Waxes structure

Elder, R.C., Ludwig, K, Cooper, J.N. and Eidsness, M.K (1985) EXAFS and WAXS structure determination for an antiarthritic drug, sodium gold(l) thiomalate. Journal of the American Chemical Society, 107, 5024—5026. 

This wax structure is the most common and consists primarily of linear n-paraffin molecules. The linearity of the wax molecules enables the wax to accumulate to form a uniform crystal lattice. The wax molecules actually stack together into a geometric form resembling a flat plate. 

Anonymous. (2006b). Waxes Structure, composition, occurrence and analysis [Online] http /www.lipidlibrary.co.uk/Lipids/waxes/ (posted 20-02-2006 verified 27-02-2006). 

An indication of this temperature may be obtained from the cloud point (ASTM D-2500,ASTM D-5771,ASTM D-5772,ASTM D-5773, IP 219) and pour point (ASTM D-97, IP 15). These test methods give, respectively, the temperature at which wax begins to crystallize out of the fuel and the temperature at which the wax structure has built up sufficiently to prevent the flow of oil. In these installations, a coarse filter is normally sited in the system near the tank outlet to remove large particles of extraneous matter a fine filter is positioned near the burner to protect the pump. 

The pour point of residual fuel oil may be influenced by the previous thermal history of the residual fuel oil and the fact that any loosely knit wax structure built up on cooling the fuel can, generally, be readily broken up by the application of a little pressure, thus allowing fuels to be pumped at temperatures below their pour point temperatures. The usefulness of the pour point test in relation to residual fuel oils is, therefore, open to question, and the tendency to regard it as the limiting temperature at which a fuel will flow can be misleading unless it is correlated with low-temperature viscosity. 

I. Rentschler, Significance of the wax structure in leaves for the sensitivity of plants to air pollutants. International Clean Air Congress, Third, Dusseldorf, Proc., pp. A139-A142, (1973). 

Each symbol stands for one experiment, while the symbol itself indicates the structure found, hi all cases, we can distinguish between the polymer and the wax structures that are observed under the respective contrast conditions. The structural areas are characterized by the following symbols C stands... 

Fig. 33 Structures diagram for the PEB-II/C24 system in decane the temperature dependence of the polymer and wax structure evolution as a function of wax content in solution. The capital letters denote the structural regimes delimited by lines and identified as C coil conformation, R rod structure, P platelets, B three-dimensional bulk aggregates. On the right side the different structures are sketched schematically. The data points indicate the temperature/wax concentration conditions, where SANS experiments were performed, while the symbols denote the structures (closed circles coils, closed triangles rods, closed squares platelets and closed diamonds three-dimensional bulk aggregates)...

Figure 34 shows the polymer wax structure diagram for PEB-7.5 and C24 wax in decane. Here the structure is more complex ... 

This inhibition of the VLCFAs was found to have secondary effects upon the quantity and quality of the epicuticular wax structure when electron micrographs (not shown here) of both barley and pea leaf controls were compared with treated samples. 

XI.1.1 The low-temperature flow properties of a waxy fuel oil depend on handling and ston conditions. Thus, they may not be truly indicated by pour point. The pour point test does not indicate what haqppens when an oil has a considerable head of pressure behind it, such as when gravitating from a storage tank or being pumped along a pipeline. Failure to flow at the pour point is normally attributed to the separation of wax from the fuel however, it can also be due to the effect of viscosity in the case of very viscous fuel oils. In addition pour points of residual fuels are influenced by the previous thermal history of the specimens. A loosely knit wax structure built up on cooling of Ae oil can be normally broken by the application of relatively little pressure. 

Fig. 12-5. Effect of wax structure on filtering rate in propane dewaxing (X120). Rates are gallons per square foot per hour. (Shell Oil Co.)...

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