Effects of Aging on Polymerization Kinetics

1990 ◽  
Vol 215 ◽  
Author(s):  
Christopher N. Bowman ◽  
Nikolaos A. Peppas
Keyword(s):  
Relaxation Time ◽  
Theoretical Model ◽  
Light Intensity ◽  
Physical Aging ◽  
Volume Relaxation ◽  
Radical Concentration ◽  
Model Predictions ◽  
Maximum Conversion ◽  
Effects Of Aging ◽  
Crosslinking Reactions

AbstractA theoretical model was developed to describe the physical aging during photopolymerizations and crosslinking reactions of diacrylates and dimethacrylates. The model incorporates the strong coupling between the volume relaxation and the kinetics observed in these reactions. Model predictions are presented for the reaction kinetics, volume relaxation, radical concentration and maximum conversion as a function of light intensity and relaxation time of the polymer.

Theoretical model of the single spin-echo relaxation time for spherical magnetic perturbers

2014 ◽  
Vol 71 (5) ◽  
pp. 1888-1895 ◽  
Author(s):  
Felix T. Kurz ◽  
Thomas Kampf ◽  
Sabine Heiland ◽  
Martin Bendszus ◽  
Heinz-Peter Schlemmer ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Theoretical Model ◽  
Spin Echo ◽  
Single Spin

Hydraulic Driven Rotating Flexible Beam: Theoretical Modal Analysis and Proportional Servo Drive Parameter Influence

2003 ◽  
Author(s):  
Javier Freire ◽  
Esteve Codina ◽  
Munir Khamashta
Keyword(s):  
Theoretical Model ◽  
Modal Analysis ◽  
Dynamic Performance ◽  
Normal Modes ◽  
Flexible Beam ◽  
Servo Drive ◽  
Analysis Methodology ◽  
Model Predictions ◽  
Hydraulic Servo ◽  
Machine Elements

Understanding the behavior of system with flexible elements is increasingly important in modern day technology. Reducing the mass of machine elements leads to a remarkable improvement in dynamic performance. However, a loss of precision also occurs with such an increase in flexibility. In order to arrive at a better understanding of systems with flexible elements, we are investigating the particular behavior of a hydraulic servo driven rotating flexible beam with the aim of obtaining a methodology that could be applied to a real application. To investigate this behavior, a set of models has been developed. In this paper, a theoretical model, using classical modal analysis methodology, is presented. The flexible beam is modeled in a standard way and the hydraulic servo drive is modeled as a boundary condition. Only normal modes will be investigated. This approach allows considering the servo proportional constant and the cylinder mass. It will be show that the servo proportional constant has low influence in the system eigen frequencies. The theoretical model predictions are validated experimentally.

Firefighter Safety Zones: A Theoretical Model Based on Radiative Heating

1998 ◽  
Vol 8 (2) ◽  
pp. 73 ◽  
Author(s):  
BW Butler ◽  
JD Cohen
Keyword(s):  
Theoretical Model ◽  
Radiant Energy ◽  
General Rule ◽  
Quantitative Information ◽  
Radiative Heating ◽  
Flame Height ◽  
Safety Zone ◽  
Model Predictions ◽  
Zone Radius ◽  
Height Model

Quantitative information regarding safety zone size for wildland firefighters is limited. We present a 3-surface theoretical model that describes the net radiant energy transfer to a firefighter standing a specified distance from a fire of specified height. Model predictions compare favorably with qualitative data from entrapments on four wildfires and two previously published models. Calculations indicate that for most fires, safety zones must be greater than 20 m wide to ensure firefighter survival. A general rule-of-thumb derived from this work is that a safety zone radius must be equal to or greater than 4 times the maximum flame height.

HIGH-ORDER DIFFRACTION IN PHOTOREFRACTIVE SBN:Ce DUE TO NON-SINUSOIDAL GRATINGS FORMED BY BEAMS OF COMPARABLE INTENSITY

1993 ◽  
Vol 02 (02) ◽  
pp. 221-227
Author(s):  
HONG-JUN ZHANG ◽  
ZE-SUN TANG ◽  
THOMAS R. MOORE ◽  
ROBERT W. BOYD
Keyword(s):  
Theoretical Model ◽  
Light Intensity ◽  
Intensity Distribution ◽  
High Order ◽  
Light Intensity Distribution ◽  
Order Diffraction ◽  
Beam Coupling ◽  
Sinusoidal Gratings ◽  
Comparable Intensity ◽  
Good Agreement

We have observed multiple-order diffraction from photorefractive gratings formed by two input beams of comparable intensity that interfere in a single crystal of SBN:Ce. High-order diffraction occurs both in the direction of two-beam coupling gain and in the opposite direction. These results are in good agreement with the predictions of a theoretical model that interprets high-order diffraction as a form of Raman-Nath scattering from a highly anharmonic diffraction grating that is formed by a light intensity distribution having a large depth of modulation.

