Pressure Chemical Company

Potassium Hydride. Potassium hydride [7693-26-7] KH, made from reaction of molten potassium metal with hydrogen at ca 200°C, is suppHed in an oil dispersion. Pressure Chemical Company (U.S.) is a principal suppHer. KH is much more effective than NaH or LiH for enolization reactions (63,64). Use of KH as a base and nucleophile has been reviewed (65). 

PRENTOX , pyrethrum pesticides, 111 PRESPERSION PAB , zinc oxide, 111 Pressure Chemical Company, 245 PREVAIL , cypemietlu-in, 111 Priborlabs, 197... 

Polystyrene standards of known MW used in this study (Pressure Chemical Company and National Bureau of Standards) were narrow MWD, with MW values ranging from 4000 to 1.8 million, except for one broad standard,... 

The polystyrene data were collected from a steady state, continuous, well-mixed reactor. The initiator was n-butylli-thlum for data of Figure 2 and was azobisisobutylnitrile for data of Figure 3. Toluene was used as a solvent. The former polymerizatl n y ields an exponential population density distribution ( ), M /M = 1.5 the latter yields a molar distribution defined as th product of degree of polymerization and an exponential ( ), M /M = 2.0. Standards utilized in calibration of both instrumen s ftere polystyrene supplied by Pressure Chemical Company. 

The NMR measurements were performed on systems composed of ca. 25 wt. % samples of aPS (M = 6.6x 10 g/mol, PD = 1.1, Pressure Chemical Company) in either reagent grade toluene (Aldrich) or toluene-d0 (Aldrich). The protonated solvent was used for the diffusion measurements and the deuterated solvent for the relaxation studies. At this concentration, the Tg j for the system was determined to be about -65 °C (i). The NMR spectra were run on a JEOL FX-90Q NMR spectrometer operating at 90 and 14 MHz for protons and deuterons, respectively. The T and T2 measurements were made with the standard inversion-recovery and spin-echo (CPMG) sequences, respectively. 

Viscotek Corporation, 1030 Russell Drive. Porter, TX 77365 Modchrom, Inc., 8666 Tyler Boulevard, Mentor, OH 44060 Pressure Chemical Company, 3419 Smallman, Pittsbui h, PA 15201... 

ModChrom, Inc., 104,119 Monsanto Company, 263 Nanjing University, 281 Pressure Chemical Company, 119 State University of New York, 240 Texas A M University, 183 University of Akron, 155 University of South Florida, 220 University of Toronto, 59,202 Viscotek Corporation, 119... 

GPC performance was tested using polystyrene standards dissolved in the same solvent. The polystyrene standards (average molecular weights 300,000, 100,000, 50,000, 35,000, 17,500, 4,000, 2,000 with polydispersity < 1.06) were obtained from the Pressure Chemical Company. 

Figure 5.12 shows JeR obtained by different investigators on a single sample of narrow distribution polystyrene [sample 6a, Mw=860.000, Mw/M = 1.05 (174), polymerized anionically by the Pressure Chemical Company, Pittsburgh, Pennsylvania]. A number of different solvents, temperatures, and methods are represented (175-182). The values rise from below 0.4 at low concentrations, pass through a broad maximum which somewhat exceeds 0.4, then decrease again at high concentrations. Data from dynamic moduli, normal stress measurements, and... 

Table 5.4. Values of JeR for narrow distribution polystyrenes from Pressure Chemical Company, Pittsburgh, Pa., USA JeR = J RT/M ...

Phenylphosphine is available from Pressure Chemical Company and Strem Chemicals Inc. It is best stored in a dry box under nitrogen. The compound is extremely air sensitive and malodorous. The container should be handled in the hood while wearing rubber gloves. Satisfactory preparations of phenylphosphine have been described in the literature.2... 

Chromium hexacarbonyl was obtained by the checkers from Pressure Chemical Company, Pittsburgh, PA, and used without purification. It can be weighed 1n air as it is relatively non-volatile and air-stable. The usual precautions appropriate for a potentially toxic metal carbonyl should be employed, but the low volatility makes handling relatively easy. 

Tungsten hexachloride, purchased from Pressure Chemical Company, was used without further purification. The dark blue-black crystals were pulverized in a dry box or glove bag under a nitrogen atmosphere prior to use. Upon exposure to air or moisture yellow or orange oxides form. Slight contamination from these products does not interfere with the deoxygenation. 

Tungsten hexachloride, WCl. Mol. wt. 396.66. Suppliers Alfa Inoiganics, Pressure Chemical Company, ROC/RIC. 

Materials. Narrow PS standards were obtained from Pressure Chemical Company (Pittsburgh, PA). A broad PS standard (MW = 250,000) was obtained from American Polymer Standards Corp. (Mentor, OH). The PMMA materials were Perspex CQ UV obtained from Imperial Chemical Industries (Wilmington, DE) and UV 52E obtained from Pharmacia Ophthalmics Inc.(Monrovia, CA). High-performance liquid chromatography-grade THF from JT Baker Inc. (Phillipsburg, NJ) was used as a carrier for all ThFFF and SEC experiments. The polymer solutions had concentrations of 0.2% (wt/vol). 

The SEC columns were calibrated using narrow molecular weight distribution water soluble polymer standards sodium polystyrene sulfonate, NaPSS (Pressure Chemical Company, Pittsburgh, PA) and dextrans (Pharmacia Fine Chemicals, Piscataway, NJ). The universal calibration curve proposed by Grubisic et al. (13) was found not to be applicable for these polymer standards. The alternative calibration procedure of Coll and Prusinowski (J ) which incorporates excluded volume effects in the numerical value of the Flory parameter was found to be applicable for this system ( ). The calibration curve for the two-column network system described above is shown in Figure 3. The Kyyy parameter used on the abscissa of Figure 3 is a normalized elution volume parameter defined by Equation 1,... 

M /kg.mor = 100,M g.mor = 110, Pressure Chemical Company, Pittsburgh, PA diethyl oxalate C6H10O4... 

Pressure Chemical Company, Pittsburgh, PA methyl acetate C3H6O2... 

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