Relation between activation energy and induction in rubber sulfur vulcanization: An experimental study

2020 ◽  
Vol 138 (12) ◽  
pp. 50073
Author(s):  
Gabriele Milani ◽  
Federico Milani
Keyword(s):  
Activation Energy ◽  
Experimental Study ◽  
Sulfur Vulcanization

THEORETICAL AND EXPERIMENTAL STUDY ON THE REGIOSELECTIVITY OF ACRYLONITRILE AND METHYLMETHACRYLATE 1,3-DIPOLAR CYCLOADDITION TO SOME NITRILIMINES

2012 ◽  
Vol 11 (01) ◽  
pp. 99-109 ◽  
Author(s):  
F. MOEINPOUR ◽  
M. BAKAVOLI ◽  
A. DAVOODNIA ◽  
A. MORSALI
Keyword(s):  
Activation Energy ◽  
Density Functional Theory ◽  
Experimental Study ◽  
Density Functional ◽  
Chemical Shifts ◽  
Dipolar Cycloaddition ◽  
Functional Theory ◽  
Reactivity Indexes ◽  
C Nmr

1,3-dipolar cycloaddition between acrylonitrile and methylmethacrylate with two N-(4-bromophenyl)-C-(4-substituted) nitrilimines which were generated in situ afforded the new pyrazoles. The regioselectivity and reactivity of these reactions has been investigated on the basis of density functional theory (DFT)-based reactivity indexes and activation energy calculations. The theoretical 13C NMR chemical shifts of the cycloadducts which were obtained by GIAO method were comparable with the observed values.

scholarly journals Anomalously low activation energy of nanoconfined MgCO3 precipitation

2019 ◽  
Vol 55 (48) ◽  
pp. 6835-6837 ◽  
Author(s):  
Quin R. S. Miller ◽  
John P. Kaszuba ◽  
Herbert T. Schaef ◽  
Mark E. Bowden ◽  
B. Peter McGrail ◽  
...  
Keyword(s):  
Activation Energy ◽  
Experimental Study ◽  
Nucleation And Growth ◽  
Growth Processes

Experimental study of nanoconfined MgCO3 nucleation and growth processes reveals elevated kinetics due to less strongly hydrated Mg2+.

scholarly journals Experimental Study of Free Energy of Activation of Flow and Grunberg-Nissan Parameters in Binary Liquid Mixtures

BIBECHANA ◽  
1970 ◽  
Vol 6 ◽  
pp. 9-14
Author(s):  
IS Jha ◽  
RP Koirala ◽  
D Adhikari
Keyword(s):  
Activation Energy ◽  
Experimental Study ◽  
Free Energy ◽  
Binary Mixtures ◽  
Molecular Interactions ◽  
Liquid Mixtures ◽  
Binary Liquid Mixtures ◽  
Binary Liquid ◽  
Free Energy Of Activation ◽  
Excess Viscosities

The binary mixtures of cabontetrachloride with isobutylmethylketone and benzaldehyde were studied at 308.15 by measuring viscosities and densities. The derived and excess viscosities, activation energy of flow and Grunberg-Nissan parameters have been calculated. It was found that these parameters are satisfactorily used to predict the strength and nature of molecular interactions. It was found that the strength of interactions in the systems studied is in the following order: CCl4 + IBMK>CCl4 + BDKeywords: Binary liquid; benzaldehyde; carbontetrachlorideDOI: 10.3126/bibechana.v6i0.3932BIBECHANA Vol. 6, March 2010 pp.9-14

The friction and the mechanical properties of solid krypton

1955 ◽  
Vol 228 (1172) ◽  
pp. 1-9 ◽  
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Experimental Study ◽  
Melting Point ◽  
Critical Shear Stress ◽  
Liquid Hydrogen ◽  
Surface Forces ◽  
Creep Measurements ◽  
Solid Krypton ◽  
Frictional Behaviour

