Fractionation molecular weights

The first and second columns of Table 1.4 give the number of moles of polymer in six different molecular weight fractions. Calculate and for this polymer and evaluate a using both Eqs. (1.7) and (1.18). 

Since K represents the fraction of Vj at which a particular molecular weight fraction emerges from the column, and since In M cc in r we see that this... 

The lower molecular weight fractions from this process have been marketed by Montefluos under their trade name Galden. 

Oil Content. The production of petroleum waxes involves the removal of oil therefore, the oil content (actually the percentage of oil and low molecular weight fractions) is one indication of the quaUty of the wax. Oil content is deterrnined (ASTM D721) as that percentage of the wax soluble in methyl ethyl ketone at —31.7 C. 

Some skin sensitization to low molecular-weight DGEBPA resins (mol wt - 340) has been shown in animals and humans. Skin sensitization decreases with an increase in molecular weight but the presence of low molecular-weight fractions in the advanced resins may present a hazard to skin sensitization (43). 

Sodium poly(a-L-glutamate). It was washed with acetone, dried, dissolved in water and ppted with isopropanol at 5°. Impurities and low molecular weight fractions were removed by dialysis of the aqueous solution for 50h, followed by ultrafiltration through a filter impermeable to polymers of molecular weights greater the 10. The polymer was recovered by freeze-drying. [Mori et al. J Chem Soc, Faraday Trans I 2583 1978.]... 

Studies on the dimerization and hydrogenation of olefins with transition metal catalysts in acidic chloroaluminate(III) ionic liquids report the formation of higher molecular weight fractions consistent with cationic initiation [L7, 20, 27, 28]. These... 

Nonionic surfactants, including EO-PO block copolymers, may be readily separated from anionic surfactants by a simple batch ion exchange method [21] analytical separation of EO-PO copolymers from other nonionic surfactants is possible by thin-layer chromatography (TLC) [22,23] and paper chromatography [24], and EO-PO copolymers may themselves be separated into narrow molecular weight fractions on a preparative scale by gel permeation chromatography (GPC) [25]. 

These contaminates originate largely from the heavy (1,050-t- °F/ 566-t- °C), high-molecular weight fraction of the FCC feed. The quantity of these metals on the E-cat is determined by their levels in the feedstock and the catalyst addition rate. Essentially, all these metals in the feed are deposited on the catalyst. Most of the iron on the E-cat comes from metal scale from piping and from the fresh catalyst. 

Low molecular weight fractions can be detected by smelling the inside of almost any freshly made polyethylene container. The amount varies with the specific polyethylene resin and the type of processing that have been used. 

Table 1 gives yields and molecular weights for the total polymer and for the low and high molecular weight fractions (LMWF and HMWF). Since the resolution of GPC traces into LMWF and HMWF was estimated subjectively the molecular weights for these fractions are merely indicators of trends. 

In the low molecular weight fraction a relatively high content of the 3,4-linkages is formed, characteristic of the polymers produced in the presence of TMEDA. On this basis it was concluded that the unassociated polymers coordinated with TMEDA propagate more slowly than those unassociated and non-coordinated with the diamine, a conclusion concordant with the previously discussed findings of Fontanille84) and confirmed by Schue, 55> for lithium polyisoprene. 

Figure 4. Chromatogram on HW-40 S column of the low molecular weight fraction (Fraction 3) from the HW-55 S column chromatography of the EPG-digested alkali extract.

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