Thermal behavior of saturated phthalic-type polyesters. Influence of the branching polyol

The influence of the branching polyol on the thermal behavior of phthalic anhydride (PA)–polyol polyesters was determined under non-isothermal conditions. The polyol was glycerol, trimethylolpropane, and pentaerythritol, used in a molar ratio of 1.5:1, 1.5:1, and 2:1 in respect of anhydride, respectively. The thermal behavior of the synthesized polyesters was qualitatively estimated by the thermoanalytical curves obtained at a heating rate of 10 °C min −1 . Quantitatively, the thermal behavior of the prepared polyesters was studied by a kinetic analysis using three different methods: Friedman, Flynn–Wall–Ozawa, and modified nonparametric kinetic method. By all the samples, two thermodegradation steps were observed. The beginning of the first step of degradation was considered the qualitative criterion for the thermal stability estimation: The pentaerythritol-containing polyester was the most thermostable, until 195 °C. Also the kinetic analysis the same sample presented the highest activation energy, i.e., the lowest thermodegradation rate.