Cellulose/casein blend membranes from NaOH/urea solution

Cellulose membranes and cellulose/casein blend membranes were successfully prepared from a new solvent system (6 wt % NaOH/4 wt Q urea aqueous solutio n) by coagulation with a sulfuric acid aqueous solution. The structures and properties of the membranes were characterized by Fourier transform infrar ed spectroscopy, scanning electron microscopy (SEM), wide-angle X-ray diffr action, differential scanning calorimetry, and a tensile test. The experime ntal results showed that the suitable coagulation condition was 5 wt % H2SO 4 for 5 min. When the cast;in content of the mixture was less than 15 wt %, the blend membranes were miscible because of the interactions between the hydroxyl groups of cellulose and the peptide bonds of casein. The blend mem branes with 10 wt % casein had good miscibility, higher crystallinity, and the highest mechanical properties and thermal stability. In this case, the tensile strength and breaking elongation of the blend membranes were 109 MP a and 16%, respectively, and its pore size, obtained by SEM, was 290 nm, wh ich suggests that the blend membranes provide a potential application for t he field of separation technology. (C) 2001 John Wiley & Sons, Inc.