抄録
Phenol-water mixture separates into two phases below 68°C in a certain range of concentration, but phenol-methanol-water mixture does not above a certain concentration of methanol. The fractionation of cellulose triacetate by phenol-methanol-water mixture at 25°C is studied in this experiment, where phenol-methanol-water (60:16:24) mixture is used as solvent, methanol-water (40:60) as precipitant. The fractionation method is the so-called “solution extraction” i.e. the most part of triacetate is precipitated, redissolved by heating up to 50°C, then the solution is let cool naturally over one night separating into two phases. The upper phase containing a small part of triacetate of the lowest DP is taken out, and the triacetate is precipitated, washed, dried, and weighed. The lower part is redissolved clearly by adding some phenol solution and two phases separation is repeated.
By this fractionation method, three samples of triacetate are compared on the uniformity of DP-distribution. The triacetate of ZnCl2-solution method has the highest uniformity and the triacetate of ZnCl2-vapour phase method the least.
