Extraction equipment 808 INDEX

A retention index (RI) was used to allow comparison of compound retention data between columns of different equipment, e.g. GC and GC-MS. Straight chain hydrocarbons (alkanes) were assigned an index of 100 times the number of carbon atoms in the molecule. The RI s of all compounds within all the extracts were calculated by using the difference between the retention indices of the alkane eluting before and after that compound ... 

Figure 14 illustrates a comparison between solvent extraction yields predicted from adsorption analyses and actual raffinate yields in commercial solvent extraction plants. Few commercial yields have ever equaled those obtained by adsorption analyses and none has exceeded those values hence, curve A (45° angle) represents the ultimate in solvent extraction. Curve B represents solvent extraction in commercial equipment on stocks ranging in viscosity index from +25 to +110, and for viscosity index improvements ranging from 30 to 130. Extremely viscous stocks or those which require a very large viscosity index improvement have been observed to follow more closely lines C and D. 

Molecular weight and polydispersity of the acetone extracted fractions from thermally degraded samples were determined by SEC with a Jasco PU-1580 HPLC pump equipped with two Pigel mixed D columns (Polymer Laboratories UK) connected in series, and a Jasco 830RI refractive index detector. Sample elution was with THF at 1 ml/minute flow rate. The instrument was calibrated with standard polystyrene samples. 

The identification of individual classes of fatty acids has relied on the use of gas chromatography (GC), equipped with a flame ionization detector. Lipids are sapoiufled after extraction and the fatty acids converted to methyl esters. The fatty acid methyl esters (FAME) are separated using GC. The use of standards ahowed for the identification of individual species of fatty acids based on retention time. The method is quite sensitive and permits the quantification of fatty acid species. The mode of detection has been enhanced with the use of mass spectrometry (MS), which allows for the detection and quantification of unknowns, thus increasing the utility of these methods. The Lipid Library section on the gas chromatography of lipids http //www.lipidlibrary.co.uk/GCJipid/01 intro/index. htm) provides a comprehensive description of these methods. 

The SEC was equipped with a refractive index and photodiode array detector which were calibrated with poly(styrene) standards. Tetrahydrofuran was used as eluent and the data recorded by the photodiode array detector was evaluated at a wavelength of X = 257 nm, where poly(styrene) has an absorption maximum. The poly(styrene)-equivalent molecular weight of the copolymers determined by the SEC were found to be higher than the theoretical values. More accurate values were calculated using the SEC determined molecular weight of the styrenic macroinitiator together with the weight ratio of the two copolymer chains extracted from NMR data. 

Polymerization and analytical procedures Polymerization of propylene was conducted either in a 200 cm glass reactor or in a 100 cm stainless steel autoclave equipped with a magnetic stirrer. Polymerization was terminated by adding a dilute hydrochloric acid solution in methanol. The polymer produced was fractionated by extraction with boiling heptane for 10 h to determine the isotactic index (I.I.). The... 

Husky Index system provides a unique set-up for preform cooling. The machine is equipped with two or four sets of cores, which index each injection cycle. The preforms stay on the cores after being extracted from the cavity until the cores are in a position to engage the cavities again. Additional cooling is applied from the outside at other index positions. 

As demand for polyethylene has increased, there has been a continuous effort to improve catalyst activity. This was important to achieve high productivity at relatively short residence times. These properties have avoided the need to remove catalyst residues from the product It was also important for polypropylene to have a high isotactic index to ehminate the need for equipment for the extraction of atactic polymer. 

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