Dilatometer high-pressure

The dilatometer stem is coaxially enclosed in an open-ended stainless-steel sheath which serves as one plate of a capacitor in a manner similar to the sheath used in the high-pressure porosimeter. When connected to the capacitance bridge of the porosimeter, the filling apparatus, using its own low-pressure transducer, measures the intruded volume and continuously plots the data on an X-Y recorder up to 24 psia. 

The first bomb used by Ritter and Drake was limited to 2000 psi and used a commercial insulated electrical wire lead to the dilatometer they had developed. After publishing their first two papers, the authors learned that the Rusha Instrument Corp., Houston, Texas has marketed for a number of years a "high pressure porometer" which forced mercury by means of a tight piston into oil-well (12). However, the Rusha instrument only operated to 1000 psi (2100 A pores). 

Density and specific volume of mesophases are measured under atmospheric pressure with pycnometers [17-22], dilatometers [16, 23-25] (e.g., differential scanning dilatometers, DSD [26-31]), with a buoyancy method [32], and with a vibrating device, known as a digital precision density meter system, or densitometer (Anton Paar K.G.) [33-38], Devices for high-pressure measurements of specific volumes have been described by Kuss [39,40] and Ddrrer et al. [41], but were also mentioned earlier [42], More recently, a device for simultaneous... 

MIP measurements were carried out with a low-pressure (Pascal 140, Theromo Fisher Scientific, Milano, Italy) and a high-pressure unit (Porosimeter 2000, Carlo Elba, Milano, Italy). The low-pressure unit was used with an evaluable pressure range of 0.13 bar to detect pore radii between 58 and 1.84 pm. The same dilatometer is then placed to the high-pressure unit, which operates from atmospheric pressure up to 2000 bar to evaluate pore radii from 7355 to 3.7 nm. The mathematical relationship of pressure to pore radius distribution is calculated with the Washburn equation [37], assuming that all pores are cylindrical. Each experiment was performed in triplicate [32]. 

The Carlo Erba 2000 operates in the 0-20 MPa pressure range to measure pore diameters down to 7.5 nm. As the pressure is increased in steps from vacuum to one atmosphere, macropores with diameters in excess of IS pm are measured. The dilatometer is then placed in a high pressure unit in order that mesopores can be measured. The mercury level in the dilatometer stem is electrically followed by means of a capacitive system. The instrument has a programmable delay which permits the system to come to equilibrium at each step. 

Under Kurt Uberreiter further research was carried out on the thermodynamic properties of polymers and their solutions. In addition, Uberreiter oversaw research into topics such as crystallization delaying and accelerating structural elements and the relationship between molecular structure and macroscopic properties. This included the first measurement in polymer solutions of effects from configuration on surface tension. Members of the department aiso built a wide array of instruments, such as high pressure dilatometers, differential refractometers... 

If one is using a solvent of relatively high vapour pressure the solvent will tend to distil from the residual reaction mixture in the mixing chamber into the capillary because of the difference in vapour pressure between surfaces of different curvature. This can be prevented by incorporating a dry-joint (see p. 47) between the top of the capillary as shown in Fig. 3.12, or by incorporating a small length of capillary with the same i.d. as that used for the dilatometer, as shown in Fig. 3.14. 

Accuracy density data were obtained with high temperature dilatometers, where the solution is contained in a stainless-steel autoclave connected through a capillary tube to a mercury reservoir thermostatized at 25 °C. When the sample autoclave is heated, the solution expands and the excess mercury is discharged into a weighing bottle, to keep the pressure constant. 

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