Pressure–Volume–Temperature Relationships of Trimethoxymethylsilane and Tetramethyl Orthosilicate at Temperatures Ranging from 303.2 to 363.2 K and Pressures up to 160 MPa

Abstract

The pressure−volume−temperature (PVT) relationships for trimethoxymethylsilane (MTMS, CH 3 (CH 3 O) 3 Si) and tetramethyl orthosilicate (TMOS, (CH 3 O) 4 Si) were measured at temperatures ranging from 303.2 to 363.2 K and pressures up to 160 MPa. Density measurements were carried out with an experimental apparatus based on the variable volume method. The standard uncertainties u(T) = 0.17 K and u(P) = 0.14 MPa, and the relative combined expanded uncertainty U r (0.95 level of confidence) were U r (ρ) = (0.0016 and 0.0022) for MTMS and TMOS, respectively. The obtained PVT relationships were correlated using the Tait equation and the Sanchez− Lacombe equation of state to determine the characteristic parameters.

Pressure–Volume–Temperature Relationships of Tetraethyl, Tetrapropyl, and Tetrabutyl Orthosilicates

“… a Characteristic parameters of pure component P *, T *, and ρ*; number of lattices occupied by a molecule r ; interaction energy between segments ε*; and lattice volume v *. b Reported in a previous work c Obtained by correlating the PVT data reported by Yokoyama et al …”

“…In this work, the PVT relationships were measured using a general, variable-volume method. Details of the apparatus used and procedures employed have been described in a previous work …”

“…The maximum relative expanded uncertainty U r of density with a confidence level of 0.95 was estimated to be 0.0022, 0.0037, and 0.0027 for TEOS, TPOS, and TBOS, respectively. The methods underlying these calculations have been detailed in a previous work . Briefly, the combined standard uncertainty of the experimental density determined in this work was calculated according to the following equation where u ρ , u P , and u T are the standard uncertainties of density, pressure, and temperature, respectively, and (∂ρ/∂ P ) and (∂ρ/∂ T ) indicate the sensitivity coefficients for the density.…”

“…Yokoyama et al studied the densities of TEOS under high pressures, and Nikitin et al measured the critical properties of 10 different TAOS and compared them with values estimated from the group contribution method. We have also reported on the PVT relationships of trimethoxymethylsilane ((CH 3 O) 3 (CH 3 )­Si) and TMOS in a previous study …”

“…We have also reported on the PVT relationships of trimethoxymethylsilane ((CH 3 O) 3 (CH 3 )Si) and TMOS in a previous study. 18 Although comprehensive knowledge of physicochemical properties is essential, it is impossible to measure them for all substances under all conditions. Equations of state (EoS) help solve this conundrum by correlating various physical properties with each other (and thus enabling their estimation).…”