Structure and temperature

Table 6. Typical Structures and Temperature Ranges for Synthetic Oils ...

The effects of structure and temperature on the densities of a homologous series of esters were investigated. In all, five different series of esters were considered. 

The ANN was able to assimilate the cause-effect relationship of the density of the ester, its structure and temperature. The training and testing results are shown in Fig. 10-14 for individual ester series. The network with the proposed training routine converged in less than 100 iterations for all the esters. 

Cotton, F. A., Frenz, B. A., Deganello, G. Shaver, A. (1973) Fluxional organometallic molecules. XXXIV. The structure and temperature-dependent NMR spectrum of cis-(l,2,6-trihap/o- 3,4,5-fri/iapto-bicyclo[6.2.0]deca-l,3,5-lriene)hexacarbonyldi iron(Fe—Fe)," J. Organomet. Chem. 50,227-240. 

Little is known about the variation of the critical stress ", with structure and temperature. For the polyethylene discussed abovedecreased from 620 psi at 22X to 39general trend with all polymers. Turner (84) found that the value of (r(. for polyethylenes increased by a factor of about 5 in going from a polymer with a density of 0.920 to a highly crystalline one with a density of 0.980. Reid (80,81) has suggested that for rigid amorphous polymers. ", should be proportional t° (Tt - T) For brittle polymers, the value of ", may be related to the onset of crazing. 

The rate constant of their decomposition depends on the peroxyl radical structure and temperature (see Table 7.5). 

The viscosity of some polymers at constant temperature is essentially Newtonian over a wide shear rate range. At low enough shear rates all polymers approach a Newtonian response that is, the shear stress is essentially proportional to the shear rate, and the linear slope is the viscosity. Generally, the deviation of the viscosity response to a pseudoplastic is a function of molecular weight, molecular weight distribution, polymer structure, and temperature. A model was developed by Adams and Campbell [18] that predicts the non-Newtonian shear viscosity behavior for linear polymers using four parameters. The Adams-Campbell model is as follows ... 

The combustion wave of an HMX composite propellant consists of successive re-achon zones the condensed-phase reachon zone, a first-stage reaction zone, a second-stage reaction zone, and the luminous flame zone. The combustion wave structure and temperature distribution for an HMX propellant are shown in Fig. 7.47. In the condensed-phase reaction zone, HMX particles melt together with the polymeric binder HTPE and form an energetic liquid mixture that covers the burning surface of the propellant. In the first-stage reaction zone, a rapid exother-... 

We have prepared a number of acylium ions on metal halide powders and measured the principal components of their chemical shift tensors (43-45). Most of these cations have isotropic l3C shifts of 154 1 ppm. Often insensitivity to substituents results from opposite and offsetting variations in the principal components. The acetylium ion has an axially symmetric chemical shift tensor because of its C3 rotation axis. When the symmetry is reduced from C3v to C2v or lower, a nonzero 27 value may be observed. The sensitivity of chemical shift tensors to symmetry is a powerful means of probing molecular structure and temperature-dependent molecular dynamics. Multiple orders of spinning sidebands may offend those who seek solution-like NMR spectra of solids, but discarding most of the information inherent in the chemical shift is a considerable concession to aesthetics. 

The utility of the simple fluid theory lies in the plausibility and generality erf its assumptions about how materials behave and in the exactness with which its conclusions are worked out. In particular, one is inclined to believe, as a working hypothesis and in the absence of contradictory evidence, that the theory is general enough to encompass the behavior of homogeneous polymeric liquids. On this basis the role of molecular theories is a complementary one, to provide forms for the material functions and to account for their systematic change with molecular structure and temperature. 

Often, it is important to know not only the property itself at a standard temperature but also its temperature dependence. Temperature functions are available for a wealth of fluid compounds, such as solvents. However, these functions are compound specific. For limited sets of compounds, functions have been developed that describe properties as a function of both molecular structure and temperature (Section 1.9). 

In certain cases structure-temperature-property relationships have been developed that allow the estimation of a property as a function of both structure and temperature but do not require any additional compound properties. The general model is... 

