Radiotracer Measurements of Sulfur Diffusion in Rubbers

1971 ◽  
Vol 44 (5) ◽  
pp. 1307-1315 ◽  
Author(s):  
M. Mozisek
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Elemental Sulfur ◽  
Butyl Rubber ◽  
In Cis ◽  
Sulfur Diffusion

Abstract The object of measurement was the diffusion of elemental sulfur labeled with the radioisotope S in representative types of rubber. The highest values of diffusion coefficient were found in cis-1,4 polybutadiene. The lowest measured value was found for butyl rubber. The activation energy, expressing the temperature dependence of the diffusion coefficients, ranges from 4 to 10 kcal mol-1. For some rubbers studied, the activation energy is to a certain degree dependent upon temperature. The values of the diffusion coefficients and the characteristic constants for their temperature dependence are related to the mobility of the macromolecular segments.

Oxygen Chemical Diffusion Coefficients of (U, Pu)O2-x

2017 ◽  
Vol 375 ◽  
pp. 84-90 ◽  
Author(s):  
Masashi Watanabe ◽  
Takeo Sunaoshi ◽  
Masato Kato
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Surface Reaction ◽  
Chemical Diffusion ◽  
Chemical Diffusion Coefficient ◽  
Thermo Gravimetry ◽  
Metal Ratio

The oxygen chemical diffusion coefficient in (U, Pu)O2-x was determined by thermo-gravimetry as functions of the Pu content, oxygen-to-metal ratio and temperature. The surface reaction was considered in the diffusion coefficient determination. The activation energy for the chemical diffusion coefficient was 60 kJ/mol and 65 kJ/mol, respectively, in (U0.8Pu0.2)O2-x and (U0.7Pu0.3)O2-x.

scholarly journals The mobility of sodium on tungsten

1935 ◽  
Vol 150 (869) ◽  
pp. 58-76 ◽  
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Work Function ◽  
Direct Measurement ◽  
Diffusion Coefficients ◽  
Condensation Coefficient ◽  
Alkali Earth ◽  
Adsorbed Films ◽  
A Value ◽  
Two Phases

Although the existence as well as some of the properties of adsorbed films of alkali and alkali earth metals on metals of higher work function have long been known, it is only recently that these films have been shown to be capable of migrating over the surface of the adsorbent, and that attempts have been made to measure diffusion coefficients and the activation energy associated with the diffusion. Langmuir and Taylor, investigating the properties of cæsium films, found it necessary to postulate that the cæsium was mobile in order to account for the high value (α ≅ 1.0) for the condensation coefficient on quite concentrated films. Later they were able to make a direct measurement of the diffusion coefficient. They obtained a value of D at 812° K of 3.4 x 10 -5 cm 2 secs -1 , and an activation energy of 0.61 volt. Langmuir has also shown that cæsium films exist in two phases and has measured the diffusion coefficient by following the movement of the boundary between these two phases.

Migration of Antioxidants and Accelerators in Natural and Synthetic Rubber II. Sulfenamide System Studies and Comparison of Age Resister Migration under Inert and Practical Conditions

1969 ◽  
Vol 42 (3) ◽  
pp. 892-902 ◽  
Author(s):  
James E. Lewis ◽  
Marvin L. Deviney ◽  
Lawrence E. Whittington
Keyword(s):  
Diffusion Coefficient ◽  
Carbon Black ◽  
Natural Rubber ◽  
Count Data ◽  
Diffusion Coefficients ◽  
Oil Migration ◽  
Carbon 14 ◽  
Synthetic Rubber ◽  
End Use ◽  
In Cis

Abstract Radiochemical techniques developed for studying extender oil migration in various elastomers have been adapted for use in investigating the migration of age resisters and curatives. This paper contains basic diffusion coefficient data for nine compounds including both staining and nonstaining antioxidants and members of the sulfenamide, thiazole and thiuram accelerator series. Techniques for synthesizing these age resisters and curatives in the carbon-14 and sulfur-35 labelled form are described. Migration was studied in natural rubber, SBR, cis-polybutadiene and EPT vulcanizates. Computer techniques were used to calculate diffusion coefficients from radiochemical count data. Results from preliminary migration studies under practical curing and end-use conditions are also presented. In the case of phenyl-2-naphthylamine migration in cis-polybutadiene, a pronounced decrease in diffusivity with increasing surface area of the carbon black filler was observed.