BEHAVIOR IN ELECTRIC FIELDS OF SIMPLE BIOLOGICAL MEMBRANES

2001 ◽  
Vol 15 (09n10) ◽  
pp. 299-308
Author(s):  
MARIA HONCIUC ◽  
ELENA SLAVNICU
Keyword(s):  
Fatty Acids ◽  
Relaxation Time ◽  
Fatty Acid ◽  
Liquid Crystals ◽  
Theoretical Model ◽  
Electric Fields ◽  
Biological Membranes ◽  
Biological Processes ◽  
Electric Permittivity ◽  
Order Of Magnitude

The latest studies in biophysics and biochemistry have revealed the major role that liquid crystals (LC) and related phenomena play in biological processes. To account for a number of membrane mechanisms in view of the theoretical model developed by S. J. Singer, studies were carried out on mixtures of fatty acids (arachidic, lauric, butyric) and cholesterol in different weight percentages. Such mixtures may help one understand some mechanisms on which the operation of biological membranes relies. To this end, the way these mixtures behave in an electric field was studied. Electric measurements were conducted from which the average time of electric relaxation (τ) and average electric permittivity (ε r ) were determined. Depending on cholesterol percentage, changes by more than one order of magnitude were found to occur in the electric relaxation time. The ratio between the various fatty acid components did not influence the average time τ in any significant manner. By contrast, the relative electric permittivity ε r was seen to decrease by at least one order of magnitude with raising the cholesterol percentage. The electric properties of such systems essentially depend on changing the amount of cholesterol in the system.

CW and temporal theoretical model predictions and experimental results for Tm:YAG and Ho:YAG lasers

2008 ◽  
Author(s):  
Eric K. Gorton ◽  
John G. Betterton ◽  
David A. Orchard ◽  
Brian J. Perrett ◽  
Paul D. Mason ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Experimental Results ◽  
Model Predictions

scholarly journals Coupling Reduces Noise: Applying Dynamical Coupling to Reduce Local White Additive Noise

2015 ◽  
Vol 25 (03) ◽  
pp. 1550040 ◽  
Author(s):  
Behnam Kia ◽  
Sarvenaz Kia ◽  
John F. Lindner ◽  
Sudeshna Sinha ◽  
William L. Ditto
Keyword(s):  
Theoretical Model ◽  
Dynamical Systems ◽  
Noise Level ◽  
Additive Noise ◽  
Nonlinear Dynamical Systems ◽  
Coupled Map Lattices ◽  
Nonlinear Dynamical ◽  
Model Predictions ◽  
Dynamical Coupling ◽  
Averaging Filter

We demonstrate how coupling nonlinear dynamical systems can reduce the effects of noise. For simplicity we investigate noisy coupled map lattices and assume noise is white and additive. Noise from different lattice nodes can diffuse across the lattice and lower the noise level of individual nodes. We develop a theoretical model that explains this observed noise evolution and show how the coupled dynamics can naturally function as an averaging filter. Our numerical simulations are in excellent agreement with the model predictions.

scholarly journals The influence of temperature and photoinitiator concentration on photoinitiated polymerization of diacrylate monomer

2005 ◽  
Vol 3 (4) ◽  
pp. 721-730 ◽  
Author(s):  
Lavinia Macarie ◽  
Gheorghe Ilia
Keyword(s):  
Light Intensity ◽  
Tertiary Amine ◽  
Thermal Polymerization ◽  
Optimal Concentration ◽  
Constant Light ◽  
Influence Of Temperature ◽  
Photoinitiated Polymerization ◽  
Maximum Conversion ◽  
Triethyl Amine ◽  
Higher Temperature

AbstractThe behavior of p-methoxybenzoyldiphenylphosphine oxide, previously synthesized, as a photoinitiator for the polymerization of diacrylate monomer, in the presence of 3% (w/w) tertiary amine (triethyl amine) as synergist additive, was studied. The influence of temperature in the range 30–90°C at 3% (w/w) photoinitiator concentration and the influence of the photoinitiator concentration in the range 0.5–3.5% (w/w) at 30°C was investigated by differential scanning photocalorimetry (photo-DSC). In all experiments the photopolymerization was performed at constant light intensity (3 mW cm−2). The maximum conversion was obtained at temperature of 90°C at 3% (w/w) photoinitiator concentration and 3% (w/w) triethyl amine. The optimal concentration of photoinitiator to obtain maximum conversion was 3% (w/w), at 30°C. No thermal polymerization occurred at higher temperature.

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