Abstract
Experimental results reported by the auther in previous papers on flow birefringence and viscosity of highly concentrated aqueous solutions of nonionic surface active agents, with polyoxyethylene chains as the hydrophilic group, are summarized and some considerations are given on the structures of the solutions. The data cover the concentration range from 5 to 95% and the temperature range from 10 to 80°C. The concentration dependence of flow birefringence can be classified into four types with regard to the temperature, and the temperature dependence into three with regard to the concentration. These experimental results together with the data of cloud point and gelation temperature are possible to be arranged in diagrams illustrating the optical properties of their aqueous solutions. The solution structure, which shows positive or negative birefringence, is discussed in terms of hydrotropic liquid crytalline phase formed in the highly concentrated solutions of these nonionic surface active agents with the aid of the diagrams obtained.