V. T. Pham and R. S. Phillips, Effects of substrate structure and temperature on the stereospedfidty of secondary alcohol dehydrogenase from Thermoanaerobacter ethanolicus,]. Am. Chem. Soc. 1990, 112, 3629-3632. 

Trice, R.W., and Halloran, J.W. (1999), Influence of micro structure and temperature on the fracture energy of silicon nitride/boron nitride fibrous monolithic ceramics , J. Am. Ceram. Soc., 82(9) 2502-2508. 

The influence of structure and temperature upon oxidation selectivity on a methyl group was investigated. A mechanism has been proposed.158 7,7-Dimethyl-2-methylenenorbornan-l-ol undergoes an anomalous ozonolysis to yield a mixture of a rearranged /i-hydroxy ketone and a fragmented carboxylic acid.159... 

Kimmerle B, Baiker A, Grunwaldt JD. Oscillatory behaviour of catalytic properties, structure and temperature during the catalytic partial oxidation of methane on Pd/Al203. Phys Chem Chem Phys. 2010 12 2288. 

Hannemann S, Grunwaldt JD, Kimmerle B, Baiker A, Boye P, Schroer C. Axial changes of catalyst structure and temperature in a fixed-bed microreactor during noble metal catalysed partial oxidation of methane. Top Catal. 2009 52 1360. 

Results of hydrogen retention, as a function of incident ion energy, ion fluence, graphite structure and temperature, are presented, and their implication for ITER is discussed. During H+ irradiation of graphite, once the near surface is saturated, essentially all of the incident H+ is re-emitted from the surface -except for the small fraction that diffuses into the bulk - in the form of H2 molecules, H° atoms, and hydrocarbons. The relative amounts of these species depend on temperature. During post-irradiation thermal desorption spectroscopy, again FR, CH4, and H° are released. 

The ionic liquids are dense systems, with the density exhibiting well-defined temperature dependencies. Table 5.2 shows the density of the ionic liquids in a range of temperatures. The density decreases linearly with the temperature increase, regardless of the ionic liquid strucmres. Based on the density data and the molecular weight, molar concentration of each ionic liquid has also been calculated and listed in Table 5.2. Molar concentrations of the ionic liquids are high, and they change with structures and temperature. 

In fact, all materials are magnetic to some extent, with their response depending on their atomic structure and temperature. They may be conveniently classified in... 

Townsend A. R., Vitousek P. M., Desmarais D. J., and Tharpe A. (1997) Soil carbon pool structure and temperature sensitivity inferred using CO-2 and 13CO-2 incubation fluxes from five Hawaiian soils. Biogeochemistry (Dordrecht) 38(1), 1-17. 

Unfortunately, there is no report on the detailed physical characterization of these polymers. Such information as unidirectional twist angle and form optical rotation, as well as their dependence on chemical structures and temperature, can be very useful in further understanding the molecular orientations of the polymers in the cholesteric phase. In contrast, a number of studies have been made on the physical-chemical properties of cholesteric lyotropic polymer systems, especially polypeptides. 

Figure 17. The molecular structure and temperature dependence of the "Fe Mdssbauer parameters (IS and QS) and half-width of the absorption line (h) and some parameters of the nonprimitive unit cell of the FeNx i(BHd)2 crystal [67],...

The propagation step in ionic polymerizations is considerably more comphcated than in free radical polymerization (5). In addition to monomer structure and temperature, solvent and counter ion type are of importance. The separation between the counter ion and the active polymer chain end is the primary rate determining factor it can be represented schematically as an equilibrium between four species of different level of separation ... 

The ease of rotation of chain segments has a great influence on the properties of a polymer structure. As previously discussed, this is a function of polymer structure and temperature. The glass transition temperature of a polymer is that temperature at which backbone segments begin to rotate. An ideal noncrystalline polymer is a glass below the transition temperature and a non-Newtonian viscous liquid at temperatures above Tg. Thus, normally, plastics have Tg values above the use temperature, while elastomers have Tg values below the use temperature. 

Davis SM, Zaera F, Somorjai GA (1982) Surface structure and temperature dependence of light-alkane skeletal rearrangement reactions catalyzed over platinum single-crystal surfaces. J Am Chem Soc 104 7453... 

The value of Z is sensitively dependent upon the material species, composition, dopant level, structure and temperature. 

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