Observation of two glass transitions in a thermotropic liquid-crystalline polymer

摘要: DSC and real-time variable-temperature synchrotron experiments have been performed on a thermotropic poly(etherester), PH31B32, with biphenyl units as mesogens spacers methyl substituents. It has found that PH31B32 develops low-ordered SmCalt mesophase rather slow rate of formation in such way the isotropic melt this polymer can be easily quenched into glassy amorphous state at usual cooling rates calorimeter. Considerably high annealing times temperatures above Tg are necessary to develop mesophase. The extent transformation symmetry determined by means calorimetric X-ray diffraction experiments. results show glass-transition liquid-crystalline states clearly different:  95 84 °C, respectively. Moreover, isotropization temperature increases linearly (the which ...