Speeds of Sound and Isentropic Compressibilities of n-Alkoxyethanols and Polyethers with Propylamine at 298.15 K

The speeds of sound (u) have been measured at 298.15K and atmospheric pressure, as a function of composition for seven binary liquid mixtures of propylamine (CH3CH2CH2NH2, PA)+ethylene glycol monomethyl ether (2- methoxyethenol, CH3(OC2H4)OH, EGMME);+diethylene glycol monomethyl ether [{2-(2-methoxyethoxy)ethanol}, CH3 (OC2H4)2OH, Di-EGMME];+triethylene glycol monomethyl ether [{2-(2-(2-methoxyethoxy)ethoxy) ethanol}, CH3(OC2H4)3OH, Tri-EGMME];+diethylene glycol monoethyl ether [2- (2-ethoxyethoxy)ethanol, C2H5(OC2H4)2OH, Di-EGMEE];+diethylene glycol monobutyl ether [{2-(2-butoxyethoxy) ethanol}, C4H9(OC2H4)2OH, Di-EGMBE];+ diethylene glycol diethyl ether [bis(2-ethoxyethyl)ether, C2H5(OC2H4)2 OC2H5, DEGDEE]; and+diethylene glycol dibutyl ether [bis(2-butoxyethyl) ether, C4H9(OC2H4)2OC4H9; DEGDBE] using a Nusonic velocimeter based on the sing–around technique. These values have been combined with densities derived from excess molar volumes to obtain estimates of the molar isentropic compressibility KS,m, and their excess values KE S,m. The KE S,m values are shown to be negative for all mixtures over the entire composition range. The deviations uD of the speeds of sound from the values calculated for ideal mixtures have been obtained for all estimated values of mole fraction x1. The change of KE S,m and uD with composition and the number of – OC2H4 – units in the alkoxyethanol are discussed with a view to understand some of the molecular iInteractions present in alkoxyethanol – propylamine mixtures. Also, theoretical values of the molar isentropic compressibility of