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Displaying 1151 - 1175 of 1923

Little Things Mean a Lot: Water and the Adhesive Bond

February 21, 2010
Author(s)
Donald L. Hunston, Kar T. Tan, Bryan D. Vogt, Sushil K. Satija, Cyril Clerici, David E. White
The ability of water to dramatically weaken many types of adhesive bonds has been widely studied. One surprising result is the existence of a critical moisture level in the bond. Above this level the strength drops to very low values. Numerous studies have

Roles of Adhesive and Interfacial Properties on Humidity-induced Failure

February 21, 2010
Author(s)
Kar T. Tan, Christopher C. White, Donald L. Hunston, Kristen L. Steffens, Hatlee Timothy, Kristen Hamilton, Vogt D. Bryan
Adhesion loss due to moisture is a fundamental problem in a large diversity of industries ranging from microelectronics and automotive to aerospace. This study investigates the durability of model adhesive joints consisting of a homologous series of poly(n

Challenges in Continuum Modeling of Intergranular Fracture

February 11, 2010
Author(s)
Valerie R. Coffman, James P. Sethna
Intergranular fracture in polycrystals is often simulated by finite elements coupled to a cohesive-zone model for the interfaces, requiring cohesive laws for grain boundaries as a function of their geometry. We discuss three challenges in understanding

Electrically-stimulated gradients in water and counterion concentrations within electroactive polymer actuators

February 1, 2010
Author(s)
Jong Keun Park, Paul J. Jones, Chris Sahagun, Kirt A. Page, Daniel S. Hussey, David L. Jacobson, Sarah E. Morgan, Robert B. Moore
While ionic polymer metal composites (IPMCs) have been studied for more than 10 years, the specific actuation mechanism is still unclear. In this work, neutron imaging, applied potential (AP) and current sensing (CS) atomic force microscopy (AFM) methods

Gradient and Microfluidic Library Approaches to Polymer Interfaces

January 1, 2010
Author(s)
Michael J. Fasolka, Christopher M. Stafford, Kathryn L. Beers
We present and overview of research conducted at the National Institute of Standards and Technology aimed at developing combinatorial and high throughput measurement approaches to polymer surfaces, interfaces and thin films. Topics include, 1) the

IMMOBILIZED ENZYME CATALYZED POLYMERIZATION REACTIONS IN MICROREACTORS

January 1, 2010
Author(s)
Santanu S. Kundu, Atul Bhangale, William E. Wallace, Kathleen M. Flynn, Richard Gross, Kathryn L. Beers
Application of microreactor technologies enable improved safety, selectivity and yield in a range of chemical reactions in addition to new measurement methods that are often faster, cheaper and more accurate than traditional methods. In this study we have

IMPACT OF IMMOBILIZATION SUPPORTS FOR POLYESTERS SYNTHESIS ACTIVITY OF CANDIDA ANTARTICA LIPASE B

January 1, 2010
Author(s)
Atul Bhangale, Santanu S. Kundu, Wenchun Xie, William E. Wallace, Kathleen M. Flynn, Kathryn L. Beers, Richard Gross
Epoxy functionalized supports are known to be suitable for industrial-scale immobilization of enzymes for biocatalysis. However, chemistry across these epoxy groups is known to affect the catalytic performance of the enzymes.In order to achieve a balance

MEMS Parallel Plate Rheometer for Oscillatory Shear Micro Rheology Measurements

December 11, 2009
Author(s)
Gordon Christopher, Nicholas G. Dagalakis, Steven D. Hudson, Kalman D. Migler
Growing numbers of applications including proteomics, cosmetics, and thin film coatings use novel viscoelastic materials that derive their rheological properties from micro scale structure created by the inclusion of long chain molecules, nano particles

Gradient Nanofiber Scaffold Libraries for Rapid Screening of Cell-Material Interactions

December 1, 2009
Author(s)
Carl G. Simon Jr., Murugan Ramalingam, Marian F. Young, Vinoy Thomas
Scaffolds play a key role in tissue engineering wherein they provide structural support for cells to adhere, grow and guide them to synthesize tissue. Scaffolds made of multiple biomaterials are typically required to mimic the three-dimensional (3D)

NIST Reference Material Scaffolds for Tissue Engineering

December 1, 2009
Author(s)
Carl G. Simon Jr.
The National Institute of Standards and Technology (NIST) has deployed Reference Material (RM) scaffolds for tissue engineering: a series of well-characterized 3D tissue scaffolds with differing porosities (RM 8395, RM 8396 and RM 8397) (Fig. 1). Customers

Electrical Conductivity and Relaxation in Poly(3-hexylthiophene)

November 25, 2009
Author(s)
Jan Obrzut, Kirt A. Page
ABSTRACT: We studied the complex conductivity of regio-regular poly(3-hexylthiophene) (P3HT) in the temperature range between 193K to 333 K (-80 C to 60 C) and in the frequency range from the direct current (DC) to 12 GHz. The identified relaxation process

A METHODOLOGY FOR DETECTING RESIDUAL PHOSPHORIC ACID IN POLYBENZOXAZOLE FIBERS

November 24, 2009
Author(s)
Eun S. Park, John R. Sieber, Charles M. Guttman, Kirk D. Rice, Kathleen M. Flynn, Stephanie S. Watson, Gale A. Holmes
There is great interest in the degradation of ballistic fibers from exposure to sunlight and high humidity, because it directly affects the lives of people who use protective ballistic armor. However, to date, no mechanism has been found to explain how

Electrical Characterization of Soluble Anthradithiophene Derivatives

November 19, 2009
Author(s)
Brad Conrad, Calvin Chan, Marsha A. Loth, John E. Anthony, David J. Gundlach
Organic semiconductors remain an active subject for device physics and material science because of their varied electrical properties and potential for low-cost, high-throughput roll-to-roll processing. Several high-mobility oligomers, such as pentacene

Mass transfer in two-phase microchannel flows

November 4, 2009
Author(s)
Jeffrey D. Martin, Steven D. Hudson
Drop-based microfluidic devices are becoming more common and molecular mass transfer and drop circulation are issues that affect the performance of such devices. Moreover, interfacial properties and surfactant mass transfer rates govern emulsion behavior
Displaying 1151 - 1175 of 1923
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