Branch determinate

Yu, L. -P, Rollangs, J. E. (1987). Low-angle laser light scattering-aqueous size exclusion chromatography of polysaccharides molecular weight distribution and polymer branching determination. Journal of Applied Polymer Science, 33, 1909-1921. 

Regioselectivity linear to branched, determined by GC analysis and or H NMR spectroscopy. 

Long-Chain Polymer Branching Determination by GPC-SEC Andre M. Striegel... 

Naming branched-chain alkenes When naming branched-chain alkenes, follow the lUPAC rules for naming branched-chain alkanes—with two differences. First, in alkenes the parent chain is always the longest chain that contains the double bond, whether it is the longest chain of carbon atoms or not. Second, the position of the double bond, not the branches, determines how the chain is numbered. Note that there are two 4-carbon chains in the molecule shown below, but only the one with the double bond is used as a basis for naming. This branched-chain alkene is 2-methylbutene. 

In the case of doped semiconductors, the assumption < no or 6n < po is almost impossible to fulfill for minority carriers under experimental conditions. An increase of the light intensity then leads to a decrease of the surface recombination velocity along the branch determined by the minority carrier density (for details see ref. [5]). 

The crystallinity of the samples rather than the degree of branching determines the relative importance of the a and of the j3 and y peaks. The a traps exist in the crystalline regions of polyethylene, the y traps in the amorphous regions and the j3 traps possibly in or around the surfaces of the crystallites. 

The principal factors affecting orientation in acetate decompositions have been adequately summarised by DePuy and King Essentially three influences were recognised, these being termed statistical, steric and thermodynamic effects. Statistical control is observed in pyrolysis of simple aliphatic esters which under the elevated reaction temperatures experience little resistance to conformational rotation and the number of beta hydrogen atoms in each branch determines the direction of elimination (147)= 37o distortion in statistical control is imposed by the steric influence of a t-butyl substituent (148), and is also illustrated by the predominance of trans- over m-olefin formation (148, 149) due to eclipsing effects . The latter example, however, may also arise from thermodynamic influences which are more certainly demonstrated by preferential elimination towards a phenyl rather than an alkyl substituent (150) . The influence of substituents on olefin stability rather than beta hydrogen acidity seems more critical as elimination occurs more often towards a p-methoxyphenyl rather than a phenyl substituent (151... 

From sets of spectra such as those shown in Fig. 3 and uptake curves displayed by Fig. 8 not only isotherms and isosteres could be derived, using the respective plateaux for the temperatures and pressures indicated, but also from the ascending branches (measured via FTIR after an upward pressure jump) or the descending branches (determined after a downward pressure jump) the kinetics of adsorption and desorption into zeolitic pores could be derived. These processes were assumed to be diffusion controlled. Their evaluation required a fit of the appropriate solution of Tick s second law as provided by Crank [39] to the experimentally measured uptake (or removal) points, which are indicated in Fig. 6 by filled crosses for the case of ethylbenzene uptake. 

Regioselectivity linear to branched determined at complete conversion after 20 h... 

Crystalline materials reveal a variety of patterns when they occur at different conditions. Pattern formation is the subject of significant fimdamental and practical interest, and receives broad attention across various areas from materials science, biology, health, mineralogy, etc. [42-45]. This is because these patterns, which are most likely to capture hquid between the branches, determine the rheological and other physical properties of the system. 

The extent of chain branching determines the physical properties of the resulting polymer. For example, a flexible plastic squeeze bottle and its relatively inflexible cap are both made from polyethylene, but the former has extensive branching while the latter has relatively little. These processes will be discussed in more detail in Chapter 27, and we will see that the extent of branching can be controlled with specialized catalysts, although a small amount of chain branching is generally unavoidable. 

Some of the characteristics of the different PF types discussed previously are presented in Table 2.1. The type of chains and the degree of branching determine the ultimate properties of a polymer. The properties can be tailored by adjusting the polymerisation method or the reaction conditions to favour differing degrees and forms of branching along the backbone. 

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