EFFECT OF THE COAGULATION TEMPERATURE ON MEMBRANE-PROPERTIES OF ETHYLENE VINYL ALCOHOL COPOLYMER

The effect of coagulation temperature on the structure and properties of ethylene-vinyl alcohol copolymer (EVA) membrane was investigated. Membranes were prepared at different coagulation temperatures, from 0 degree C to 70 degree C. The water flux and the pore size increased with increasing the coagulation temperature up to 55 degree C and then decreased to 70 degree C. The membranes prepared between 0 degree C and 20 degree C has a finger-like void; the coagulation was very slow, owing to the higher viscosity of the polymer solution at low temperature. On the other hand, the membrane prepared above 50 degree C has small spherical micelles in the pore cell walls because of the lower viscosity of solution: above 70 degree C, the membrane tended to be plastsized by hot water.