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, CH3(CH3O)3Si) and tetramethyl orthosilicate (TMOS, (CH3O)4Si) 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 Ur (0.95 level of confidence) were Ur(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.