instability observed in films supported on elastomeric substrates. By employing a combinatorial polymer film

Optimizing the Covalent Cationization Method for the Mass Spectrometry of Polyolefins

August 1, 2002
Author(s)
Sheng Lin-Gibson, L Brunner, David L. VanderHart, Barry J. Bauer, B M. Fanconi, Charles M. Guttman, William E. Wallace
Previously a new method was introduced for the mass spectrometry of polyolefins whereby an organic cation is covalently bonded to the polymer to produce the necessary ionization for the creation of intact gas?phase macromolecules by matrix-assisted laser

Polymer Science at the NIST Combinatorial Methods Center

August 1, 2002
Author(s)
Cher H. Davis, Kathryn L. Beers, Aaron M. Forster, Christopher M. Stafford, A P. Smith, C Harrison, Weiping Zhang, Alamgir Karim, Eric J. Amis
The measurements, standards, and test methods developed by NIST, in partnership with other organizations, often help unlock the potential of new discoveries and budding technologies. Combinatorial methods are a textbook example. These emerging tools can

Reaction Front Induced Roughness in Chemically Amplified Photoresists

August 1, 2002
Author(s)
Vivek Prabhu, Ronald L. Jones, Eric K. Lin, Joseph~undefined~undefined~undefined~undefined~undefined Lenhart, Christopher Soles, Wen-Li Wu, D L. Goldfarb, M Angelopoulos
We have examined, with tapping mode atomic force microscopy(AFM), the effect of post-exposure bake times and developer on surface roughness using model bilayer interfaces of deuterium-labeled poly(tert-butyloxycarbonyloxy styrene) and poly(hydroxystyrene)

Rheology of Poly(ethylene oxide) Clay Solutions

August 1, 2002
Author(s)
Sheng Lin-Gibson, G Schmidt, Jai A. Pathak, Charles C. Han
Poly(ethylene oxide) and Laponite, a synthetic hectorite clay, form highly viscoelastic solutions in water. Above a certain clay concentration, these solutions can be described as physical crosslinked networks where clay platelets undergo equilibrium

Structure Formation in Micro-Confined Polymeric Emulsions

August 1, 2002
Author(s)
Jai A. Pathak, Steven D. Hudson, Kalman D. Migler
Application of a shear field to a concentrated emulsion induces a complex spatial and temporal response. The behavior of a concentrated system is treated as an extrapolation of the well-understood behavior of isolated droplets (or of the behavior of two

Advanced Numerical Methods for Polymer Mass Spectral Data Analysis

July 1, 2002
Author(s)
William E. Wallace, Charles M. Guttman, Anthony J. Kearsley, Javier Bernal
A mathematical algorithm is presented that accurately locates and calculates the area beneath peaks using only reproducible mathematical operations and a single user-selected sensitivity parameter.

Chemical Ionization of Saturated Hydrocarbons Using Organometallic Ion Chemistry

July 1, 2002
Author(s)
H M. Byrd, Charles M. Guttman, D P. Ridge
Introduction: The potential for quick and direct measurement of chemical composition, absolute molecular mass (MM), MM distribution of linear and branched saturated polyolefins makes mass spectrometry especially attractive to the polymer industry. However

Quantitation of Polymer End Groups Using MALDI TOF MS

July 1, 2002
Author(s)
A P. Weaver, Charles M. Guttman, Kathleen M. Flynn
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) has been employed to analyze polystryrene mixtures of molecular mass ca. 4000u. The component polymers of thes mixtures are identical except for their end groups

A Microshear Test to Measure Bond Strengths of Dentin-Polymer Interfaces

June 1, 2002
Author(s)
Walter G. McDonough, Joseph M. Antonucci, J He, Y Shimada, Martin Y. Chiang, Gary E. Schumacher, Carl R. Schultesiz
Mechanical property tests such as the diametral tensile, uniaxial tensile and transverse strength tests are commonly used in studying the interfacial properties of the bond between dental composites and dental substrates such as dentin and enamel. These

Dispersion of Functionalized Nanoclay Platelets in an Amine-Cured Epoxy Resin System

June 1, 2002
Author(s)
D T. Raghavan, E Feresenbet, D Yebassa, A Emekalam, Gale A. Holmes
Nanocomposites are a relatively new class of materials obtained by dispersing montmorillonite clay in polymer matrix. Evidences from literature suggest that clay platelet dispersion during nanocomposite preparation and clay-matrix adhesion are major

Growth Pulsations in Symmetric Dentritic Crystallization in Thin Polymer Blend Films

May 1, 2002
Author(s)
V Ferreiro, Jack F. Douglas, James A. Warren, Alamgir Karim
The crystallization of polymeric and metallic materials normally occurs under conditions far from equilibrium, leading to patterns that grow as propagating waves into the surrounding unstable fluid medium. The Mullins-Sekerka instability causes these wave

In-Line Dielectric Monitoring During Extrusion of Filled Polymers

May 1, 2002
Author(s)
Anthony J. Bur, S C. Roth, M M. McBrearty
Dielectric measurements were made on clay filled polyethylene-ethyl vinyl acetate (EVA) copolymer nanocomposites during processing by extrusion. The results show that composites containing chemically treated clays display significant dielectric dispersions

Shift in Polymer Blend Phase-Separation Temperature in Shear Flow

May 1, 2002
Author(s)
Jack F. Douglas
Recent experimentalstudiesof polymer blendsin simple shear flow have indicated large *Shih of the apparent phase-separation temperature. These shifts are examined within the context of a nonequilibrium hydrodynamic theory of phase separation developed by

Temperature Effects During Capillary Rheometry Testing

May 1, 2002
Author(s)
Anthony J. Bur, S C. Roth, H Lobo
A non-contact temperature monitoring technique based on fluorescence spectroscopy was used to measure the temperature of a polymer resin during capillary rheometry testing. Polyethylene and polycarbonate doped with a fluorescent dye, perylene, were used in
Displaying 1651 - 1675 of 1882