Activation energy and critical concentration of peroxy radicals in low-temperature oxidation of natural rubber and 1,4 cis-polyisoprene

2007 ◽  
Vol 57 (1) ◽  
pp. 121-127 ◽  
Author(s):  
A. Tkáč
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Natural Rubber ◽  
Critical Concentration ◽  
Peroxy Radicals ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation

Kinetics of MoSi2 pest during low-temperature oxidation

1993 ◽  
Vol 8 (7) ◽  
pp. 1605-1610 ◽  
Author(s):  
T.C. Chou ◽  
T.G. Nieh
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Growth Kinetics ◽  
Growth Stage ◽  
Sample Volume ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Oxidation In Air ◽  
Two Stages ◽  
Kinetics Of

The kinetics of MoSi2 pest, caused by oxidation in air, has been studied. Experimental results indicated that pest disintegration occurred at temperatures between 375 and 500 °C. The volumes of test samples increased with oxidation duration. Analysis of change in sample volume versus oxidation duration revealed that the pest disintegration consisted of two stages, namely nucleation (or incubation) and growth. The onset of the growth stage depended on the test temperature. More importantly, changes in sample volume were found to obey a linear relationship with time during the growth stage. Equations were formulated to demonstrate that the growth kinetics of pest disintegration was proportional to the rates of change in sample volume. The rates of volume change during MoSi2 pest were calculated to be 4.9 × 10−6, 2.8 × 10−5, 3.7 × 10−5, and 5.4 × 10−5 cm3/s at 375, 400, 425, and 450 °C, respectively; the growth kinetics increased with oxidation temperature. The activation energy for the growth stage of pest disintegration was determined to be 27.6 kcal/mole, which agrees well with the activation energy for the low-temperature oxidation of MoSi2.

scholarly journals Influence of Co-Precipitation Agent on the Structure, Texture and Catalytic Activity of Au-CeO2 Catalysts in Low-Temperature Oxidation of Benzyl Alcohol

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 641
Author(s):  
Lukasz Wolski ◽  
Grzegorz Nowaczyk ◽  
Stefan Jurga ◽  
Maria Ziolek
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Low Temperature ◽  
Benzyl Alcohol ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Oxidation Of Benzyl Alcohol ◽  
Key Factor ◽  
Au Particle Size ◽  
Co Precipitation

The aim of the study was to establish the influence of a co-precipitation agent (i.e., NaOH–immediate precipitation; hexamethylenetetramine/urea–gradual precipitation and growth of nanostructures) on the properties and catalytic activity of as-synthesized Au-CeO2 nanocomposites. All catalysts were fully characterized with the use of XRD, nitrogen physisorption, ICP-OES, SEM, HR-TEM, UV-vis, XPS, and tested in low-temperature oxidation of benzyl alcohol as a model oxidation reaction. The results obtained in this study indicated that the type of co-precipitation agent has a significant impact on the growth of gold species. Immediate co-precipitation of Au-CeO2 nanostructures with the use of NaOH allowed obtainment of considerably smaller and more homogeneous in size gold nanoparticles than those formed by gradual co-precipitation and growth of Au-CeO2 nanostructures in the presence of hexamethylenetetramine or urea. In the catalytic tests, it was established that the key factor promoting high activity in low-temperature oxidation of benzyl alcohol was size of gold nanoparticles. The highest conversion of the alcohol was observed for the catalyst containing the smallest Au particle size (i.e., Au-CeO2 nanocomposite prepared with the use of NaOH as a co-precipitation agent).

Low temperature oxidation of copper alloys—AEM and AFM characterization

2007 ◽  
Vol 42 (12) ◽  
pp. 4684-4691 ◽  
Author(s):  
Mari Honkanen ◽  
Minnamari Vippola ◽  
Toivo Lepistö
Keyword(s):  
Low Temperature ◽  
Copper Alloys ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation
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