STUDY OF AN APPROPRIATE PROCEDURE FOR THE CHROMATOGRAPHIC ANALYSIS OFPOLY(ETHYLENE-TEREPHTHALATE), AFTER MELT PROCESSING WITH TRIPHENYL PHOSPHITE

The performance of a chromatographic technique for polyester analysis at a moderate temperature was investigated. Sample dissolution at room temperature in phenol-1,1,2,2-tetrachloroethane (TCE) and analysis at 70 degrees C in m-cresol, despite the efficiency for pure polyesters, proved to be inadequate for molecular mass determination of polyester /phosphite systems since it causes a rapid degradation of bonds create d by the phosphite in the molten state. Furthermore, the presence of t hree different solvents makes the technique highly complex. Large modi fications of the chromatographic conditions result, partly irreversibl y, from the injection of samples dissolved in phenol-TCE. A new proced ure, working close to room temperature with phenol-TCE eluent, was the refore developed, thus avoiding any polymer degradation and allowing f or the study of polyester/phosphite samples by size exclusion chromato graphy.