Polystyrene linear, rate

The cross sectional area of the equipment was 0.14 m and the linear rate of flow of air during the test procedure was 72 m/min, thus, the cross section was swept by 10 m of air per minute. The minimum amount of the calculated gas mixture for providing ignition was 0.33 m min for wood, 0.111 m /min for polystyrene, 0.272 m /min for poly(propylene oxide), and 0.258 m min for rigid polyurethane foam. 

FIGURE 10.8 Analysis of sulfonated polystyrenes on SynChropak GPC Linear. Column 250 X 4.6 mm i.d. Flow rate 0.5 ml/min. Mobile phase 0.1 M sodium sulfate, pH 7. (From MICRA Scientific, Inc., with permission.)... 

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.

When water (a Newtonian liquid) is in an open-ended pipe, pressure can be applied to move it. Doubling the water pressure doubles the flow rate of the water. Water does not have a shear-thinning action. However, in a similar situation but using a plastic melt (a non-Newtonian liquid), if the pressure is doubled the melt flow may increase from 2 to 15 times, depending on the plastic used. As an example, linear low-density polyethylene (LLDPE), with a low shear-thinning action, experiences a low rate increase, which explains why it can cause more processing problems than other PEs. The higher-flow melts include polyvinyl chloride (PVC) and polystyrene (PS). 

This paper extends previous studies on the control of a polystyrene reactor by including (1) a dynamic lag on the manipulated flow rate to improve dynamic decoupling, and (2) pole placement via state variable feedback to improve overall response time. Included from the previous work are optimal allocation of resources and steady state decoupling. Simulations on the non-linear reactor model show that response times can be reduced by a factor of 6 and that for step changes in desired values the dynamic decoupling is very satisfactory. 

Novolac molecular weights were measured in THF at 35°C by high pressure size exclusion chromatography using a Waters Model 510 pump (flow rate=1.0 ml/min), 401 differential viscometer detector and a set of Dupont PSM 60 silanized columns. A universal calibration curve was obtained with a kit of 10 narrow molecular weight distribution, linear polystyrene standards from Toya Soda Company. Data acquisition and analysis were performed on an AT T 6312 computer using ASYST Unical 3.02 software supplied with the Viscotek instrument. 

Fig. 14 a, b. Effect of gradient steepness on the very fast separation of polystyrene standards in a molded monolithic poly(styrene-co-divinylbenzene) column (Reprinted with permission from [121]. Copyright 1996 Elsevier). Conditions column, 50 mm x8 mm i.d., mobile phase, linear gradient from 100% methanol to 100% tetrahydrofuran within a 1 min b 12 s, flow rate, 20 ml/min, peaks represent polystyrene standards with molecular weights of 9200,34,000 and 980,000 (order of elution), 3 mg/ml of each standard in tetrahydrofuran, injection volume 20 pi, UV detection, 254 nm... 

Figure 3.15 Chromatogram of fibre-type proteins on polystyrene gels having different pore sizes. Column A, PLRP-S 300 A, 15 cm x 4.6 mm i.d. B, PLRP-S 1000 A (polystyrene gel), 15 cm x 4.6 mm i.d. eluent, 15 min linear gradient from 20% of 0.25% trifluoroacetic acid to 60% of 0.25% trifluoro-acetic acid in 95% aqueous acetonitrile flow rate, 1.0 ml min-1 detection, UV220 nm. Peaks 1, collagen (Mr 120 000) and 2, fibrinogen (Mr 340 000). (Reproduced by permission from Polymer Laboratories data)...

The direct quaternization of chloromethylated polystyrenes by tertiary amines or phosphines represents the easiest way to obtain polymer-supported quaternary onium salt (12,13). A lipophilic character of quaternary cation and a topology allowing sufficient cation-anion separation also play an important role (35,36). A linear spacer chain (of about 10 carbon atoms) between the catalytic site and the polymer backbone substantially increases the reaction rates. The loading of quaternary onium groups also affects catalytic efficiency, the influence being different for directly bonded and spaced groups, e.g. 10 and 11, respectively (37). 