Temperature dependence of tracer diffusion coefficients in polystyrene

1986 ◽  
Vol 1 (1) ◽  
pp. 202-204 ◽  
Author(s):  
Peter F. Green ◽  
Edward J. Kramer
Keyword(s):  
Molecular Weight ◽  
Diffusion Coefficient ◽  
Shear Rate ◽  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Tracer Diffusion Coefficient ◽  
Critical Molecular Weight ◽  
Tracer Diffusion Coefficients ◽  
Monomeric Friction Coefficient

The temperature dependence of the tracer diffusion coefficient D* of long deuterated polystyrene (d-PS) chains of molecular weight M>Mc, where Mc is the critical molecular weight for entanglement, diffusing into highly entangled PS matrices, each of molecular weight P = 2×107, is studied using forward recoil spectrometry. It is found that the temperature dependence of D*/T, reflected primarily in the monomeric friction coefficient, is accurately described by a Vogel equation. The constants that are used to fit these results are independent of M and are the same as those used to fit the temperature dependence of the zero shear rate viscosity of polystyrene.

The Temperature Dependence of the Atoms Co Diffusion Coefficient in Pt80Co20(111) Alloy

2007 ◽  
Vol 265 ◽  
pp. 19-23
Author(s):  
M. Vasylyev ◽  
Vitaliy A. Tinkov ◽  
Sergey I. Sidorenko ◽  
S.M. Voloshko
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Surface Segregation ◽  
Surface Region ◽  
Near Surface ◽  
Kinetics Of

The method of Ionization Spectroscopy is used to study the thermo-induced kinetics of surface segregation of the Pt80Co20(111) alloy components. The temperature dependence of the Co diffusion coefficient in this alloy is determined. It is found that the value of the activation energy for the segregation of Co atoms in the near-surface region is close to the heat of sublimation of pure Co.

Fe tracer diffusion in L10 ordered FePt

2002 ◽  
Vol 753 ◽  
Author(s):  
Y. Nosé ◽  
T. Ikeda ◽  
H. Nakajima ◽  
K. Tanaka ◽  
H. Numakura
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Single Crystal ◽  
Diffusion Coefficients ◽  
Ion Beam ◽  
Tracer Diffusion ◽  
Ordered Structure ◽  
Tracer Diffusion Coefficient ◽  
Exponential Factor ◽  
Axis Direction

ABSTRACTTracer diffusion coefficient of 59Fe in FePt with the tetragonal L10 ordered structure has been measured by an ion-beam sputter-sectioning technique in the temperature range from 1173 to 1374 K. Anisotropy in diffusion has been studied using single-variant single-crystal specimens. The diffusion coefficient in the direction perpendicular to [001] axis (in the a-axis direction), Da, is larger than that in the [001] (c-axis) direction, Dc, as expected from the atomic arrangement of the L10 ordered structure. The ratio of the diffusion coefficients, Da/Dc, is 1.33.6 for Fe42Pt58 and smaller at higher temperatures. The activation energy for the diffusion is 259 ± 1 kJ/mol for Da and 309 ± 18 kJ/mol for Dc, while the pre-exponential factor is and , respectively in Fe42Pt58.

About Fe Diffusion in Cu

2012 ◽  
Vol 323-325 ◽  
pp. 171-176 ◽  
Author(s):  
D. Prokoshkina ◽  
A.O. Rodin ◽  
V. Esin
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Temperature Dependence ◽  
Boundary Diffusion ◽  
Bulk Diffusion ◽  
Grain Boundary Diffusion ◽  
Radiotracer Technique ◽  
Exponential Factor ◽  
Temperature Range

The temperature dependence of the bulk diffusion coefficient of Fe in Cu is determined by EDX in the temperature range from 923 to 1273 K, , m2/s. These results are different from that obtained earlier by radiotracer technique: activation energy is less by 30 kJ/mol and pre-exponential factor is 50 times smaller. Deviations from ideality of investigated solutions do not explain the differences; consequently, the thermodynamical factor would not responsible for such an effect. Fast grain boundary diffusion of Fe in Cu was not observed in the temperature range from 823 to 1073 K.

