Harry C. Hershey

A (p, V, T) study of tetramethylsilane, hexamethyldisiloxane, octamethyltrisiloxane, and toluene from 423 to 573 K in the vapor phase

A Kay-type apparatus was used to measure (p, V, T) of gaseous tetramethylsilane, hexamethyldisiloxane, octamethyltrisiloxane, and toluene from about 423 K to 573 K. Second virial coefficients were computed for all temperatures. No experimental (p, V, T) values are reported in the literature for octamethyltrisiloxane. The present measurements constitute a significant extension of available results for hexamethyldisiloxane, since the only previous values were for lower temperatures. The results for tetramethylsilane resolved a conflict concerning the second virial coefficient. The results for toluene confirmed previous reports and served, along with the tetramethylsilane values, to verify our experimental and calculational procedures. Agreement of the second virial coefficients with existing literature values is satisfactory.

Mass transfer at the wall as a result of coherent structures in a turbulently flowing liquid

Abstract A direct numerical calculation of the instantaneous mass transfer at a solid boundary was made from a one-dimensional mass balance equation with the only input Information being the normal velocity. This velocity was generated on the computer so as to have the gross characteristics of the normal velocity obtained from turbulence experiments. The average mass-transfer rate was adequately predicted. Other characteristics of the scalar field are reported.

The orthobaric region of octamethyltrisiloxane

Abstract A Kay-type mercury-in-glass apparatus and a Sweitoslawski ebulliometer were used to study the orthobaric region of pure octamethyltrisiloxane. Bubble and dew point densities were determined experimentally in the range 426.17–564.13 K. The critical volume was determined from these data using the law of rectilinear diameters. The critical point for octamethyltrisiloxane was determined as follows: critical pressure, 1415 kPa; critical temperature 564.13 K; critical volume, 0.8818 m 3 kmol −1 ; critical compressibility, 0.266. Liquid densities were measured pycnometrically in the range 273.12–361.82 K to resolve discrepancies reported by previous investigators. We determined the density at 298.15 K to be 814.70 kg m −3 . The vapor pressure of octamethyltrisiloxane was determined from 2.08 kPa (322.44 K) to the critical point, 1415 kPa (564.13 K). These data were correlated by two versions of the four constant Wagner equation and by the DIPPR equation. Our vapor pressure measurements compare favorably with those of previous investigators. In addition, our vapor pressure data were used to obtain the acentric factor (0.531) and the normal boiling point (425.68 K).

Isothermal p, x, y relations, activity coefficients, and excess Gibbs free energies for heptamethyltrisiloxane + toluene at 343.15, 363.15, and 383.15 K

Vapour-liquid equilibrium relations have been determined at 343.15, 363.15, and 383.15 K for heptamethyltrisiloxane + toluene. The isothermal variation of the total pressure with the composition of the equilibrium liquid and vapor phases was determined experimentally in a recirculating still over the entire composition range. Using Barkers method to calculate the vapour-phase composition, the activity coefficients and excess Gibbs free energy were calculated for each liquid composition. At 343.15 K, the curve of GE against x is asymmetric but as the temperature is increased GE decreases and passes through a minimum point in the heptamethyltrisiloxane-rich region, whereas, in the toluene-rich region, the maximum value of GE decreases and goes through a minimum. The S-shaped curves that are formed indicate an interesting variation in the intramolecular forces of the components with the temperature. Vapour pressures, the normal boiling temperature, liquid densities, and the critical properties are reported for heptamethyltrisiloxane.

Solution properties of association colloids of twelve aluminum monohydroxy disoaps in nonaqueous solutions

Abstract This paper reports the micellar properties of 12 aluminum disoaps in nonaqueous solutions, many of which have not been synthesized previously. Measurements of light scattering, sedimentation velocity in an ultracentrifuge, and viscosity were made on various concentrations of six straight-chain and six branched monohydroxy aluminum disoaps in toluene or trichloroethylene. All these soaps formed association colloids in toluene solutions. Molecular weights of the micelles formed by these soaps ranged from 3 million to 45 million. Sedimentation velocity experiments showed that each soap forms a monodisperse micelle. Light mattering measurements pointed out the importance of the structure of the organic soap molecule in establishing micellar properties. The two most stable soaps prepared were the aluminum dioctoate and the di-2-methylundecanoate, which formed elongated micelles. Soaps with methyl groups near the tail were less asymmetric and less stable. For example, di-3-ethylheptanoate was less stable than the dioctoate (di-2-ethylhexanoate). The micellar molecular weight and CMC for solutions of the six straight chain disoaps increased gradually as the number of carbon atoms increased. Viscosity measurements of aluminum distearate in toluene were used to determine the relative strength of peptizing agents and to quantify time-dependent behavior. Amines were the strongest peptizing agents, followed by alcohols and acids. The presence of water decreased the solution viscosity over several days throughout the concentration range investigated.