Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Inversion temperatures for the

Figure 4. The [ OH]/[ OH] branching ratios versus inverse temperature for the H 02 + reaction. Reprinted with permission from [41]. Copyright 1994 American Chemical Society. Figure 4. The [ OH]/[ OH] branching ratios versus inverse temperature for the H 02 + reaction. Reprinted with permission from [41]. Copyright 1994 American Chemical Society.
Using the usual fitting procedure [ 1 ], the dependence of the relaxation rate on the inverse temperature for the alpha and beta relaxation process is extracted (Fig. 25). The dynamic glass transition becomes more than one order of magnitude faster with increasing confinement, corresponding to a shift of 36 K to lower temperatures (Fig. 26). The thickness dependence of both the alpha relaxation time (at a constant temperature of 427 K) and the maximum... [Pg.616]

Fig. 11.1 The Haven ratios, plotted against inverse temperature, for the diffusion of silver ions in three solid ionic conductors Ag2S, Ag2Se, and Ag2Te. (From H. Okazaki, J. Phys. Soc. Jpn, 43, 213 (1977).)... Fig. 11.1 The Haven ratios, plotted against inverse temperature, for the diffusion of silver ions in three solid ionic conductors Ag2S, Ag2Se, and Ag2Te. (From H. Okazaki, J. Phys. Soc. Jpn, 43, 213 (1977).)...
Fig. 2.28 Delayed PFB exciton fluorescence from the F8 PFB blend from Fig. 2.27 versus inverse temperature for the detection wavelengths 420 nm (squares) and 435 nm (circles). The data was calculated from the spectra of Fig.2.27(b) by assuming negligible back-transfer at 150K, i.e. the 150K spectrum to represent only exciplex emission. Subtracting this from the higher temperature spectra then yields an estimate for the delayed exciton... Fig. 2.28 Delayed PFB exciton fluorescence from the F8 PFB blend from Fig. 2.27 versus inverse temperature for the detection wavelengths 420 nm (squares) and 435 nm (circles). The data was calculated from the spectra of Fig.2.27(b) by assuming negligible back-transfer at 150K, i.e. the 150K spectrum to represent only exciplex emission. Subtracting this from the higher temperature spectra then yields an estimate for the delayed exciton...
Figure 7 Scheme of the dynamics taking place at the glass transition for amorphous polymers, (a) Imaginary part e" of the complex dielectric function vs. frequency for two temperatures Ti and T2- The different processes are indicated, (b) Relaxation map (relaxation rate vs. inverse temperature) for the different processes, (c) Thermal glass transition where the specific heat capacity is plotted vs. inverse temperature. [Pg.206]

Figure 8 Relaxation rates vp vs. inverse temperature for the dynamic glass transition of PMPS as obtained by the different techniques , dielectric spectroscopy , thermal spectroscopy , neutron spectroscopy. The data obtained from neutron scattering depend on the momentum transfer 0. In addition to the dynamic glass transition, the relaxation rates for the methyl group rotation for 0=1.8A ( ) are given. The line is a fit of the Arrhenius equation to the data of the methyl group rotation ( A=8.3kJmoL, log(L = 12.5 Hz). The inset gives dielectric loss vs. frequency for PMPS at different temperatures 212.2 K o, 215.2 K ), 219.2 K A, 225.2 K 0, 235.2 K V, 241.2 K +, 257.41 K , 283.1 K. The errors of the measurements are smaller than the size of the symbols. Lines are guides to the eyes. Figure 8 Relaxation rates vp vs. inverse temperature for the dynamic glass transition of PMPS as obtained by the different techniques , dielectric spectroscopy , thermal spectroscopy , neutron spectroscopy. The data obtained from neutron scattering depend on the momentum transfer 0. In addition to the dynamic glass transition, the relaxation rates for the methyl group rotation for 0=1.8A ( ) are given. The line is a fit of the Arrhenius equation to the data of the methyl group rotation ( A=8.3kJmoL, log(L = 12.5 Hz). The inset gives dielectric loss vs. frequency for PMPS at different temperatures 212.2 K o, 215.2 K ), 219.2 K A, 225.2 K 0, 235.2 K V, 241.2 K +, 257.41 K , 283.1 K. The errors of the measurements are smaller than the size of the symbols. Lines are guides to the eyes.
Diflusion coefficient versus inverse temperature for the PC-D3PO4 (23%) gel electrolyte. [Pg.65]

