The Sulfonation of Natural Rubber

1951 ◽  
Vol 24 (4) ◽  
pp. 921-923
Author(s):  
G. J. van Amerongen
Keyword(s):  
Sulfur Dioxide ◽  
Natural Rubber ◽  
Experimental Results ◽  
Chain Reaction ◽  
A Chain

Abstract Like many olefins, natural rubber is capable of reacting with sulfur dioxide, with formation of a sulfone. The reaction is a chain reaction which is started by certain catalysts. The structure of the rubber sulfone is: (see PDF for diagram) and the theoretical proportion of sulfur is 24.2 per cent. Table I gives some experimental results obtained in the reaction of rubber with sulfur dioxide.

Oxidative Scission of Natural Polyisoprenes in Solution

1966 ◽  
Vol 39 (3) ◽  
pp. 530-536
Author(s):  
C. L. M. Bell
Keyword(s):  
Natural Rubber ◽  
Detailed Analysis ◽  
Chain Reaction ◽  
Polymer Backbone ◽  
Gutta Percha ◽  
Oxidation Chain ◽  
A Chain ◽  
Reaction Chain

Abstract Polyisoprenes are oxidized by a chain reaction in which a large number of oxygen molecules are absorbed for each reaction chain started. During the oxidation, scission of the polymer backbone takes place. Using solutions of natural rubber and gutta percha, measurements of the relative amounts of oxygen absorbed and scission produced indicate that most scission occurs during propagation of the oxidation chain. However, more detailed analysis of the data indicates that scission also occurs nearly every time an oxidation chain is terminated.

Observations on a Relationship between Steroid Metabolism and the Concentration of Plasma Fibrinogen

1963 ◽  
Vol 10 (02) ◽  
pp. 400-405 ◽  
Author(s):  
B. A Amundson ◽  
L. O Pilgeram
Keyword(s):  
Blood Coagulation ◽  
Methyl Ether ◽  
Broad Spectrum ◽  
Human Subjects ◽  
Plasma Fibrinogen ◽  
Steroid Metabolism ◽  
Specific Site ◽  
Chain Reaction ◽  
Normal Human ◽  
A Chain

SummaryEnovid (5 mg norethynodrel and 0.075 mg ethynylestradiol-3-methyl ether) therapy in young normal human subjects causes an increase in plasma fibrinogen of 32.4% (P >C 0.001). Consideration of this effect together with other effects of Enovid on the activity of specific blood coagulatory factors suggests that the steroids are exerting their effect at a specific site of the blood coagulation and/or fibrinolytic system. The broad spectrum of changes which are induced by the steroids may be attributed to a combination of a chain reaction and feed-back control.

scholarly journals Pathogenesis and Management of COVID-19

2021 ◽  
Vol 11 (2) ◽  
pp. 77-93
Author(s):  
Khalid O. Alfarouk ◽  
Sari T. S. AlHoufie ◽  
Samrein B. M. Ahmed ◽  
Mona Shabana ◽  
Ahmed Ahmed ◽  
...  
Keyword(s):  
Multiple Organ Failure ◽  
Human Body ◽  
Inflammatory Mediators ◽  
Expression Patterns ◽  
Multiple Organ ◽  
Cytokine Storm ◽  
Chain Reaction ◽  
Road Map ◽  
A Chain ◽  
Global War

COVID-19, occurring due to SARS-COV-2 infection, is the most recent pandemic disease that has led to three million deaths at the time of writing. A great deal of effort has been directed towards altering the virus trajectory and/or managing the interactions of the virus with its subsequent targets in the human body; these interactions can lead to a chain reaction-like state manifested by a cytokine storm and progress to multiple organ failure. During cytokine storms the ratio of pro-inflammatory to anti-inflammatory mediators is generally increased, which contributes to the instigation of hyper-inflammation and confers advantages to the virus. Because cytokine expression patterns fluctuate from one person to another and even within the same person from one time to another, we suggest a road map of COVID-19 management using an individual approach instead of focusing on the blockbuster process (one treatment for most people, if not all). Here, we highlight the biology of the virus, study the interaction between the virus and humans, and present potential pharmacological and non-pharmacological modulators that might contribute to the global war against SARS-COV-2. We suggest an algorithmic roadmap to manage COVID-19.

