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Materials

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Displaying 2051 - 2075 of 2366

Degradation and Nanofiller Release of Polymer Nanocomposites Exposed to UV

July 15, 2009
Author(s)
Tinh Nguyen, Bastien T. Pellegrin, Alexander J. Shapiro, Xiaohong Gu, Joannie W. Chin
Nanofillers are increasingly used to enhance multifunctional properties of polymers. However, recent research suggests that nanomaterials may have a negative impact on the environmental health and safety. Since polymers are susceptible to photodegradation

Long-Term Performance of Nano-Filled Polymeric Materials: Effect of ZnO Nanoparticles on Photodegradation of a Waterborne Polyurethane Coating

July 8, 2009
Author(s)
Xiaohong Gu, Dongmei Zhe, Minhua Zhao, Guodong Chen, Nhieu Ly, Paul E. Stutzman, Li Piin Sung, Tinh Nguyen, Joannie W. Chin
Polymers are widely used as exterior coatings in buildings, bridges, aircrafts and automobiles for both protection and aesthetic purposes. However, the service life of the applied coatings is limited due to the photodegradation of polymers induced by

Comprehensive Evaluation of AIMS Texture, Angularity, and Dimension Measurements

July 3, 2009
Author(s)
Enad M. Mahmoud, Leslie L. Gates, Eyad A. Masad, Sinan T. Erdogan, Edward Garboczi
Aggregates are the most widely used construction materials in the world in structures built from both asphaltic and portland cement concrete composites. The performance of these composites is affected by aggregate shape characteristics (e.g., angularity

Microscale Polymer-Nanotube Composites

July 2, 2009
Author(s)
Erik K. Hobbie, Jeffrey A. Fagan, Jan Obrzut, Steven D. Hudson
Microscopic polymer colloids with an interfacial coating of purified single-wall carbon nanotubes (SWCNTs) have been synthesized from length and type sorted SWCNTs. Aqueous SWNCT suspensions sorted through density-gradient ultracentrifugation are used to

Inter-Laboratory Comparisons of NbTi Critical Current Measurements

June 22, 2009
Author(s)
Arno Godeke, D. Turrioni, T. Boutboul, Najib Cheggour, A. K. Ghosh, Loren F. Goodrich, M Meinesz, A. den Ouden
We report on a multi-institute comparison of critical current data, measured on a modern Large Hadron Collider (LHC) NbTi wire that has shown a standard deviation below 1% in critical current density spread in more than 1500 measurements. Inter-laboratory

Internal tin Nb3Sn conductors engineered for fusion and particle accelerator applications

June 22, 2009
Author(s)
Jeffrey Parrell, Y. Zhang, Michael Field, M Meinesz, Yonghua Huang, H Miao, Seungok Hong, Najib Cheggour, Loren F. Goodrich
The critical current density (Jc) of Nb3Sn strand has been significantly improved over the last several years. For most magnet applications, high Jc internal tin has displaced bronze process strand. The highest Jc values are obtained from distributed

Test Results of the First US ITER TF Conductor in SULTAN

June 22, 2009
Author(s)
Nicolai N. Martovetsky, Daniel R. Hatfield, John R. Miller, Chen-yu Gung, Joel S. Schultz, Najib Cheggour, Loren F. Goodrich, Pierluigi Bruzzone, Boris Stepanov, Rainer Wesche, Bernd Seeber
The US Domestic Agency is one of six parties supplying TF cable-in-conduit conductors (CICCs) for ITER. Previous tests have shown that measured performance of the TF CICCs can be much lower than expected from the strand properties at the projected uniaxial

Determination of the Electron Escape Depth for NEXAFS Spectroscopy

June 2, 2009
Author(s)
Daniel A. Fischer, K E. Sohn, M D. Dimitriou, Jan Genzer, C Hawker, E. J. Kramer
Depth profiling using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to determine the carbon atom density as a function of depth by analyzing the post-edge signal in NEXAFS spectra. We show that the common assumption in the

