Negative activation energies and curved Arrhenius plots. 1. Theory of reactions over potential wells

1984 ◽  
Vol 88 (25) ◽  
pp. 6429-6435 ◽  
Author(s):  
Michael Mozurkewich ◽  
Sidney W. Benson
Keyword(s):  
Activation Energies ◽  
Potential Wells ◽  
Arrhenius Plots

scholarly journals Thermo-oxidative stability of waterborne polyurethanes with catalysts of different selectivity evaluated by non-isothermal thermogravimetry

2007 ◽  
Vol 72 (7) ◽  
pp. 723-735 ◽  
Author(s):  
Suzana Cakic ◽  
Goran Nikolic ◽  
Jakov Stamenkovic
Keyword(s):  
Thermal Stability ◽  
Oxidative Stability ◽  
Temperature Interval ◽  
Activation Energies ◽  
Kinetics Parameters ◽  
Arrhenius Plots ◽  
Isothermal Thermogravimetry ◽  
Degradation Processes ◽  
Waterborne Polyurethanes ◽  
Degree Of Degradation

Thermogravimetry was used for the evaluation of the thermo-oxidative stability of waterborne polyurethanes (wbPUR) containing catalysts of different selectivity. From Arrhenius plots, activation energies of between 50 and 120 kJ mol-1 for wbPUR were determined, depending on the temperature interval, selectivity of the catalyst and degree of degradation. Waterborne polyurethanes without catalyst showed lower thermal stability than waterborne polyurethanes with catalysts of different selectivity. Non-isothermal thermogravimetry indicated the presence of different degradation processes and enabled the kinetics parameters at higher degrees of degradation to be evaluated. .

Negative activation energies and curved Arrhenius plots. 2. Hydroxyl + carbon monoxide

1984 ◽  
Vol 88 (25) ◽  
pp. 6435-6441 ◽  
Author(s):  
Michael Mozurkewich ◽  
John J. Lamb ◽  
Sidney W. Benson
Keyword(s):  
Carbon Monoxide ◽  
Activation Energies ◽  
Arrhenius Plots

scholarly journals Role of ZnO in Dc Electrical Conductivity of Lithium Bismuthate Glasses

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Shashidhar Bale ◽  
Syed Rahman
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Quaternary System ◽  
Activation Energies ◽  
Lithium Ions ◽  
Arrhenius Plots ◽  
Dc Electrical Conductivity ◽  
Straight Line

Glasses of various compositions belonging to the Bi2O3-B2O3-ZnO-Li2O quaternary system were prepared using melt quench technique. Dc electric measurements were done on the samples, and activation energies are determined. Arrhenius plots showed straight line behaviour. It is observed that the conductivity of the samples increased with temperature and also with Li2O content, whereas the activation energy decreased with Li2O content. The isothermal plots for constant ZnO and constant Bi2O3 glasses revealed that the conduction in these glasses is due to lithium ions only. The isothermal plots for constant lithium containing glasses varied nonlinearly with two maxima, which is attributed to mixed former effect. The variation is explained based on Anderson-Stuart model.

scholarly journals Ignition Activation Energy of Materials based on Polyamide 6

2016 ◽  
Vol 11 (1) ◽  
pp. 27-31
Author(s):  
Peter Rantuch ◽  
Igor Wachter ◽  
Ivan Hrušovský ◽  
Karol Balog
Keyword(s):  
Activation Energy ◽  
Polyamide 6 ◽  
Activation Energies ◽  
Arrhenius Plots ◽  
Flame Combustion ◽  
Time To Initiation ◽  
Different Temperatures

Abstract This contribution is aimed to compare the values of the ignition activation energies of two types of polyamide – Slovamid 6 FRB and Slovamid GF 50 LTS. Samples were isothermally stressed at five different temperatures between 500 °C a 550 °C, while the time to initiation of the flame combustion was monitored. Subsequently from the measured times were compiled Arrhenius plots under which activation energy of ignition of both polymers were calculated. The values of activation energies were 106 kJ.mol−1 and 158.0 kJ.mol−1 for Slovamid 6 FRB 4 and Slovamid 6 GF 50 LTS.

scholarly journals The temperature-dependence of the loss of latency of lysosomal enzymes

1978 ◽  
Vol 172 (1) ◽  
pp. 163-173 ◽  
Author(s):  
Robin C. Ruth ◽  
William B. Weglicki
Keyword(s):  
Elevated Temperature ◽  
Phase Change ◽  
Temperature Dependence ◽  
Rat Liver ◽  
Lysosomal Enzymes ◽  
Activation Energies ◽  
Slow Phase ◽  
Rapid Phase ◽  
Arrhenius Plots ◽  
Biphasic Kinetics

1. When Triton-filled lysosomes from rat liver are incubated for up to 50min at 37°C, pH7.4, in 0.25m-sucrose, no loss of latency of N-acetyl-β-glucosaminidase or p-nitrophenyl phosphatase occurs unless the incubated lysosomes are cooled to approx. 15°C. 2. It is suggested that a phase change takes place in the incubated lysosomal membranes on cooling; it starts at approx. 15°C and probably is not complete at 0°C. 3. Incubation of the lysosomes causes an increased potential for loss of latency of the lysosomal enzymes. This potential is not fully expressed at elevated temperature (e.g. 37°C), but is expressed on cooling. 4. The increase at elevated temperature in potential for loss of latency exhibits biphasic kinetics, with an initial rapid phase followed by a slower phase, which is linear with respect to time. The extra loss of latency resulting from the rapid phase in proportional to the temperature of the incubation. 5. Arrhenius plots of the increase is potential for loss of latency during the slow phase for N-acetyl-β-glucosaminidase and p-nitrophenyl phosphatase exhibit marked deviations from linearity beginning at approx. 15°C. This suggests that the increase in potential for loss of latency is affected by a phase change that occurs around this temperature. 6. Activation energies for the increase in potential for loss of latency at and above 22°C are 53.1±5.4kJ/mol (12.7±1.3kcal/mol) for N-acetyl-β-glucosaminidase and 45.2±7.5kJ/mol (10.8±1.8kcal/mol) for p-nitrophenyl phosphatase. It is postulated that these energies reflect enzymic action, the products of which cause loss of latency to occur on cooling.

Deep level study in epitaxial 4H-SiC grown on substrates inclined toward

2002 ◽  
Vol 719 ◽  
Author(s):  
Masashi Kato ◽  
Masaya Ichimura ◽  
Eisuke Arai ◽  
Shigehiro Nishino
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Activation Energies ◽  
Thickness Dependence ◽  
Epitaxial Layers ◽  
Transient Spectroscopy

AbstractEpitaxial layers of 4H-SiC are grown on (0001) substrates inclined toward <1120> and <1100> directions. Defects in these films are characterized by deep level transient spectroscopy (DLTS) in order to clarify the dependence of concentrations and activation energies on substrate inclination. DLTS results show no such dependence on substrate inclination but show thickness dependence of the concentration.

Activation energies of technological termodonors in neutron doped silicon

2015 ◽  
Vol 19 (1/2) ◽  
Author(s):  
L. I. Panasjuk ◽  
V. V. Kolomoets ◽  
V. N. Ermakov ◽  
S. A. Fedosov ◽  
L. V. Yashchynskiy
Keyword(s):  
Activation Energies ◽  
Doped Silicon
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