Abstract
HLB values of polyoxypropylene-polyoxyethylene blockpolyether type of high molecular weight have not yet been determined (except an unreported study by Schmolka and Lutwick), pherhaps because of their high molecular weight and particular properties of hydrophobic radical (consisted of semi-hydrophillic oxypropylene units).
HLB values of this type of nonionic surfactants were experimentally determined from required HLB value for solubilization of phenyl ethyl alcohol. Experimental attempt to determine HLB values from required HLB value for the emulsification was not successful. From comparison of the determined HLB values with cloud point (°C) or cloudy number (ml), the following empirical relations were obtained :
HLB value=0.0980x+4.02
and HLB value= 16.02 log A-7.34
where, x=cloud point (°C), and A= cloudy number (ml).
These empirical relations were independent on the number of functional -OH radicals of these nonionic surfactants of which molecular weights of hydrophobic polyoxypropylene per one -OH radical are larger than 9001, 000.
If these molecular weights are smaller than 9001, 000, above empirical relations were not applicable. This suggests that polyoxypropylene radical per one -OH radical of smaller molecular weight than 9001, 000 behaves incomplete hydrophobic radical.