High Strain Rate Tissue Simulant Measurements Using digital Image Correlation

June 1, 2009
Author(s)
Steven P. Mates, Richard L. Rhorer, Richard Everett, Kirth Simmonds, Amit Bagchi
Measuring the response of soft materials to high strain rate deformation is extremely challenging because of the difficulty of achieving dynamic equilibrium during high strain rate mechanical testing such as Kolsky bar testing. Digital image correlation

Carbon Nanomaterials Standards Efforts at NIST

May 24, 2009
Author(s)
Jeffrey A. Fagan
Development of carbon nano-materials for applications has been hindered to date by a lack of standard protocols, i.e. documentary standards, and physical standards such as reference materials, which enable the common inter-comparison between laboratories

Capillary Instability in Nanoimprinted Polymer Films

May 21, 2009
Author(s)
Kyle J. Alvine, Yifu Ding, Hyun Wook Ro, Brian C. Okerberg, Alamgir Karim, Christopher L. Soles, Jack F. Douglas
Capillary forces play an active role in defining the equilibrium structure of nanoscale structures. This effect can be especially pronounced in soft materials such as polymers near or above their glass transition temperatures where material flow is

The Origin of Critical Relative Humidity in Adhesion

May 11, 2009
Author(s)
Christopher C. White, Kar T. Tan, Bryan D. Vogt, Donald L. Hunston
Water is ubiquitous in the atmosphere. Unfortunately, adhesive bonding is susceptible to the environmental attack of water leading to significant depreciation in joint strength and subsequently to premature failures [1-6]. This susceptibility of bonding to

Demonstration of Impedance Matching Using a mu-Negative (MNG) Metamaterial

April 14, 2009
Author(s)
Christopher L. Holloway, R. B. Greegor, C. G. Parazzoli, J. A. Nielsen, M. H. Tanielian, D Vier, S Schultz, Richard Ziolkowski
A mu-negative (MNG) metamaterial hemisphere was used to demonstrate impedance matching for a magnetic loop. The metamaterial was comprised of copper spirals deposited on an alumina substrate. The spirals, hemisphere, and magnetic loop were designed to

Modelling of Thermodynamics and Diffusion in Multicomponent Systems

April 1, 2009
Author(s)
Ursula R. Kattner, Carelyn E. Campbell
The availability of reliable materials data is key to the successful design of materials and manufacturing processes. Commercial alloys rarely consist of only two or three elements, but rather may contain a large number of elements for which the needed

Hydrogen-Steel Compatibility Research at NIST-Boulder

March 30, 2009
Author(s)
Thomas A. Siewert
The NIST Materials Reliability Division is outfitting a high pressure (100 MPa) hydrogen testing facility to collect mechanical and thermodynamic property data on various candidate structural materials, and is developing data on nondestructive sensors that

Dielectric Spectroscopy Investigation of Relaxation in C60-Polyisoprene Nanocomposites

March 23, 2009
Author(s)
Yifu Ding, Sebastian Pawlus, Alexei Sokolov, Jack F. Douglas, Alamgir Karim, Christopher Soles
We investigate the influence of adding C60 nanoparticles on the dielectric relaxation spectra of both unentangled and entangled polyisoprene (PIP). Relaxation modes corresponding to both segmental and chain relaxation were analyzed over a broad temperature

Examination of thin film modulus for a series of poly(alkyl methacrylates)

March 22, 2009
Author(s)
Jessica M. Torres, Christopher Stafford, Bryan D. Vogt
In this work, the modulus of polymer thin films for a homologous series of poly(n-alkyl methacrylate)s will be discussed. In particular, the impact of the degree of undercooling from bulk Tg on the deviations will be explored as Tg is significantly

Quantifying Residual Stress in Nanoscale Thin Polymer Films via Surface Wrinkling

March 19, 2009
Author(s)
Jun Y. Chung, Thomas Q. Chastek, Michael J. Fasolka, Hyun W. Ro, Christopher Stafford
Residual stress, a pervasive consequence of solid materials processing, is stress that remains in a material after external forces have been removed. In polymeric materials, residual stress results from processes, such as film formation, that force and
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