Polymorphic forms of o-benzylphenol and slow molecular motions in the amorphous state

Joaquim J. Moura Ramos, Susana Rocha, Hermínio P.Diogo (see publication in Journal )

This paper is about the number 1. The number 2 is left for future work.


The slow molecular motions in o-benzylphenol were studied by thermally stimulated depolarization currents (TSDC). No dipolar reorientational motions were found in the crystal, in the temperature region from −165 °C up to the melting temperature. Oppositely, a strong α-relaxation was detected in the amorphous solid state, but no local (secondary) relaxations were observed. The glass transition relaxation was characterized by TSDC, by conventional differential scanning calorimetry (DSC) and by modulated temperature differential scanning calorimetry (MTDSC). The fragility index of this glass forming system was determined based on data from the different techniques. The obtained values were m = 61 (DSC), m = 83 (MTDSC), and m = 65 (TSDC). Conventional DSC was used to identify the polymorphs of o-benzylphenol and their most favorable formation conditions. Two metastable polymorphs were observed, with melting temperatures near 15 and 21 °C.