A modified method for the carboxyl end group titration of polyethylene terephthalate is presented. The main features of the method are: i) the use of a mixed solvent consisting of phenolchloroform 2:3 V/V to dissolve the polymer sample at 80-100℃ within 2-10 minutes to minimize the error due to thermal degradation of the polymer; ii) direct titration at room temperature; iii) the choice of a suitable indicator

tetrabromo-phenol blue

to give a very sharp end point; iv) the use of a benzyl alcohol solution of potassium hydroxide as titrant for good miscibility with the solution being titrated.