Branching at Different Temperatures

However, it is difficult to measure L0, while in most cases, Li and L, as defined in Fig. 20a, could be obtained easily when a subsidiary lamella grew to 

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Fig. 21 In-situ phase images of a BA-C10 film showing the lamellar branching at different temperatures a and b no branching at 80 °C c and d branching largely at the tips of lamellae when the temperature is quenched to 35 °C [64]. The time interval between a and b was about 106 min...

Fig. 26. a Specific optical rotations for the model building blocks for core 78, interior building block 79 and peripheral unit 80 of dendrimers of type 77 b calculated average optical rotations for the doubly branching dendrimers of Oth to 4th generation c measured optical rotations in CHC13 at different temperatures and concentrations [94]... 

Fig. 4.22 Arrhenius representation of the relaxation rates obtained from fitting stretched exponentials to the spectra of PB at Q=1.88 A" at different temperatures. The three symbols represent three different sets of experiments carried out in separate experimental runs. The solid line displays the viscosity time scale. The dashed line indicates the Arrhenius behaviour of the low-temperature branch. (Reprinted with permission from [188]. Copyright 1992 The American Physical Society)...

The reaction of branched-chain alkanes with hydrogen peroxide in Magic Acid-S02C1F solution has been carried out with various ratios of alkane and hydrogen peroxide and at different temperatures.602 Some of the results are summarized in Table 5.35. 

The morphology of a polyethylene blend (a homopolymer prepared from ethylene is a blend of species with different molar mass) after crystallisation is dependent on the blend morphology of the molten system before crystallisation and on the relative tendencies for the different molecular species to crystallise at different temperatures. The latter may lead to phase separation (segregation) of low molar mass species at a relatively fine scale within spherulites this is typical of linear polyethylene. Highly branched polyethylene may show segregation on a larger scale, so-called cellulation. Phase separation in the melt results in spherical domain structures on a large scale. 

Fig. 6.2-10 shows the absorbance of the second overtone stretching mode 3 3 of CO2 at 77 °C at densities varying from bottom to top, in steps of 0.1 g cm between 0.1 g cm and 1.2 g cm As the density increa.ses, the band contour with a pronounced R branch at 6980 cm is gradually transformed into an intense band with a low wavenumber shoulder. Closer inspection of the band shape at different temperatures and pressures reveals that, in addition to the food s) (00 0) transition, a Jl" ... 

Figure 6,8-12 Calculated Stokes (7-branch intensities for Nt at different temperatures.

Advances in the development of theoretical methods and computer construction are indispensable for the growing feasibility of ab initio calculations, but this alone does not guarantee a future widespread use of ab initio calculations by chemists in solving their problems. What is demanded by chemists is a high predictive power of theory in various branches of chemistry, A classical example of how the ab initio calculations should meet the needs of chemists was provided as early as in 1967 by dementi and Gayles " in their study on the complex NH. HCl, The calculation of the potential hypersurfaces and a detailed analysis of wave functions of both the complex and the dissociation components showed that NH Cl may exist in the gas phase. For the first time, the results of ab initio calculations were used for the evalua-tion of the equilibrium constant for a chemical reaction. Predicted equilibrium constants for the process NH2(g) + HCl(g) NH Cl(g) at different temperatures suggested the experimental conditions at which... 

Fig. 4.33. Measured CO oxidation rate on EBL-fabricated model catalysts with different support materials and particle sizes (a) The inlet gas mixture represented by the parameter (3 = Pco/ Pco + P02) has been scanned up/down at a constant temperature of 450 K, and the rate of CO2 production has been monitored during the gas scan in j3. This has been made for three different samples (a) 750-nm Pt/Si02 (blue), (b) 750-nm Pt/CeOj, (black), and (c) Pt/CeOj, sample (200mn, red, disintegrated particles). Results both from experiments (filled circles) and simulations solid lines) are shown. The arrows indicate which reaction rate branch that has been observed while scanning up/down in (3. A bistable region (hysteresis) is observed for all samples, (b) The bistability diagrams determined from a series of measurements as those shown in (a) at different temperatures (Pt/Si02, blue and open squares) Pt/CeOj, black hatch marks and crosses and the 200-nm Pt/CeOj, red hatched area and open squares). The observed differences can be traced back to a pronounced O-spillover effect on ceria. Note the logarithmic scale for the /3-value (from [29])...

The results discussed so far were obtained with polymers prepared at 55°C. We have now extended this investigation to U-PVC prepared at different temperatures. We report herein the thermal stability of U-PVC obtained in the temperature range 45-80 C and with the relative monomer pressure P/P ranging from 0.61 to 0.97. The structural characterization includes molecular weight by GPC/viscometry, branches by JC-NMR measurements on samples reduced with BUjSnH and internal double bonds by ozonolysis. 

Figure 5 compares 13C-NMR spectra of the polymers prepared at different temperatures. The main structure A becomes predominant at a low polymerization temperature as shown in Figure 5a, but the content of the other structures, particularly the branched cis ring B, increases at a higher temperature(Figure 5b). The fraction of structure A Increased from 66 to 89 X by lowering the polymerization temperature from 70 to 10°C at a fixed monomer concentration of 2.5 mol/1.

Deformation is obviously controlled by both the dislocation glide processes and the diffusive processes. The contribution from each process may be more, or less, at different temperatures. Hence, both branches of the phenomenological model will operate such that ... 

In this paper we report experimental results on the kinetics of the polyaddition reaction in the melt and in solution (diglyme) using two different catalysts, namely tetrabutyl ammonium hydroxide (TBAH) and benzyl triethyl ammonium chloride (BTAC) at different temperatures. By simultaneous measurements of a, and in two cases we have also evaluated the critical branching parameters. 

TABLE 4 The experimental and theoretical characteristics of PHE chain branching at different synthesis temperatures. 

Polymers are always polydisperse with a distribution in molar mass and often contain chain branches, either introduced specifically during synthesis or as a consequence of synthetic defects, and both these effects will influence the observed morphology. As we shall see later, copolymers are a special case however, the introduction of low levels of comonomers can lead to behaviour which is rather like that of random branched chains. Different molecular species crystallize in different stages indicating the thermodynamic control on the overall process, i.e. they are incorporated into the crystal structure at different temperatures and times. The intermediate and high molar mass component crystallizes early in the stacks of thick dominant crystals. Small pockets of rejected molten low molar mass material remain after crystallization... 

Leaf-like carbon sheets were obtained by the pyrolysis of dichloromethane and FcH in an autoclave at 300-600 °C [41]. The formation process was studied by observing the product evolution utilizing the real-time imaging capabilities of emission SEM. The study also reported the synthesis of different carbon nanostmctures by the chlorination of FcH at different temperature conditions the products included amorphous CNTs, open-ended branches, and carbon nanobags [41] (Fig. 33.13). 

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