A new method to control the polyesterification process. Prospects of application in the production plants

The progress of the polycondensation reaction in a simple system of a diol and a dibasic acid without another acid as catalayst was studied by determining the Acid Number (AN) on one hand and the amount of the produced water on the other. The system was submitted to different, suitable isothermal and non isothermal heating programs, that lead to the formation of a polyester with Acid Number AN = 40. In general this value constitutes the basis of a technological application of polyester. Then the kinetics of the polyesterification was studied, a mathematical calculation was deduced from the experimental results of AN as well as of the produced water. Two fundamental equations were expressed for both kinds of measurements: an empirical equation and a theoretical one, which contain the kinetic constants of polycondensation as parameters, e.g. activation energy, etc., and which were determined from the above‐mentioned kinetical study of the reaction. Further, the determination of the parameters for the theoretical as well as for the empirical equation was done at different ranges taking into consideration the time from the beginning of heating. From the mathematical model which is based on the measurements of produced water, it is possible to follow continuously the process of polyesterification, contrary to the discontinuous determination of the AN. In addition measurements of the viscosity during the progress of polyesterification may be done in the future, with the aim to contribute to the mathematical model for an effective reaction observation and control of the quality of polycondensates.