Densities of Octamethylcyclotetrasiloxane + Methane and 2,2-Dimethylpropane + Methane from 10 to 200 MPa and from 294 to 433 K

Abstract

Densities for octamethylcyclotetrasiloxane + methane and 2,2-dimethylpropane + methane have been determined in the one-phase region at temperatures between 294 and 433 K for a maximum pressure of 200 MPa in a piston cylinder apparatus. Polynomials capable of describing the density as a function of P, T, and composition have been derived.

Thermodynamic Properties of Octamethylcyclotetrasiloxane

“…Figure , top). Wappman et al utilized a sample with a purity of 99% for their measurements. The employed piston cylinder densimeter was described in detail by Wappmann et al The accuracy of the measurements was assessed with test measurements on methanol, which reproduced Goodwin’s data within 0.2%.…”

“…The employed piston cylinder densimeter was described in detail by Wappmann et al The accuracy of the measurements was assessed with test measurements on methanol, which reproduced Goodwin’s data within 0.2%. Without any further explanation, Wappmann et al stated an experimental uncertainty of 0.4% for octamethylcyclotetrasiloxane. The second data set of Easteal and Woolf shows an opposite trend with respect to the present equation of state.…”

“…The second data set of Easteal and Woolf shows an opposite trend with respect to the present equation of state. They investigated only one isotherm (323.15 K), which was not measured by Wappmann et al Therefore, it is not possible to compare these results directly with each other. Easteal and Woolf measured their density data with an even lower sample purity than Wappmann et al (98%) in a bellows volumometer .…”

Multiparameter equations of state for selected siloxanes

“…Isothermal subcooled liquid densities are reported only for D 4 : in Ref. [35] the authors state that their measurements are accurate to within 0.4%. Atmospheric subcooled liquid densities for D 4 are documented in Ref.…”

“…Fig. 4 shows a qualitative evaluation of the liquid P-v-T data by Wappmann et al for D 4 [35]: for a given isotherm, the molar density is plotted as a function of the pressure. All of the data points can be smoothly interpolated with a polynomial curve.…”