Calculation of the induction period of thermal explosion

1997 ◽  
Vol 33 (1) ◽  
pp. 1-8
Author(s):  
R. S. Burkina ◽  
I. G. Dik
Keyword(s):  
Induction Period ◽  
Thermal Explosion

Effect of reactant consumption on the induction period and critical condition for a thermal explosion

1961 ◽  
Vol 262 (1309) ◽  
pp. 192-206 ◽  
Keyword(s):  
Theoretical Model ◽  
Theoretical Analysis ◽  
Induction Period ◽  
Thermal Explosion ◽  
Numerical Solutions ◽  
Critical Value ◽  
Maximum Temperature ◽  
Analytic Expressions ◽  
Effective Transfer ◽  
Explosion Parameter

An approximate theoretical analysis is given of a thermal explosion or ignition. The treat­ment leads to analytic expressions for the effect of reactant consumption on the critical explosion parameter and the induction period for a theoretical model, where spatial varia­tion of temperature is treated by considering only the maximum temperature at the centre of the reacting material and an effective transfer coefficient between the centre and the environment. The results are found to agree satisfactorily with detailed numerical solutions by Rice, Allen & Campbell (1935) and Todes & Melentiev (1939, 1940) where these are applicable. The effect of reactant consumption on the critical value of the explosion para­meter is shown to be more than twice that calculated by Frank-Kamenetskii (1946).

THE THERMAL EXPLOSION OF LEAD AZIDE

1947 ◽  
Vol 25b (6) ◽  
pp. 548-565 ◽  
Author(s):  
A. S. Hawkes ◽  
C. A. Winkler
Keyword(s):  
Induction Period ◽  
Thermal Explosion ◽  
Crystal Size ◽  
Dibutyl Phthalate ◽  
Volume Ratio ◽  
Lead Azide ◽  
Sharp Change ◽  
Induction Periods ◽  
Self Heating

The minimum explosion temperatures for service and dextrin azides (about 315 °C. and 275 °C., respectively) are increased considerably by increase of surface: volume ratio of the container and by compressing or wetting the charge with dibutyl phthalate before explosion. When wetted, the two azides were found to be similar in respect of minimum explosion temperatures and induction periods prior to explosion. Sensitization of service azide by preheating was found to be permanent. A limit to sensitization below the minimum explosion temperature was observed, and probably exists also for sensitization above this temperature. Wetting the charge with phthalate nullifies the sensitization. Although dextrin azide alone is more thermally sensitive than service azide, mixtures of the two containing 70% or more service azide show a sharp change to service azide properties; the mixtures apparently are not exploded by the dextrin azide they contain. The value of E in the expression [Formula: see text] + constant, where t is the induction period, has been determined for both the initial and final stages of reaction preceding explosion and found to be essentially unaltered. Minimum explosion temperature of single large crystals was shown to increase with crystal size. The data are interpreted as showing that the thermal explosion of lead azide may result from self-heating, the heat of the pre-explosion reaction not being sufficiently dissipated from the material.

Fibrin Formation: The Role of the Fibrinogen-Fibrin Monomer Complex

1976 ◽  
Vol 36 (01) ◽  
pp. 037-048 ◽  
Author(s):  
Eric P. Brass ◽  
Walter B. Forman ◽  
Robert V. Edwards ◽  
Olgierd Lindan
Keyword(s):  
Particle Size ◽  
Induction Period ◽  
Fibrin Clot ◽  
Clot Formation ◽  
Appreciable Amount ◽  
Buffer System ◽  
Homeostatic Mechanism ◽  
Fibrin Formation ◽  
Fibrin Monomer

SummaryThe process of fibrin formation using highly purified fibrinogen and thrombin was studied using laser fluctuation spectroscopy, a method that rapidly determines particle size in a solution. Two periods in fibrin clot formation were noted: an induction period during which no fibrin polymerization occurred and a period of rapid increase in particle size. Direct measurement of fibrin monomer polymerization and fibrinopeptide release showed no evidence of an induction period. These observations were best explained by a kinetic model for fibrin clot formation incorporating a reversible fibrinogen-fibrin monomer complex. In this model, the complex serves as a buffer system during the earliest phase of fibrin formation. This prevents the accumulation of free polymerizable fibrin monomer until an appreciable amount of fibrinogen has reacted with thrombin, at which point the fibrin monomer level rises rapidly and polymerization proceeds. Clinically, the complex may be a homeostatic mechanism preventing pathological clotting during periods of elevated fibrinogen.

Mechanism of the propagation step in the anionic polymerization of styrene

1980 ◽  
Vol 45 (4) ◽  
pp. 1047-1055 ◽  
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Experimental Data ◽  
Induction Period ◽  
Anionic Polymerization ◽  
Reactive Intermediate ◽  
Coordination Polymerization ◽  
Kinetic Dependence ◽  
Mathematical Solution ◽  
Slow Reaction

The paper is dealing with an investigation of the kinetic dependence of the propagation step in the anionic coordination polymerization of styrene in benzene at 303 K with "living" oligostyryllithium as initiator at the onset of the reaction. A short but distinct induction period was found, indicating a preceding slow reaction leading to the formation of a reactive intermediate, which behaves as the initiator of the reaction. Using results obtained in the first paper of this series, a new mechanism of propagation has been suggested, the mathematical solution of which is correlated with experimental data.

The effect of electrondonors on the polymerization kinetics of isoprene

1980 ◽  
Vol 45 (12) ◽  
pp. 3338-3346
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Induction Period ◽  
Ethyl Ether ◽  
Reaction Order ◽  
Propagation Rate ◽  
Reaction Scheme ◽  
Polymerization Kinetics ◽  
Polymerization Rate ◽  
Constant Concentration ◽  
Initial Concentration ◽  
Kinetics Of

The effect of small additions of 1-octene, butyl ethyl ether and triethylamine on the polymerization kinetics of isoprene (2-methyl-1,3-butadiene) in benzene initiated with butyllithium was investigated by employing the GLC analysis. The addition of 1-octane was reflected only in a shorter induction period of the reaction; the effect on the propagation rate was insignificant. With the increasing amount of butyl ethyl ether, the polymerization rate increases linearly, while the reaction order with respect to the concentration of triethylamine is variable and increases from 0.33 to 0.66 with the increasing concentration of the initiator. For a constant concentration of triethylamine, the reaction order with respect to the initial concentration of the initiator was found to vary considerably, reaching even negative values. A reaction scheme was suggested, taking into account the competition between two different solvates of alkyllithium.

Metathesis Polymerization of Phenylacetylene by Tungsten Aryloxo Complexes

1995 ◽  
Vol 60 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Hynek Balcar ◽  
Jan Sedláček ◽  
Marta Pacovská ◽  
Vratislav Blechta
Keyword(s):  
Molecular Weight ◽  
Catalytic Activity ◽  
Induction Period ◽  
Average Molecular Weight ◽  
Molar Fraction ◽  
Molar Ratio ◽  
Weight Average Molecular Weight ◽  
Polymer Yield ◽  
Positive Effect ◽  
Ligand Addition

Catalytic activity of the tungsten aryloxo complexes WCl5(OAr) and WOCl3(OAr), where Ar = 4-t-C4H9C6H4, 2,6-(t-C4H9)2C6H3, 2,6-Cl2C6H3, 2,4,6-Cl3C6H2, and 2,4,6-Br3C6H2 in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl5(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me4Sn, Bu4Sn, Ph4Sn, Bu3SnH) to WCl5(O-C6H2Cl3-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl3(O-C6H3Cl2-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).

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