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105 results on '"Kranbuehl, David E."'

6. Photooxidation of amino acids and proteins mediated by novel 1,8-naphthalimide derivatives

Author

Abraham, Bindu, Kelly, Lisa A., Kranbuehl, David E., Bagdassarian, Carey K., and May, Sylvio

Subjects
Chemistry, Physical and theoretical -- Research, Oxidation-reduction reaction -- Research, Amino acids -- Research, Amino acids -- Chemical properties, Amino acids -- Structure, Chemicals, plastics and rubber industries
Abstract

The ground- and excited-state interactions of N-(2-ethanoic acid)-1,8-naphthalimide (NI-ala), along with tryptophan and tyrosine-substituted 1,8-naphthalimide derivatives (NI-trp and NI-tyr), with amino acids and native proteins are investigated in aqueous buffered solution. Results suggest that the studies have identified the potential oxidative targets in native proteins and demonstrate the utility of naphthalimide derivatives to photomodify native proteins.

Published
2003

7. Evolution of rate-promoting oscillations in a model enzyme

Author

Williams, G.S. Blair, Hossain, Aftab M., Kranbuehl, David E., Bagdassarian, Carey K., and May, Sylvio

Subjects
Molecular dynamics -- Research, Enzymes -- Research, Enzymes -- Chemical properties, Oscillation -- Research, Chemicals, plastics and rubber industries
Abstract

The evolutionary scheme coupled to approximate normal-mode analysis to explore the means by which catalytic fitness is increased is presented. Results reveal that the number and distribution of loose, intermediate, and stiff domains in the body of an enzyme molecule can govern fluctuation patterns leading to increased catalytic fitness.

Published
2003

11. In-situ Frequency Dependent Dielectric Sensing of Cure

Author

Kranbuehl, David E

Subjects
Nonmetallic Materials
Abstract

With the expanding use of polymeric materials as composite matrices, adhesives, coatings and films, the need to develop low cost, automated fabrication processes to produce consistently high quality parts is critical. Essential to the development of reliable, automated, intelligent processing is the ability to continuously monitor the changing state of the polymeric resin in-situ in the fabrication tool. This final report discusses work done on developing dielectric sensing to monitor polymeric material cure and which provides a fundamental understanding of the underlying science for the use of frequency dependent dielectri sensors to monitor the cure process.

Published
1996

12. Graphene Oxide’s Reduction of Hydrolytic Degradation in Polyamide-11

Author

Hocker, Samuel JA, Hudson-Smit, Natalie, Smith, Patrick, Komatsu, Chris, Dickinson, Laura R., Schniepp, Hannes C., and Kranbuehl, David E.

Subjects
Article
Abstract

Graphene oxide (GO) was incorporated into polyamide-11 (PA11) via in-situ polymerization. The GO-PA11 nano-composite had elevated resistance to hydrolytic degradation. At a loading of 1 mg/g, GO to PA11, the accelerated aging equilibrium molecular weight of GO-PA11 was higher (33 and 34 kDa at 100 and 120 °C, respectively) compared to neat PA11 (23 and 24 kDa at 100 and 120 °C, respectively). Neat PA11 had hydrolysis rate constants (k(H)) of 2.8 and 12 (×10(−2) day(−1)) when aged at 100 and 120 °C, respectively, and re-polymerization rate constants (k(P)) of 5.0 and 23 (×10(−5) day(−1)), respectively. The higher equilibrium molecular weight for GO-PA11 loaded at 1 mg/g was the result of a decreased k(H), 1.8 and 4.5 (×10(−2) day(−1)), and an increased k(P), 10 and 17 (×10(−5) day(−1)) compared with neat PA11 at 100 and 120 °C, respectively. The decreased rate of degradation and resulting 40 % increased equilibrium molecular weight of GO-PA11 was attributed to the highly asymmetric planar GO nano-sheets that inhibited the molecular mobility of water and the polymer chain. The crystallinity of the polymer matrix was similarly affected by a reduction in chain mobility during annealing due to the GO nanoparticles’ chemistry and highly asymmetric nano-planar sheet structure.

