Chain length component

SiUMA chain length, component ratios, and a component absolute percentage. 

Note that, again, three different types of variables were combined chain length, component ratio, and absolute component level. Thus, a "standard" constrained mixture design was not appropriate. In this case a full factorial, central composite design was used, with a total of 20 data points. The star points were... 

Materials. Sodium dodecylsulfate (SDS) and fully deuterated sodium dodecylsulfate (SDS-d ) were obtained from Sigma and Cambridge Isotope Laboratories respectively, and used as received. The cationic surfactants, dodecyltrimethylammonium chloride (DTAC), dodecyltrimethylammonium bromide (DTAB), and didodecyldimethylammonium bromide (DDAB) were purchased from Eastman Kodak, and purified by repeated recrystallization from an ethanol/acetone solvent pair. Even so, a small amount of surface active impurity was observed in surface tension plots for DTAC. The tetradecyldimethylamine oxide (C14AO) was a commercial sample (Ammonyx MO) obtained from Stepan (Control No. 533-30027). This sample is primarily C14AO, but also contains other chain length components. Sodium chloride (NaCl) was obtained from EM Science and used as received. Water was purified by a three stage Bamstead water purification system. 

At a certain chain length (components of at least 6-8 C-atoms) (Dorset, 1990) such amphiphiles tend to self-organisation. At temperatures above 80-90 C the substances can be homogeneously melted below 90 C a phase separation arises, i.e. the hydrocarbon residues crystallise in the proximity of hydrocarbon residues whilst the perfluoroalkyl residues only crystalhse in the proximity of other perfluoroalkyl residues. During the crystallisation of such compounds in air the... 

This chapter provides a formal kinetic description of multicenter chain reactions, where in the rate-limiting steps several carrier chains participate simultaneously. Internal system relations in a multicenter chain reaction are discriminated by the chain length, components These quantities are considered as a response of the rate of formation of some reaction product, due to a small change in the rate of origination of certain chain carrier. The issues of organic coimection of value quantities with characteristic quantities of multicenter chain reactions ate discnssed. 

The fact that in a multicentered approach the chain process is described by species chains generated by different active centers is the distinguishing feature, as compared to the one-centered approach. This statement needs to be explained further. Thus, the product Pi is formed by the chains initiated by different active centers R,. The key parameter discriminating the chain ways, which result in the formation of the product is a chain length component vj. 

The chain length components Vj specifies the value for the step of the active reaction... 

Obviously, under conditions of the multiroute nature of the chain process, the product P, may appear in different chain links. Thus, for a chain reaction with three chain carriers, the corresponding links of the chain length component y for the P, product formation, initiated by the active center R, are illustrated in Figure 5.2. 

Now let us derive the analytie dependence for the rate of the P product formation and the chain length component vj, on the quantitative characteristics of individual steps (r°, ku, ki), for the multicentered non-branching chain process [9]. In accordance with the reaction scheme illustrated in Figure 5.1 the rates of the chain carrier formation are ... 

Thus, the chain length component is quite a meaningful quantity from the kinetic viewpoint, which is determined also by the alternative method based on a stochastic interpretation [11]. 

Simultaneously it follows from the condition (5.11) that the chain length component initiated by the R chain carrier at the minimmn exceeds one of those initiated by the arbitrary chain carrier... 

Nevertheless let us highlight two aspects specific for the chain reactions. Firstly, the value analysis method of kinetic models enables to reveal and examine the critical phenomena inherent to branching chain reactions. The results of such investigations are presented in the next paragraph. Secondly, the parametric corollaries (of the value method impart a new meaning to the introduced important feature of chain reactions, the chain length component v/. 

These products can be determined by titration. Although they are cationic at low pH, then-ion pairs with anionic surfactants are not sufficiently insoluble that the regular anionic/ cationic titration method can be used. This is especially true of the lower chain length components of, for example, a cocoamidoalkylbetaine. A better system is to use tetra-phenylborate ion as titrant with the electrode system typically chosen for the titration of nonionics (18). 

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