Volume containers polystyrene

Figures 13.8 and 13.9 show the separation of polystyrene standards using a typical mixed-bed column and its calibration plot, respectively. The major advantages of using a large i.d. 10-mm column are low hack pressure and relatively short run times. As seen in Fig. 13.8,10 standards from toluene thru 8.4 X 10 MW can be resolved in a mere 21 min. Because of the large 10-mm i.d. columns, 1.5-ml/min flow rates give a linear velocity equivalent to that of only 0.9 ml/min using a 7.6-mm i.d. column. Also, the gel volume contained in one 10 mm i.d. X 500 mm column is 39.3 ml, whereas a 7.6 mm i.d. X 300 mm column contains only 13.6 ml of gel volume. This bulk volume factor, combined with the large pore volumes of gels, obtains essentially the same resolution as that obtained on three standard 7.6 X 300-mm columns in series, but in about one-half the usual time required using the smaller columns.

Indeed, much higher levels of conductance fluctuations were reported for electrolytes that contain polystyrene latex suspensions (21) or micellar colloids (22). Fluctuations were shown to depend on concentration, characteristic size, and the charge of colloid particles. For uncharged nonconductive spherical particles that occupy volume fraction F of the total sample volume... 

An important result of such studies was the realization that almost all commercially important polymer blends, blocks, and grafts clearly exhibit phase separation, and that each has its own characteristic fine structure. An example of a typical morphology for an impact-resistant plastic is shown in Figure 2.4. Although the polymer contains only 6% rubber, much of the volume of polystyrene is occluded (Wagner and Robeson, 1970). Those interested in the details of electron microscope construction and operation, as well as experimental techniques, should consult Hall (1966) or Kay (1965). 

The result of this equation describes the quality of the separation on the basis of an ideal size exclusion mechanism with a given pore volume distribution. The quality of the packing is deliberately excluded from this consideration. This parameter should be measured separately and judged by the plate number. The ASTM standard method for HPSEC of polystyrene (4) contains the following equation for resolution (R,) ... 

Polystyrene (PS) The volume of expanded polystyrene produced probably exceeds the volume production of all other plastics (excluding the polyurethanes) put together. At least half the weight of polystyrene produced is in the form of high impact polystyrene (HIPS)—a complex blend containing styrene-butadiene rubber or polybutadiene. 

I A 7.8 mm x 30 cm column containing the 104 A stationary phase above is used with methylbenzene as the mobile phase at a flow rate of 1.1 cm3 min 1. A sample of polystyrene standards dissolved in benzene is injected. The standards have molecular masses of 775 000, 442 000, 6200 and 2800. The void volume of the column is 6 cm3 and the interstitial volume is 5 cm3. 

The experiment will require a balance to determine the mass of a sample and possibly a pipet to measure a volume, from which a mass may be calculated using the density. A calorimeter, usually a polystyrene (Styrofoam) cup, is needed to contain the reaction. Finally, a thermometer is required. Tables of heat capacities or specific heats may be provided. 

To 5.3 g of 4-vinylpyridine is added to THE up to a volume of 50 ml 5 ml of this solution (containing 5 mmol 4-vinyl pyridine) are added in the same way to the above solution containing the "living" polystyrene, with vigorous agitation. After 15 min another 40 mmol of styrene are added, followed 15 min later by another 5 mmol of 4-vinylpyridine this operation is repeated once more. 15 min after the last addition of monomer the block copolymer is precipitated by dropping the solution into a mixture of 300 ml of diethyl ether and 300 ml of petroleum ether.The polymer is filtered, washed with ether,filtered again, and dried in vacuum at room temperature. 

A piece of the polymer (about 1 g) is placed in a 500 ml beaker, containing boiling water. At this temperature, the polystyrene softens and is foamed by the vaporizing pentane. The test piece is held below the surface of the water for 5 min with the aid of a piece of bent wire and is then removed.The foamed material obtained in this manner is dipped into a graduated cylinder, containing methanol, in order to determine its approximate volume it is also weighed after drying in a vacuum desiccator.The density is found to be below 0.1 g/cm (cf.,cork has a density of 0.2 g/cm ). 

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