Published
2017

13. Textile composite processing science

Author

Loos, Alfred C, Hammond, Vincent H, Kranbuehl, David E, and Hasko, Gregory H

Subjects
Composite Materials
Abstract

A multi-dimensional model of the Resin Transfer Molding (RTM) process was developed for the prediction of the infiltration behavior of a resin into an anisotropic fiber preform. Frequency dependent electromagnetic sensing (FDEMS) was developed for in-situ monitoring of the RTM process. Flow visualization and mold filling experiments were conducted to verify sensor measurements and model predictions. Test results indicated good agreement between model predictions, sensor readings, and experimental data.

Published
1993

14. FDEMS Sensing for Automated Intelligent Processing of PMR-15

Author

Kranbuehl, David E, Hood, D. K, Rogozinski, J, Barksdale, R, Loos, Alfred C, and McRae, Doug

Subjects
Nonmetallic Materials
Abstract

The purpose of this grant was to develop frequency dependent dielectric measurements, often called FDEMS (frequency dependent electromagnetic sensing), to monitor and intelligently control the cure process in PMR-15, a stoichiometric mixture of a nadic ester, dimethyl ester, and methylendianiline in a monomor ratio.

Published
1993

15. Analytical modeling and sensor monitoring for optimal processing of advanced textile structural composites by resin transfer molding

Author

Loos, Alfred C, Macrae, John D, Hammond, Vincent H, Kranbuehl, David E, Hart, Sean M, Hasko, Gregory H, and Markus, Alan M

Subjects
Composite Materials
Abstract

A two-dimensional model of the resin transfer molding (RTM) process was developed which can be used to simulate the infiltration of resin into an anisotropic fibrous preform. Frequency dependent electromagnetic sensing (FDEMS) has been developed for in situ monitoring of the RTM process. Flow visualization tests were performed to obtain data which can be used to verify the sensor measurements and the model predictions. Results of the tests showed that FDEMS can accurately detect the position of the resin flow-front during mold filling, and that the model predicted flow-front patterns agreed well with the measured flow-front patterns.

Published
1993

16. Monitoring Polymer Curing Via Electromagnetic Impedance

Author

Freeman, William T, Covington, John C, Kranbuehl, David E, Hoff, Melanie, and Delos, Susan

Subjects
Physical Sciences
Abstract

New nondestructive in-situ electromagnetic-impedance measurement technique senses cure-processing properties of high-temperature, high-performance thermostat and thermoplastic resins. Continuous frequency-dependent measurement and analysis performed during curing cycle. Monitors and measures molecular properties of polymeric resin in liquid and solid states. Applications include nondestructive means for evaluation of materials, determination of "window" boundaries of curing cycles of thermoplastics and thermoset resins, and for online, closed-loop control of curing cycles.

Published
1992

17. Infiltration/cure modeling of resin transfer molded composite materials using advanced fiber architectures

Author

Loos, Alfred C, Weideman, Mark H, Long, Edward R., Jr, Kranbuehl, David E, Kinsley, Philip J, and Hart, Sean M

Subjects
Composite Materials
Abstract

A model was developed which can be used to simulate infiltration and cure of textile composites by resin transfer molding. Fabric preforms were resin infiltrated and cured using model generated optimized one-step infiltration/cure protocols. Frequency dependent electromagnetic sensing (FDEMS) was used to monitor in situ resin infiltration and cure during processing. FDEMS measurements of infiltration time, resin viscosity, and resin degree of cure agreed well with values predicted by the simulation model. Textile composites fabricated using a one-step infiltration/cure procedure were uniformly resin impregnated and void free. Fiber volume fraction measurements by the resin digestion method compared well with values predicted using the model.