Obviously, the inversion phenomenon can be defined only for a constant drying rate period. Nevertheless, several research groups have attempted to extend this definition also to a falling rate period. Prachayawarakom et al. (2002), for example, have reported the inversion temperature for the whole drying process (combined... [Pg.93]

Fig. 7.30 (a) Normalized mean-square gyration radius at constant — 4>v) = 0.9 plotted vs. inverse temperature for the model of Fig. 7.3 on the mple cubic lattice, choosing N = 32,4>v = 0.6, (.ab = 0, iAA = BB = —f Tbe crosses refer to the majority component (A), the circles to the minority component (B). The largest value of e/kgT shown corresponds to a state at the coexistence curve. (From Sariban and Binder. ) (b) Mean-square gyration radius of an isolated B chain in an A-rich matrix, for the same model as in (a) but three chain lengths. Note that the inverse critical temperatures for these mixtures are e/fcaTss 0.1 (A = 16),0.092(1V = 32), and 0.049(A = 64), respectively. (From Sariban and Binder. ")... [Pg.406]

Fig. 6 Inverse susceptibility S"i(0) and inverse square of the correlation length versus inverse temperature for the critical LCST high molar volume blend dPS/PVME. The solid lines represent a fit of the corresponding crossover functions. The mean field approximation is visible in the insets, the Ising behavior by the dashed lines... Fig. 6 Inverse susceptibility S"i(0) and inverse square of the correlation length versus inverse temperature for the critical LCST high molar volume blend dPS/PVME. The solid lines represent a fit of the corresponding crossover functions. The mean field approximation is visible in the insets, the Ising behavior by the dashed lines...
Fig. 12.2 Loss part of the dielectric permittivity normalized to its maximum value, as a function of temperature for PS nanospheres obtained by BDS at 0.5 Hz and a heating rate of 3 K.min with the following diameters 379 nm blue circles), 286 nm (green up-triangles), 200 nm (violet diamonds), 130 nm (red down-triangles), and for bulk PS (black crosses). The inset shows the typical relaxation time of the relatively fast component of the dynamics as a function of the inverse temperature for the nanospheres with diameter of 130 nm. (reprinted with permission from ref. [193])... Fig. 12.2 Loss part of the dielectric permittivity normalized to its maximum value, as a function of temperature for PS nanospheres obtained by BDS at 0.5 Hz and a heating rate of 3 K.min with the following diameters 379 nm blue circles), 286 nm (green up-triangles), 200 nm (violet diamonds), 130 nm (red down-triangles), and for bulk PS (black crosses). The inset shows the typical relaxation time of the relatively fast component of the dynamics as a function of the inverse temperature for the nanospheres with diameter of 130 nm. (reprinted with permission from ref. [193])...
Figure B2.4.2. Eyring plot of log(rate/7) versus (1/7), where Jis absolute temperature, for the cis-trans isomerism of the aldehyde group in fiirfiiral. Rates were obtained from tln-ee different experiments measurements (squares), bandshapes (triangles) and selective inversions (circles). The line is a linear regression to the data. The slope of the line is A H IR, and the intercept at 1/J = 0 is A S IR, where R is the gas constant. A and A are the enthalpy and entropy of activation, according to equation (B2.4.1)... Figure B2.4.2. Eyring plot of log(rate/7) versus (1/7), where Jis absolute temperature, for the cis-trans isomerism of the aldehyde group in fiirfiiral. Rates were obtained from tln-ee different experiments measurements (squares), bandshapes (triangles) and selective inversions (circles). The line is a linear regression to the data. The slope of the line is A H IR, and the intercept at 1/J = 0 is A S IR, where R is the gas constant. A and A are the enthalpy and entropy of activation, according to equation (B2.4.1)...
Taylor and Marsh (7) investigated the long-term characteristics of temperature inversions and mixed layers in the lower atmosphere to produce an inversion climatology for the Los Angeles basin. In this area the cooler ocean currents produce an elevated inversion that is nearly always present and traps the pollutants released over the area within a layer seldom deeper than 1200 m and frequently much shallower. [Pg.357]

