Isosorbide as a Molecular Glass: New Insights into the Physicochemical Behavior of a Biobased Diol

This paper presents a study of the thermal and rheological properties of isosorbide, showing that its degradation temperature (around 100 °C) is much lower than values previously proposed in the literature. Furthermore, remarkable calorimetric and viscoelastic behaviors, with features usually observed in semi-crystalline systems are presented. The onset of the melting is measured at 45 °C, while a glass transition occurs at -45 °C, followed by cold crystallization. Wide-angle X-ray diffraction confirmed the coexistence of crystalline domains and an amorphous fraction, which behaves as a molecular glass, with an estimated crystallinity of approximately 70%. Thermogravimetric analyses conducted under both air and nitrogen and at multiple heating rates, in line with ICTAC recommendations, established the robustness of the 100 °C degradation onset. These findings provide new structure-property relationships for isosorbide and open up new avenues for further research and development in this area.