Published
1991

18. Analytical modeling and sensor monitoring for optimal processing of polymeric composite material systems

Author

Loos, Alfred C, Weideman, Mark H, Kranbuehl, David E, and Long, Edward R., Jr

Subjects
Composite Materials
Abstract

Process simulation models and cure monitoring sensors are discussed for use in optimal processing of fiber-reinforced composites. Analytical models relate the specified temperature and pressure cure cycle to the thermal, chemical, and physical processes occurring in the composite during consolidation and cure. Frequency-dependent electromagnetic sensing (FDEMS) is described as an in situ sensor for monitoring the composite curing process and for verification of process simulation models. A model for resin transfer molding of textile composites is used to illustrate the predictive capabilities of a process simulation model. The model is used to calculate the resin infiltration time, fiber volume fraction, resin viscosity, and resin degree of cure. Results of the model are compared with in situ FDEMS measurements.

Published
1991

20. Separating connectivity and expansion effects in polymer single chain dynamics.

Author

Kranbuehl, David E. and Verdier, Peter H.

Subjects
*POLYMERS, *LATTICE dynamics, *COMPUTER simulation
Abstract

Studies the effects of chain volume and connectivity upon the motions of flexible polymers in dilute solution using computer simulation of simple off-lattice bead-flip models. Long internal relaxation times given for free-draining chains with bead diameters from 0-0.93 times the stick lengths; Chain-length dependence of relaxation times and translational diffusion.

Published
1997
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27. In-Situ Formation of Silver Nanoparticles in PEI

Author

Cotts, S.K., Compton, J., Kranbuehl, David E., Boiteux, Gisèle, Department of Chemistry and Applied Science, College of William and Mary [Williamsburg] (WM), Ingénierie des Matériaux Polymères - Laboratoire des Matériaux Polymères et des Biomatériaux (IMP-LMPB), Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Institut de Chimie du CNRS (INC)

Published
2009

32. Dielectric probe; method and apparatus including its use

Author

Kranbuehl, David E

Subjects
Electronics And Electrical Engineering
Abstract

A dielectric probe for use with conventional frequency and time domain impedance analyzers comprises two chemically resistant electrodes deposited in an interdigitated pectinate configuration on particular non-conductive substrates, the spaces between the digits thereof being no greater than about 0.01 inch; methods and apparatus for monitoring and/or controlling chemical reactions, particularly polymerization reactions, in contact therewith, wherein the complex permittivity may be calculated over a wide range of frequencies and temperatures.

Published
1988

33. Method of using a dielectric probe to monitor the characteristics of a medium

Author

Kranbuehl, David E

Subjects
Electronics And Electrical Engineering
Abstract

A dielectric probe for use with conventional frequency and time domain impedance analyzers comprises two chemically resistant electrodes deposited in an interdigitated pectinate configuration on particular non-conductive substrates, the spaces between the digits thereof being no greater than about 0.01 inch; methods and apparatus for monitoring and/or controlling chemical reactions, particularly polymerization reactions, in contact therewith, wherein the complex permittivity may be calculated over a wide range of frequencies and temperatures.

Published
1987

41. Synthesis and reactive features of a terpolymer: Poly( N-vinyl-2-pyrrolidone- co-vinyl acetate- co-glycidyl methacrylate).

Author

Hood, David K., Kranbuehl, David E., Glover, A. Jaeton, SENak, LaurENce, Zhu, Chao, Ozkan, Seher, and Musa, Osama M.

Subjects
POLYMERIZATION, REACTIVITY (Chemistry), PYRROLIDINONES, VINYL acetate, GLYCIDYL methacrylate, CROSSLINKED polymers, COATING processes
Abstract

A polyvinyl pyrrolidone terpolymer system is described that can be chemically cross-linked at moderate, 70-100°C, temperatures. The system has significant potential for development of durable long-lasting pyrrolidone coatings in a wide range of applications, particularly in water filtration membrane construction where leaching is an unresolved, serious problem. The synthesis of the terpolymer, poly( N-vinyl-2-pyrrolidone- co-vinyl acetate- co-glycidyl methacrylate), by free radical polymerization is described. The reactive features of this terpolymer are presented in the context of acidic anhydride curing. In a polar aprotic solvent, the terpolymer is reacted with poly(methyl vinyl ether- co-maleic acid) and cured thermally. Key aspects of the terpolymer synthesis and the acid anhydride cross-linking reaction using DSC, rheology, FTIR, and a small molecule model system to study the cross-linking chemistry are presented. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Published
2013
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