SearchPublisher and Institutes
You are here: Home :: Area NEM :: Chemistry :: Physical chemistry
A.L.G. Saad, Y. Barakat, S.A. El-Kholy, A.I. Mead
Relaxation Behaviour and Dipole Moment of Some Nonionics. II. CMC and Thermodynamics of Ethoxylated Alkylphenols in Nonaqueous Medium
The relaxation behaviour of octylphenol-, nonylphenol- and dodecylphenol ethoxylates in benzene solutions has been studied in the frequency region 0.2 to 18 GHz at 20, 30 and 40°C. The critical micelle concentration (CMC) values of these nonionic surfactants have been located from the relaxation time-concentration and dipole moment-concentration plots through the least-squares regression analysis. The effects of the hydrophobic chain length (R) and the hydrophilic polyoxyethylene (POE) chain length on the determined CMC values, have been investigated. The thermodynamic parameters Δ F, Δ H and Δ S, which represent the change of free energy, activation energy and entropy have been determined at concentrations up to micelle formation. The obtained thermodynamic parameters have been discussed in terms of the molecular behaviour.
Zeitschrift für Physikalische Chemie, Oldenbourg Wissenschaftsverlag
Print ISSN: 0942-9352
Volume: 205, 02/1998
Pages: 167