Subsequent studies and applications with ether carboxylates have been published [73]. Phase inversion temperature measurements, which can be used to select surfactants for enhanced oil recovery, showed good results when the phase inversion temperature of the system was just below the reservoir temperature [184]. [Pg.343]

Results described in the literature have resulted in several patents, such as one for the improvement of the transport of viscous crude oil by microemulsions based on ether carboxylates [195], or combination with ether sulfate and nonionics [196], or several anionics, amphoterics, and nonionics [197] increased oil recovery with ether carboxylates and ethersulfonates [198] increased inversion temperature of the emulsion above the reservoir temperature by ether carboxylates [199], or systems based on ether carboxylate and sulfonate [200] or polyglucosylsorbitol fatty acid ester [201] and eventually cosolvents which are not susceptible for temperature changes. Ether carboxylates also show an improvement when used in a C02 drive process [202] or at recovery by steam flooding [203]. [Pg.344]

Figure 3.6. Example of the type of kinetic information available for the catalytic reduction of NO on rhodium single-crystal surfaces under atmospheric conditions. The data in this figure correspond to specific rates for C02, N20, and N2 formation over Rh(l 11) as a function of inverse temperature for two NO + CO mixtures PNO = 0.6 mbar and Pco — 3 mbar (A), and Pno — Pco = 4 mbar (B) [55]. The selectivity of the reaction in this case proved to be approximately constant independent of surface temperature at high NO pressures, but to change significantly below Pno 1 mbar. This highlights the dangers of extrapolating data from experiments under vacuum to more realistic pressure conditions. (Reproduced with permission from the American Chemical Society, Copyright 1995). Figure 3.6. Example of the type of kinetic information available for the catalytic reduction of NO on rhodium single-crystal surfaces under atmospheric conditions. The data in this figure correspond to specific rates for C02, N20, and N2 formation over Rh(l 11) as a function of inverse temperature for two NO + CO mixtures PNO = 0.6 mbar and Pco — 3 mbar (A), and Pno — Pco = 4 mbar (B) [55]. The selectivity of the reaction in this case proved to be approximately constant independent of surface temperature at high NO pressures, but to change significantly below Pno 1 mbar. This highlights the dangers of extrapolating data from experiments under vacuum to more realistic pressure conditions. (Reproduced with permission from the American Chemical Society, Copyright 1995).
Optimal Salinities Phase inversions at optimal salinity were assessed routinely by salt titrations into systems maintained at constant temperature. For the Leonox IOS surfactant system, increasing levels of salinity were necessary to cause the emulsion state to phase invert as the alkane molecular weight increased (Figure 11). Ihe initial conductivity value at the condition where zero salt had been added may in part reflect the salt contamination naturally present within the supplied formulation. Ihe internal olefin sulphonate species again revealed a linear relationship between EACN and optimal salinity as did all ionic formulations under test (see Figures 12 and 13, plus Table III). Ihe estimation of EACN values for both toluene... [Pg.315]