Infrared absorption spectroscopy of hydrogen and deuterium in CaO and SrO crystals

1989 ◽  
Vol 4 (1) ◽  
pp. 224-231 ◽  
Author(s):  
J. L. Park ◽  
R. González
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Diffusion Coefficients ◽  
Elevated Temperatures ◽  
Arrhenius Equation ◽  
Lithium Concentration ◽  
Infrared Absorption Spectroscopy ◽  
Infrared Absorption Spectra

Infrared absorption spectra have been used to characterize OH− and OD− ions at the surface and the bulk of undoped CaO, lithium doped CaO, and SrO crystals. Diffusion of deuterons from D2O vapor into these crystals was performed at elevated temperatures. Diffusion coefficients were obtained to be D (CaO) = 3 ⊠ 10−6 cm2/sec at 1773 K and D (SrO) = 4 ⊠ 10−7 cm2/sec at 1523 K. For the doped CaO crystal with lithium concentration of 310 ppm, the diffusion coefficient was measured to be D (CaO:Li) = 4 ⊠ 10−7 cm2/sec at 1473 K and the activation energy in the Arrhenius equation was estimated to be 1.7 eV.

Diffusion of 57Co in amorphous Fe–RE (RE = Dy, Tb, and Ce) and Fe–Si–B alloys

1993 ◽  
Vol 8 (9) ◽  
pp. 2231-2238 ◽  
Author(s):  
Kazumasa Yamada ◽  
Yoshiaki Iijima ◽  
Kazuaki Fukamichi
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Tracer Diffusion ◽  
Atomic Size ◽  
Exponential Factor ◽  
Dc Sputtering ◽  
The Matrix ◽  
Diffusion Temperature ◽  
Order Of Magnitude

Tracer diffusion of 57Co in amorphous Fe100−xDyx (x = 20–40), Fe75Tb25, Fe67Ce33, and Fe80Si6B14 alloys prepared by dc sputtering has been studied at temperatures of 523 and 573 K. In the Fe–Dy alloys the diffusion coefficient of 57Co shows a maximum at 33 at.% Dy. The magnitude of the diffusion coefficient of 57Co in Fe75Tb25 is nearly equal to that in Fe75Dy25, while those in Fe67Ce33 and Fe80Si6B14 are about one order of magnitude less than the values in Fe67Dy33 and Fe80Dy20. This suggests that the atomic size of the diffusant and the density of the matrix are dominant in the diffusion. Temperature dependence of the diffusion coefficient D of 57Co in the amorphous Fe75Dy25 alloy has been determined in the range from 493–673 K. It shows a linear Arrhenius relationship expressed by D = 5.7 × 10−2 exp(−199 kJ mol−1/RT) m2 s−1. The magnitudes of the pre-exponential factor and the activation energy suggest that the cobalt tracer atoms in the amorphous Fe75Dy25 alloy diffuse by an interstitial-like mechanism.

Kinetic isotherms of cyclohexane on active carbon supersorbon

1979 ◽  
Vol 44 (12) ◽  
pp. 3464-3468
Author(s):  
Zdeněk Sedláček
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Active Carbon ◽  
Enthalpy Of Vaporization ◽  
Probable Mechanism

The kinetic isotherm makes it possible to compute the value of diffusion coefficient and, from its temperature dependence, to calculate the activation energy of the adsorbate transfer in the adsorbent pores. The data of kinetic isotherms have been taken over from our previous paper. On the basis of comparison of the activation energy with the isosteric heats and with enthalpy of vaporization we can judge of a probable mechanism of transfer.

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