This work was done with a Waters Model 244 liquid chromatograph having two Du Pont Blmodal IIS columns (29,000 plates/meter) and a Linear dual-pen recorder. Also used was a Waters Model 440 UV absorbance detector. Samples were run at 0.1% (w/v) using an Injection volume of 25-pL and a flow rate of 1 mL/mln. The system was calibrated with polystyrene standards from Pressure Chemical Co. according to the universal callbaratlon procedure. Data collection and computation were done with an Intel 80/30 microprocessor. 

The calibration standards included sodium form polystyrene sulfonates obtained from Pressure Chemical Co., Pittsburgh, Pa., and sodium toluene sulfonate. Measurements were taken at 0.5 to I.Oml/mln flow rates. The logarithm of the molecular weight of the standards was linear it suggests a framework for approaching an interpretion of the structure of the scission products. This application of size exclusion chromatography measurements must be viewed as a first approximation because of the unmeasured differences between the chromatographic behavior of the linear standards and the expected branched structure of the scission products. 

When gas concentrations are calculated for these polymers, the combined effects of low diffusivity and higher gas generation rate result in the conclusion that gas diffusion out of the polymer has a small effect on the gas concentration in the polymer for samples in the 0.033 to 0.100-inch thickness range. As a further result, the calculated gas concentration for these samples increases linearly with time in the manner observed for the thicker polystyrene samples (Figure 19). The calculated gas concentration will start to approach an equilibrium concentration at some greater time, when the rate of gas diffusion out equals the rate of gas generation, but this point is evidently not reached within the time scale of the present experiments. 

Wyman and co-workers (120) studied the viscosity of narrow MWD linear and 4-armed star polystyrenes as a function of shear rate. At low shear rates, the star polymers (of MW 204000 and 430000) had low-shear viscosities much lower than linear ones of the same MW it may be remarked that the branch length... 

Graessley s theory, though satisfactory for linear polymers, has not yet been shown to apply to branched polymers. Fujimoto and co-workers (65) attempted to apply it to comb-shaped polystyrenes, but obtained only poor agreement with experiment. They attributed this to the failure of the assumption that the state of entanglement is the same in branched polymers as in linear ones. It is not surprising that this theory fails, for (in common with earlier theories) it predicts that the zero shear-rate viscosity of all branched polymers will be lower than that of linear ones, contrary to experiment. 

Anionic polystyrene Sill seems to be a suitable polymer for this type of investigation. Some solution properties of this polymer have already been discussed in the previous chapter. Fig. 2.4 gives some properties of the melt of this polymer at a measurement temperature of 196° C (56). In this figure the doubled extinction angle 2% as a function of shear rate q (open circles) is compared with the loss angle d as a function of angular frequency (closed circles). In accordance with eq. (2.22) the initial slopes of these curves coincide. This coincidence, however, appears to persist even into the non-linear part of the functions. Such a persistence... 

Fig. 5.9. Comparison of extinction angle curves of high molecular weight fractions of polystyrene and cellulose tricarbanilate, using linear scales and reduced shear rate For data on polystyrene Taps. No. 5 and solvents see Table 3.2. (n) Taps. No. 5 in methyl (4-bromo-phenyl carbinol) at 18° C (theta-temperature), (V) the same at 50° C, (o) Taps. No. 5 in monobromo benzene at 25° C, ( ) cellulose tricarbanilate M = 720,000 in benzophenone at 55° C (jy = 4.70 cps) and (a) at...

The linear increase of S with n was established experimentally with polystyrene oligomers 3 4). Of course, Eq. (6) is bound to the same decline at high degree of polymerization as Martin s rule but, at any rate, high polymers have high S values. They are in general so large that elution is restricted to an extremely narrow interval of eluent composition, vide supra. 

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