Figure 10.2 Arrhenius plot of the natural logarithm of the relaxation time extracted from the ac susceptibility data as a function of the inverse temperature for 1 at different external fields as indicated. (Reprinted from Ref. [6]. Copyright (2009) American Chemical Society.)... Figure 10.2 Arrhenius plot of the natural logarithm of the relaxation time extracted from the ac susceptibility data as a function of the inverse temperature for 1 at different external fields as indicated. (Reprinted from Ref. [6]. Copyright (2009) American Chemical Society.)...
Fig. 10. Steady state concentration of the V2H acceptor as a function of the absolute inverse temperature for two dislocation-free samples from different crystals. The dashed vertical line indicates the temperature limit above which an irreversible loss of V2H occurs. The dotted line corresponds to 1.04 x 1019 exp (- 0.71 eV/kT) cm-3. Fig. 10. Steady state concentration of the V2H acceptor as a function of the absolute inverse temperature for two dislocation-free samples from different crystals. The dashed vertical line indicates the temperature limit above which an irreversible loss of V2H occurs. The dotted line corresponds to 1.04 x 1019 exp (- 0.71 eV/kT) cm-3.
Figure 16. The rate constant for the decreasing heat release with time, r1Q of Equation 3" versus the inverse absolute temperature for the commercial boards of Figure 14. (Reproduced with permission from ref. 10. Copyright 1989 De Gruyter.)... Figure 16. The rate constant for the decreasing heat release with time, r1Q of Equation 3" versus the inverse absolute temperature for the commercial boards of Figure 14. (Reproduced with permission from ref. 10. Copyright 1989 De Gruyter.)...
Cyclobutenyl carbocations have been under study in our laboratory for some years (11). In (34), unusually strong temperature dependence of l3C chemical shifts (up to 0.077 ppm/K) was observed for long-lived cations 17a-c. The authors suggested that this resulted from a very low inversion barrier for the four-membered ring (Scheme 13). [Pg.139]

Fig. 3 a 1 3 syn-diaxial interactions established by OH2ni and OH5m with the vicinal OH3ni group are dependent on the ring 111 conformation, b Dependency exhibited by the intraresidue NOEs on temperature for the different sugar units. Selective NOEs obtained upon inversion of the three anomeric protons at 313 K (left) and 293 K (right)... [Pg.122]

Temperature-dependent lineshape changes were observed in an early study of the fluo-renyllithium(TMEDA) complex. A detailed study by lineshape analysis, which was also applied to the TMEDA complex of 2,3-benzofluorenyllithium(TMEDA) (Figure 29f, yielded barriers AG (298) of 44.4 and 41.9 kJmoD for the 180° ring flip in these systems, respectively . A second dynamic process, which was detected via the temperature dependence of, the spin-lattice relaxation time in the rotating frame, is characterized by barriers of 35.1 and 37.6 kJmoD, respectively, and may be ascribed to the ring inversion process. For the fluorenyl complex, a barrier AG (298) of 15.9 kJmoD for the methyl rotation in the TMEDA hgand was determined from temperature-dependent NMR spectra of the deuteriated system. [Pg.191]

The frequency vD at the edge of the Brillouin zone is thus equal to vsqD/2n. The Debye temperature 0D is defined as hvD/(kB). As shown below, 0D is an inverse measure for the vibrational mean-square amplitudes of the atoms in a crystal at a given temperature. [Pg.41]

Figure 4- Logarithms of the critical frequencies for absorptions A and B vs. the inverse of the absolute temperature for the four Na+ zeolites... Figure 4- Logarithms of the critical frequencies for absorptions A and B vs. the inverse of the absolute temperature for the four Na+ zeolites...
The barriers to inversion of l-aryl-2,2-dimethylaziridines have been investigated422 by means of low-temperature NMR. Calculation of the Avalues involves observation of the coalescence temperature for the protons of the methyl groups. The process is accelerated by n conjugation of the nitrogen lone pair in the transition state, and accordingly the... [Pg.63]


See other pages where Inversion temperatures for the is mentioned: [Pg.105]    [Pg.164]    [Pg.54]    [Pg.95]    [Pg.105]    [Pg.164]    [Pg.54]    [Pg.95]    [Pg.529]    [Pg.1128]    [Pg.35]    [Pg.32]    [Pg.283]    [Pg.102]    [Pg.1269]    [Pg.173]    [Pg.408]    [Pg.122]    [Pg.317]    [Pg.5]    [Pg.20]    [Pg.91]    [Pg.561]    [Pg.201]    [Pg.219]    [Pg.106]   


SEARCH



Inverse temperatures

Temperature inversions

© 2024 chempedia.info