THERMODYNAMICS OF AQUEOUS MIXTURES OF POLYOXYETHENE GLYCOL MONOETHERS- IV - EXCESS MOLAR VOLUMES OF (N-OCTYL TETRAOXYETHENE GLYCOL MONOETHER PLUS WATER) IN THE VICINITY OF THE CRITICAL MICELLE COMPOSITION

Excess molar volumes of an aqueous solution of a non-ionic surfactant: n-octyl tetraoxyethene glycol monoether, {CH3(CH2)(7)O(CH2CH2O)(4)H} (''C8E4'') have been investigated as a function of temperature in the high dilute region, i.e. the region in the vicinity of the critical mi celle composition (c.m.c.). The measurements have been made at the tem peratures (278.149, 288.146, 298.144, and 308.141)K. In this study, V- m(E) is negative and increases with temperature; V-m(E)(x) changes slo pe for x = (0.00024, 0.00020, 0.00017, and 0.00013) at the temperature s (278.149, 288.146, 298.144, and 308.141)K, respectively. The results for V-m(E) have been fitted with an association model, and the values of the aggregation number N, Delta V-m,V-micell and the critical mice lle composition have been extracted. (C) 1997 Academic Press Limited.