An experimental study has been made of the frictional behaviour and of the hardness of solid krypton. It is found that the friction is nearly independent of load over the range investigated. At temperatures close to the melting point the friction is very low and the frictional behaviour is similar to that of ice. When the temperature is well below the melting point the friction is much higher, about u = 0.7, although the surface forces of the van der Waals crystal must be weak. An explanation of this high friction is suggested by the measurements of hardness. These show that the solid is extremely soft at temperatures near the melting point. Even at liquid-hydrogen temperatures, where the creep becomes negligible, the yield pressure is only about 0.3 Kg/mm 2 . Thus large areas of contact are formed between two surfaces which are placed together under load. It is suggested that, as with other plastic solids, the friction is primarily determined by the shearing of these contact areas formed by local plastic flow. An estimate is made of the activation energy for flow, deduced from creep measurements, giving the low value of about 1 to 2 kcal/gmol., and an approximate value of 4 x 10 6 dyn/cm 2 is computed for the critical shear stress of undeformed krypton at liquid-hydrogen temperature.

Vulcanization of Elastomers. 28. Vulcanization of Natural and Synthetic Rubbers with Sulfur in the Absence of Accelerators. I

1960 ◽  
Vol 33 (4) ◽  
pp. 1051-1061
Author(s):  
Elisabeth Echte ◽  
Walter Scheele ◽  
Sigrun Sonnenberg
Keyword(s):  
Activation Energy ◽  
Natural Rubber ◽  
Zero Order ◽  
Sulfur Concentration ◽  
Kcal Mole ◽  
Sulfur Solubility ◽  
Temperature Relation ◽  
Sulfur Vulcanization ◽  
Rate Relationship ◽  
Kinetics Of

Abstract The decrease of sulfur concentration in the reaction of sulfur with natural rubber was studied. The following was found : 1. Sulfur decrease follows the 0.6th order law independent of temperature as long as the sulfur is dissolved in the gum (temperature!). From the rate-temperature relation, an activation energy of 35 kcal/mole is calculated. 2. In an investigation of the kinetics of sulfur concentration at constant temperature but increasing starting concentration, the following two cases can be differentiated : a) As long as the sulfur is soluble in the gum, sulfur decrease still follows the 0.6th order, possibly due to autocatalysis ; the linear relationship between starting rate and starting concentration shows that the process is 1st order with respect to the concentration; this may be the consequence of a thermal, rate determining cleavage of the S8 ring. b) As the sulfur at higher concentration is only incompletely soluble in the gum, conversion curves with points of inflection are found ; this becomes more pronounced at higher concentration. At the start of the reaction one finds an autocatalytic sulfur decrease basically of zero order; in the latter part of the reaction after passing the point of inflection a 0.6th order is observed, as in the range of complete sulfur solubility. 3. A discrepancy between the time law and the concentration-rate relationship is found in pure as well as accelerated sulfur vulcanization ; these conditions are compared and discussed.

Effect of Temperature on the Course of Thiuram-Accelerated Sulfur Vulcanization

1976 ◽  
Vol 49 (5) ◽  
pp. 1193-1199 ◽  
Author(s):  
V. Ducháček
Keyword(s):  
Activation Energy ◽  
Zinc Oxide ◽  
Activation Energies ◽  
Effect Of Temperature ◽  
Crosslinking Reaction ◽  
Curing Process ◽  
Sulfur Vulcanization ◽  
Good Accordance

Abstract These results confirm the validity of our theory of thiuram-accelerated sulfur vulcanization supposing that ZnDMDC arising from TMTD and zinc oxide is the actual accelerator in this type of curing system. The formation of ZnDMDC from TMTD during the curing process affects particularly the slow crosslinking reaction. Therefore, the activation energy of slow crosslinking is in very good accordance with the activation energy of TMTD decrease, and its value differs significantly from the activation energies of fast crosslinking and degradation. Simultaneously, these facts answer the question why the shape of the cure curves depends strongly on the temperature of cure.

Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

1995 ◽  
Vol 53 ◽  
pp. 636-637
Author(s):  
Norio Baba ◽  
Norihiko Ichise ◽  
Syunya Watanabe
Keyword(s):  
Experimental Study ◽  
Spherical Aberration ◽  
Incident Beam ◽  
Optical Parameters ◽  
Beam Tilting ◽  
Illumination Method ◽  
Restoration Method ◽  
Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

An Experimental Study of Some Properties of Stuttered Words

1962 ◽  
Vol 5 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Bruce Quarrington ◽  
Jerome Conway ◽  
Nathan Siegel
Keyword(s):  
Experimental Study
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