In this work, heat capacities for three linear siloxanes (hexamethyl disiloxane (MM), octamethyltrisiloxane (MDM), and decamethyltetrasiloxane (MD 2 M)) in the temperature range of 205.15À395.15 K and for two cyclic siloxanes (octamethylcyclotetrasiloxane (D 4 ) and decamethylcyclopentasiloxane (D 5 )) in the temperature range of 288.15À443.15 K have been measured with the help of a TianÀCalvert calorimeter. Furthermore, vapor pressures for the five mentioned compounds in the temperature range of 250À620 K and pressures from 2 mbar to 1 bar have been determined with the help of a Scott ebulliometer. The prediction of the heat capacities using the group contribution equation of state VTPR were improved by fitting the Twu parameters simultaneously to the new vapor pressure and heat capacity data. In addition, melting temperatures and heat of fusions for these five siloxanes have been measured using a differential scanning calorimeter (DSC). Furthermore, density measurements for the three linear siloxanes (MM, MDM, and MD 2 M) between 278 and 437 K and pressures up to 130 MPa were carried out using a vibrating tube densimeter. The densities were correlated with the TRIDEN model.

Thermal conductivities have been measured for three linear siloxanes [hexamethyl disiloxane (MM), octamethyltrisiloxane (MDM), decamethyltetrasiloxane (MD 2 M)], two cyclic siloxanes [octamethylcyclotetrasiloxane (D 4 ), decamethylcyclopentasiloxane (D 5 )], and a mixture of 50 mass % MDM þ 50 mass % MD 2 M in the temperature range from 290 to 520 K and the pressure range from 500 to 10000 kPa using the transient hot wire method and correlated with a temperatureÀpressureÀthermal conductivity relationship. Moreover, the thermal conductivities at atmospheric pressure were measured for MM, D 4 , D 5 , and MD 2 M. The data were compared with the available data from the literature for four compounds. Additionally, the viscosities of the five siloxanes were measured in the temperature range from 238 to 378 K at atmospheric pressure using a rotational Stabinger viscometer.

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Group contribution (GC) methods are widely used for predicting the thermodynamic properties of mixtures. They divide components into structural groups, which can be combined freely so that the applicability of...

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