Chain-length distribution

Because the higher alcohols are made by a number of processes and from different raw materials, analytical procedures are designed to yield three kinds of information the carbon chain length distribution, or combining weight, of the alcohols present the purity of the material and the presence of minor impurities and contaminants that would interfere with subsequent use of the product. Analytical methods and characterization of alcohols have been summarized (13). 

Palm oil[8002-75-3] is derived from the fleshy fmit of the palm tree rather than the nut as with palm kernel oil. Palm oil has a longer chain length distribution than palm kernel oil and provides properties and compositions more similar to tallow than to other vegetable oils (see Table 1). 

L. Schafer. Chain length distribution in a model of equlilibrium polymerization. Phys Rev B 46 6061-6070,1992. 

Therefore the a(1 6) branching linkages were hydrolized selectively. The resulting constituting chain-length distribution was determined on a semipreparative Sephacryl S-200/S-400/S-500/S-1000 (12 -I- 55 -I- 66 -I- 135 X 1.6 cm)... 

It is also useful to define the moments of the chain length distribution. The yth... 

A given chain will undergo i-1 propagation steps (each with probability 0) before terminating (with probability 1-0). Thus, if termination is wholly by chain transfer or disproportionation, the chain length distribution is given by cq. 17 (Figure 5.1) ... 

In conventional radical polymerization, the chain length distribution of propagating species is broad and new short chains are formed continually by initiation. As has been stated above, the population balance means that, termination, most frequently, involves the reaction of a shorter, more mobile, chain with a longer, less mobile, chain. In living radical polymerizations, the chain lengths of most propagating species are similar (i.e. i j) and increase with conversion. Ideally, in ATRP and NMP no new chains are fonned. In practice,... 

It has been shown that equivalent information can be obtained by analysis of logfnumbcr chain length distribution) plots (the log CLD method)."4" 7 For the case where termination is wholly by disproportionation or chain transfer, it is possible to show that (eq. 6) applies ... 

While it is, in principle, desirable to take the limiting slope of the log CLD plot, in practice the limiting slopes are very susceptible to experimental noise and baseline choice issues. Moad and Moad24 have shown that very little error is introduced by systematically taking the slope over the top 10% or the top 20% of the chain length distribution. The values for the slopes will overestimate ln(0). However, because the discrepancy is systematic, the Mayo" analysis still provides a good estimate for C ( 6% error for the example in Figure 6.1). 

The T containing sequences can be evaluated using expressions analogous to those described in Section 7.3.2.1 to provide the chain end compositions and the chain length distribution. 

Chain length distribution (mean carbon chain length 15) [Pg.149]

Another chromatographic method is pyrolysis/gas-liquid chromatography. The sample is mixed with P205 and heated to 400°C. This technique yields the chain length distribution of the fatty acids initially used [107],... 

The physical detergency and biodegradation characteristics of primary alcohols are affected by the carbon chain length distribution. Therefore each new supply may require testing to determine whether the desired properties in the chosen application can be achieved. Examples of guideline specifications are presented in Table 10. 

Principle. The content of 1,4-dioxane in ether sulfates is determined by headspace gas chromatography according to the standard additions method. The method is suitable for all ether sulfates and gives reliable results independent of chain length distribution and water content. 

Wj. weight chain length distribution of the primary molecules,... 

Fig. 5. Variation in the chain-length distribution in M. citrifolia suspensions during a typical experimental jet run [130]...

Schlaad H, Smarsly B, Losik M (2004) The role of chain-length distribution in the formation of solid-state structures of polypeptide-based rod-coil block copolymers. Macromolecules 37 2210-2214... 

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