THE KINETICS OF THE THERMAL REACTIONS OF ETHYLENE OXIDE

1963 ◽  
Vol 41 (12) ◽  
pp. 2956-2961 ◽  
Author(s):  
M. Lynne Neufeld ◽  
Arthur T. Blades
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Ethylene Oxide ◽  
Thermal Reactions ◽  
Kinetics Of

The thermal reactions of ethylene oxide in the presence of an excess of propylene have been studied as a function of pressure and it has been found that there are two sets of products, acetaldehyde and free radicals, presumably methyl and formyl. These products are believed to arise from an excited acetaldehyde intermediate. Some evidence has been obtained for the occurrence of a surface-catalyzed rearrangement to acetaldehyde but the free radical products are uninfluenced by surface.

Kinetics of the thermal reactions of ethylene. Part II. Ethylene–ethane mixtures

1968 ◽  
Vol 46 (14) ◽  
pp. 2427-2433 ◽  
Author(s):  
M. L. Boyd ◽  
M. H. Back
Keyword(s):  
Free Radical ◽  
Product Formation ◽  
Radical Chain ◽  
Thermal Reactions ◽  
Temperature Range ◽  
Initiation Step ◽  
Chain Polymerization ◽  
Main Effects ◽  
Kinetics Of ◽  
Simplified Mechanism

Mixtures of ethane and ethylene have been pyrolyzed in the temperature range 563–600 °C and at pressures from 30–60 cm. The products were similar to those obtained from the pyrolysis of ethylene by itself, described m Part I, with a marked increase in the yields of the saturated products. The initial rates of product formation and the dependence of these rates on the concentration of ethane suggest that the initiation step is the same as that proposed in the pyrolysis of ethylene alone, viz.[Formula: see text]and that the reaction[Formula: see text]is not an important source of radicals. A simplified mechanism is outlined to account for the main effects of ethane on the free radical chain polymerization.

ESR studies of free radicals in solution. IV. Kinetics of the cysteinyl free radical generated by ceric ion oxidation

1974 ◽  
Vol 15 (3) ◽  
pp. 427-443 ◽  
Author(s):  
Jean C Kertesz ◽  
Walter Wolf ◽  
Michael B Wolf ◽  
Brian J Sullivan
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Ceric Ion ◽  
Kinetics Of

scholarly journals Competition Kinetics of the Nonbranched-Chain Addition of Free Radicals to Olefins, Formaldehyde, and Oxygen

2011 ◽  
Vol 2011 ◽  
pp. 1-19
Author(s):  
M. M. Silaev
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Binary Systems ◽  
Hydrogen Oxidation ◽  
Rate Equations ◽  
Chain Process ◽  
Kinetic Chain ◽  
Set Up ◽  
Kinetics Of ◽  
Unsaturated Component

Five reaction schemes are suggested for the initiated nonbranched-chain addition of free radicals to the multiple bonds of alkenes, formaldehyde, and oxygen. The schemes include reactions competing with chain propagation through a reactive free radical. The chain evolution stage in these schemes involves three or four types of free radicals. One of them— , , , , or —is relatively low-reactive and inhibits the chain process by shortening of the kinetic chain length. Based on the suggested schemes, nine rate equations containing one to three parameters to be determined directly are set up using quasi-steady-state treatment. These equations provide good fits for the nonmonotonic (peaking) dependences of the formation rates of the molecular addition products (1 : 1 adducts) on the concentration of the unsaturated component in liquid homogeneous binary systems consisting of a saturated component (hydrocarbon, alcohol, etc.) and an unsaturated component (olefin, formaldehyde, or dioxygen). The unsaturated compound in these systems is both a reactant and an autoinhibitor generating low-reactive free radicals. A similar kinetic description is applicable to nonbranched-chain free-radical hydrogen oxidation. The energetics of the key radical-molecule reactions is considered.

