Statistical‐graphical survey of series of linear and cyclic dimethylsiloxanes

Abstract

A study is made of the physical characteristics of linear and cyclic polysiloxanes. It is shown that by plotting v20/v70 versus v20 (v = kinematic viscosity) it is possible to determine the average number of silicon atoms per molecule in a mixture of linear and cyclic siloxanes, and the average ratio of silicon atoms in linear structure to those in cyclic structure and to predict physical constants of siloxanes when two of them are known.

Thermodynamic Properties of Dodecamethylpentasiloxane, Tetradecamethylhexasiloxane, and Decamethylcyclopentasiloxane

“…Figure 4 shows that all data are reproduced within 0.34%, which is well within that estimated uncertainty range. For D5, this estimate is confirmed by the vapor-pressure data point of Waterman et al, 56 which deviates by −0.2% from the value calculated with the thermodynamic model and from the measurement reported by Flaningam. 44 In contrast, deviations of 1.4% (MD3M) and 4.4% (MD4M) are observed for the linear siloxanes.…”

Speed of Sound Measurements and Fundamental Equations of State for Octamethyltrisiloxane and Decamethyltetrasiloxane

“…Moreover, they are supported by the data point of Golik and Cholpan. 33 Measurements of Sperkach and Cholpan 37 show positive deviations up to 3%, whereas the data point of Waterman et al 38 deviates by −2.6%. For both data sets, no information on the uncertainty is available so that the main focus was given to the correct description of the data measured in this work.…”

“…The equation of Colonna et al deviates by more than 15% because no density or speed of sound data at elevated pressures were available when that equation was developed. Only three data points of Waterman et al and Weissler at atmospheric pressure were available. However, they were still missed by about 10% because they were not included in the fitting procedure .…”

“…Figure 7 shows that the new equations of state reproduce these data within the assumed uncertainty. For MDM, only five data points out of 459 exhibit a deviation above 0.1% (maximum deviation: 0.11%) 42 1 293.14 0.101325 0.25 Golik and Cholpan 33 1 303.13 0.101325 0.058 Hunter et al 43 1 298.14 0.101325 0.33 Hurd 34 5 273−354 0.101325 0.034 Matteoli et al 44 1 303.15 0.101325 0.53 McLure et al 36 16 299−413 0.101325 0.12 Povey et al 45 1 293.15 0.101325 0.03 Waterman et al 38 from the present equation of state. For MD 2 M, the highest isotherm (T = 437 K) is represented with deviations between 0.1% and 0.15%.…”

“…For the same reason as in the case of MDM, the equation of Colonna et al 4 again exhibits large deviations of up to 16%. The available data of Waterman et al 38 and Weissler 39 were not considered by Colonna et al 4 so that deviations of up to 14.5% can be observed. These deviations were reduced to approximately 0.5% in the present work.…”