Effect of temperature on the pressure dependence of helium solubility in vitreous silica

1978 ◽  
Vol 49 (9) ◽  
pp. 4958-4960 ◽  
Author(s):  
J. E. Shelby
Keyword(s):  
Pressure Dependence ◽  
Vitreous Silica ◽  
Effect Of Temperature

scholarly journals Effect of Temperature and Pressure on Segmental Relaxation in Polymethylphenylsiloxane

2003 ◽  
Vol 76 (5) ◽  
pp. 1106-1115 ◽  
Author(s):  
S. Pawlus ◽  
S. J. Rzoska ◽  
J. Ziolo ◽  
M. Paluch ◽  
C. M. Roland
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Pressure Dependence ◽  
Activation Volume ◽  
Relaxation Times ◽  
Effect Of Temperature ◽  
Loss Peak ◽  
Glass Transition Temperatures ◽  
Segmental Relaxation ◽  
Temperature And Pressure

Abstract Segmental relaxation in a series of polymethylphenylsiloxanes (PMPS) was studied using dielectric spectroscopy. The measurements covered a temperature range of more than 40 deg at pressures from ambient to 115 MPa. The results confirmed that the shape of the loss peak is independent of temperature, pressure and molecular weight. Consequently, the Tg -scaled dependence of the relaxation times was also independent of molecular weight. The pressure dependence of the relaxation times was characterized by means of the activation volume. This quantity changes markedly with pressure at a given temperature. However, the activation volume at the respective glass transition temperatures of the PMPS are essentially invariant to molecular weight. Finally, we measured the dependence of Tg on pressure, with the results well-described by the Andersson equation.

Effect of gas composition on the pressure dependence of helium solubility in vitreous silica

1976 ◽  
Vol 47 (9) ◽  
pp. 3952-3955 ◽  
Author(s):  
J. E. Shelby ◽  
S. C. Keeton ◽  
J. J. Iannucci
Keyword(s):  
Pressure Dependence ◽  
Vitreous Silica ◽  
Gas Composition

Mathematical Modeling and Investigation on the Temperature and Pressure Dependency of Permeation and Membrane Separation Performance for Natural gas Treatment

2016 ◽  
Vol 11 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Seyed Saeid Hosseini ◽  
Javad Aminian Dehkordi ◽  
Prodip K. Kundu
Keyword(s):  
Experimental Data ◽  
Pressure Dependence ◽  
Hollow Fiber ◽  
Hollow Fiber Membrane ◽  
Effect Of Temperature ◽  
Separation Performance ◽  
Gas Treatment ◽  
Pressure Dependency ◽  
Temperature And Pressure ◽  
Membrane Permeance

Abstract Due to special features, modules comprising asymmetric hollow fiber membranes are widely used in various industrial gas separation processes. Accordingly, numerous mathematical models have been proposed for predicting and analyzing the performance. However, majority of the proposed models for this purpose assume that membrane permeance remains constant upon changes in temperature and pressure. In this study, a mathematical model is proposed by taking into account non-ideal effects including changes in pressure and temperature in both sides of hollow fibers, concentration polarization and Joule-Thomson effects. Finite element method is employed to solve the governing equations and model is validated using experimental data. The effect of temperature and pressure dependency of permeance and separation performance of hollow fiber membrane modules is investigated in the case of CO2/CH4. The effect of temperature and pressure dependence of membrane permeance is studied by using type Arrhenius type and partial immobilization equations to understand which form of the equations fits experimental data best. Findings reveal that the prediction of membrane performance for CO2/CH4 separation is highly related to pressure and temperature; the models considering temperature and pressure dependence of membrane permeance match experimental data with higher accuracy. Also, results suggest that partial immobilization model represents a better prediction to the experimental data than Arrhenius type equation.

The catalytic fission of the carbon-nitrogen bond II. The reactions of ethylamine and hydrogen on evaporated metal films

1958 ◽  
Vol 244 (1238) ◽  
pp. 398-410 ◽  
Keyword(s):  
Pressure Dependence ◽  
Reaction Mechanisms ◽  
Metal Films ◽  
Activation Energies ◽  
Effect Of Temperature ◽  
Gold Films ◽  
Rate Determining Step ◽  
The Common ◽  
Nitrogen Bond ◽  
And Tungsten

The catalytic fission of the C—N bond of ethylamine in hydrogen led to two main reactions: platinum films favoured reaction I, to ammonia and ethane; nickel, palladium and gold films favoured reaction II, producing ammonia and diethylamine and also triethylamine by further reaction of the first products. Both types of reaction occurred on rhodium and tungsten films. The effect of temperature was studied and the values of the activation energies indicated that the fission of the C—N bond was the common rate-determining step for the various pro­cesses. Increase of pressure of ethylamine caused reaction II to occur on platinum films and eventually to predominate over reaction I. Although the rate of fission of the C—N bond on platinum was not influenced by the pressure of ethylamine, the ratio of the rates of reaction II and I depended on the second power of this pressure. Reaction mechanisms are discussed and the pressure dependence of the rates on platinum considered in terms of differing types of adsorption of the amine. The activity of the various catalysts is compared and discussed with regard to their ability to break the C—N bond in ethylamine. It was found that ethylamine was more easily decomposed than methylamine on all the metals which were common to this investigation and to the previous work on the decomposition of methylamine.

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