Kinetics of the thermal reactions of ethylene. Part I

1968 ◽  
Vol 46 (14) ◽  
pp. 2415-2426 ◽  
Author(s):  
M. L. Boyd ◽  
T-M. Wu ◽  
M. H. Back
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Free Radical ◽  
Induction Period ◽  
Pressure Range ◽  
Kcal Mole ◽  
Radical Chain ◽  
Thermal Reactions ◽  
Chain Polymerization ◽  
Kinetics Of

The pyrolysis of ethylene has been studied in the temperature range 500–600 °C and the pressure range 15–60 cm. The main products were ethane, propylene, butene, butadiene, and a polymer of molecular weight corresponding to C8 or higher. Small amounts of methane, butane, unsaturated C5, unsaturated C6, and benzene were also measured. Of the main products, propylene, butene, and butadiene showed an induction period, as long as several minutes at the lowest temperature. The order with respect to ethylene of ethane, propylene, and butene was close to two and the activation energy of the rates was approximately 40 kcal/mole. The results have been interpreted in terms of a free radical chain polymerization. It is suggested that the polymer formed is unstable and decomposes to yield the products for which an induction period was observed.

Non-isothermal Kinetics of Free Radical Polymerization of 2-Phenylethyl (Meth)acrylate

2018 ◽  
Vol 8 (3) ◽  
pp. 585-594
Author(s):  
Khdbudin Mulani ◽  
Ravindra Ghorpade ◽  
Surendra Ponrathnam ◽  
Nayaku Chavan ◽  
Kamini Donde
Keyword(s):  
Free Radical ◽  
Radical Polymerization ◽  
Free Radical Polymerization ◽  
Isothermal Kinetics ◽  
Kinetics Of

Study of antioxidant potential in leaves, stems, nuts of Juglans regia L.

2012 ◽  
Vol 1 (10) ◽  
pp. 79 ◽  
Author(s):  
G. Raja* ◽  
Ivvala Anand Shaker ◽  
Inampudi Sailaja ◽  
R. Swaminathan ◽  
S. Saleem Basha ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Juglans Regia ◽  
Radical Scavenging ◽  
Antioxidant Compounds ◽  
Free Radical Damage ◽  
Radical Damage

Natural antioxidants can protect the human body from free radicals and retard the progress of many chronic diseases as well as lipid oxidative rancidity in foods. The role of antioxidants has protected effect against free radical damage that may cause many diseases including cancer. Primary sources of naturally occurring antioxidants are known as whole grains, fruits, and vegetables. Several studies suggest that regular consumption of nuts, mostly walnuts, may have beneficial effects against oxidative stress mediated diseases such as cardiovascular disease and cancer. The role of antioxidants has attracted much interest with respect to their protective effect against free radical damage that may cause many diseases including cancer. Juglans regia L. (walnut) contains antioxidant compounds, which are thought to contribute to their biological properties. Polyphenols, flavonoids and flavonols concentrations and antioxidant activity of Leaves, Stems and Nuts extract of Juglans regia L. as evaluated using DPPH, ABTS, Nitric acid, hydroxyl and superoxide radical scavenging activity, lipid peroxidation and total oxidation activity were determined. The antioxidant activities of Leaves, Stems and Nuts extract of Juglans regia L. were concentration dependent in different experimental models and it was observed that free radicals were scavenged by the test compounds in all the models.

scholarly journals Isothermal Crystallization Kinetics of Poly(ethylene oxide)/Poly(ethylene glycol)-g-silica Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 648
Author(s):  
Xiangning Wen ◽  
Yunlan Su ◽  
Shaofan Li ◽  
Weilong Ju ◽  
Dujin Wang
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Poly Ethylene Glycol ◽  
Isothermal Crystallization Kinetics ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Kinetics Of

In this work, the crystallization kinetics of poly(ethylene oxide) (PEO) matrix included with poly(ethylene glycol) (PEG) grafted silica (PEG-g-SiO2) nanoparticles and bare SiO2 were systematically investigated by differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM) method. PEG-g-SiO2 can significantly increase the crystallinity and crystallization temperature of PEO matrix under the non-isothermal crystallization process. Pronounced effects of PEG-g-SiO2 on the crystalline morphology and crystallization rate of PEO were further characterized by employing spherulitic morphological observation and isothermal crystallization kinetics analysis. In contrast to the bare SiO2, PEG-g-SiO2 can be well dispersed in PEO matrix at low P/N (P: Molecular weight of matrix chains, N: Molecular weight of grafted chains), which is a key factor to enhance the primary nucleation rate. In particular, we found that the addition of PEG-g-SiO2 slows the spherulitic growth fronts compared to the neat PEO. It is speculated that the interfacial structure of the grafted PEG plays a key role in the formation of nuclei sites, thus ultimately determines the crystallization behavior of PEO PNCs and enhances the overall crystallization rate of the PEO nanocomposites.

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