Improvement on multiparameter equations of state for dimethylsiloxanes by adopting more accurate ideal-gas isobaric heat capacities: Supplementary to P. Colonna, N.R. Nannan, A. Guardone, E.W. Lemmon, Fluid Phase Equilib. 244, 193 (2006)

Abstract

A recent paper by the authors reports ideal-gas isobaric heat capacities ( C P 0 ) for several siloxanes. These values were determined using ad hoc speed-of-sound measurements and ab initio calculations. Thermodynamic models for some siloxanes documented in an earlier work by the same authors adopted less accurate estimations for C P 0 ( T ) . This note reports coefficients for the substance-specific Aly–Lee correlations for C P 0 ( T ) which ensure higher accuracy when used with the multiparameter equations of state for fluids [(CH 3) 2–Si–O] 4 (D 4, octamethylcyclotetrasiloxane), [(CH 3) 2–Si–O] 5 (D 5, decamethylcyclopentasiloxane), (CH 3) 3–Si–O–Si–(CH 3) 3 (MM, hexamethyldisiloxane), and (CH 3) 3–Si–O–[(CH 3) 2–Si–O] 4–Si–(CH 3) 3 (MD 4M, tetradecamethylhexasiloxane), as described in Colonna et al. [P. Colonna, N.R. Nannan, A. Guardone, E.W. Lemmon, Multiparameter equations of state for selected siloxanes, Fluid Phase Equilib. 244 (2) (2006) 193–211].