Relation between Molecular Weights and Physical Properties of Rubber Fractions

1941 ◽  
Vol 14 (3) ◽  
pp. 580-589 ◽  
Author(s):  
G. Gee ◽  
L. R. G. Treloar
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Elastic Properties ◽  
Elastic Material ◽  
Experimental Results ◽  
Molecular Weights ◽  
High Elasticity ◽  
Latex Rubber

Abstract As high elasticity is a property possessed only by substances of high molecular weight, it is of interest to enquire into the relation between the elastic properties of a highly elastic material such as rubber and its molecular weight. An investigation on these lines has been made possible through the work of Bloomfield and Farmer, who have succeeded in separating natural rubber into fractions having different average molecular weights. The more important physical properties of these fractions have been examined with the object of determining which of the properties are dependent on molecular weight and which are not. Fairly extensive observations were made on the fractions from latex rubber referred to as Nos. 2, 3 and 4 by Bloomfield and Farmer, and some less extensive observations were carried out on the less oxygenated portion of fraction No. 1 obtained from crepe rubber (called hereafter 1b) . Before considering these experimental results, and their relation to the molecular weights of the fractions, it will be necessary to refer briefly to the methods used for the molecular-weight determinations, and to discuss the significance of the figures obtained.

Influence of initiation mode on stability and control of a chain reaction

1980 ◽  
Vol 20 (18) ◽  
pp. 1197-1204 ◽  
Author(s):  
H. T. Chen ◽  
P. A. Chartier ◽  
S. Setthachayanon
Keyword(s):  
Chain Reaction ◽  
Stability And Control ◽  
A Chain ◽  
And Control

scholarly journals On the explosion of chain-thermal reactions

1982 ◽  
Vol 24 (2) ◽  
pp. 194-202 ◽  
Author(s):  
R. O. Ayeni
Keyword(s):  
Activation Energy ◽  
Asymptotic Analysis ◽  
Upper Bound ◽  
Homogeneous Model ◽  
Chain Reaction ◽  
Isothermal Reaction ◽  
Thermal Reactions ◽  
Spatially Homogeneous ◽  
Branched Chain ◽  
A Chain

AbstractA chain reaction of oxygen (reactant) and hydrogen (active intermediary) with mtrosyl chloride (sensitizer) as a catalyst may be modelled mathematically as a non-isothermal reaction. In this paper we present an asymptotic analysis of a spatially homogeneous model of a non-isothermal branched-chain reaction. Of particular interest is the so-called explosion time and we provide an upper bound for it as a function of the activation energy which can vary over all positive values. We also establish a bound on the temperature when the activation energy is finite.

scholarly journals Synthesis of polylactic acid-diol (PLA-diol) from lactic acid and 1,4-butanediol

2016 ◽  
Vol 19 (4) ◽  
pp. 58-65
Author(s):  
Ha Thi Thai La
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Polyethylene Glycol ◽  
1H Nmr ◽  
Biodegradable Polymer ◽  
Average Molecular Weight ◽  
Chain Extension ◽  
Structure And Properties ◽  
Chain Reaction ◽  
A Chain

In this research, the PLA-diol were synthesized from lactic acid (LA) and 1.4 butanediols (BD) with a tin octoate Sn(Oct)2 catalyst at a temperature of 180 °C and the pressure 5 mmHg. The structure and properties of PLA-diol are analyzed by the following methods: GPC, 1H-NMR and DSC. As a result, with the change in the content of Sn (Oct)2 from 0.1 to 1.0%, the molecular weight Mn of PLA - diol increased gradually from 4.119,2 to 7.359,6 g / mol . In addition, the BD content increased from 2.0% to 5.0%, the average molecular weight of the product decreased gradually from 7.536,9 g / mol to 4.735 g / mol, respectively. This change will affect the ability to use PLA-diol in the next denaturation research to apply in the field of biodegradable polymer such as copolymer with polyurethane, copolymer with polyethylene glycol diacid, or chain extension with other polymer in a chain reaction,...

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