Oxyethylation, degree

The same applies to the oxyethylation of FAME. Thus, the reaction depends on the rate of EO transport to the liquid phase. The delivered EO is immediately consumed in successive parallel reactions giving products with various numbers of oxyethylene groups. The rate constants of the first, second, third, and nth reaction steps are denoted by Kq, k-y, and respectively. However, the contribution of the reaction depends on the process temperature and degree of oxyethylation. An increase in temperature enhances the role of diffusion, whereas an increase in oxyethylation degree has an opposite effect caused by an increased concentration of EO dissolved in the liquid phase. All this means that the computed constants cannot be considered as typical kinetic constants but only as relative estimates of consecutive reaction steps. 

Evaluated Ratios of Successive Pseudo-Rate Constants kjk (Average Oxyethylation Degree [n])... 

FIGURE 17.6 Changes in surface tension of 1 wt% oxyethylated alcohol solutions as a function of (a) oxyethylation degree and (b) length and nature of the alkyl chain. 

Except for the previously noted solution of oxyethylated oleyl alcohol (CigHjjEOio), no pronounced effect of the increase in alkyl chain length or oxyethylation degree on the resistance to motion can be observed. The measured values are comparable within the margin of error. 

The dependence of wear-scar diameter as a function of concentration and the type of additive is presented in fig. 17.19. The wear-scar diameter for the majority of solutions of oxyethylated alcohols and their concentrations decreases up to twofold relative to water (1.8 mm). Only for 0.1 wt% solutions are the wear-scar values greater than 1, with a maximum value of 1.6 (0.1 wt% solution of CJ2H25EO23). For concentrations equal to and above 0.5 wt%, the measured d values range from 0.9 to 1.1. Even oxyethylated oleyl alcohols do not exhibit any deviations from this. The effect of oxyethylation degree and the type of alkyl chain is analyzed on the basis of the results in fig. 17.20. There is no pronounced effect of the structure of the compound on wear under constant loading conditions. 

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