The critical micelle concentration of Teric X10 by the small rod-in-free-surface method of surface tension measurement

Abstract

The rod-in-free-surface method using a small rod (0.748 mm in diameter) is shown to be an excellent method of surface tension measurement. The CMC at 50°C of the non-ionic surfactant Teric X10 is found by this method to be 0.168 mmol dm −3, in good agreement with the value 0.173 mmol dm −3 obtained by the pendent drop method. Both methods reveal time-dependent surface properties at concentrations below the CMC.