The elastic properties of hexatriacontane single crystals at their various phase transitions

For the first time the elastic properties of solution grown hexatriacontane (C36H74) single crystals are investigated between room temperature and the melt transition by Brillouin spectroscopy. In addition to the transitions reported in the literature a further low temperature phase is found and confirmed by DSC measurements. It turns out that the elastic stiffness in the molecular chain direction is only 11 GPa at 71 °C. The temperature dependence of the sound velocity in the rotator phase is brought into connection with the dynamics of kink formation. Elastic properties between room temperature and the melt transition are also reported for melt crystallized pentacosan (C25H52).