The relaxation phenomena on phase and mesophase transitions
in poly(3-methyl-4,4'-dihydroxybenzophenone sebacate)
Polimery 1999, No 1, 45
Relaxation phenomena were studied on phase and mesophase transitions in poly(3-methyl-4,4'-dihydroxybenzophenone sebacate), aliquid crystalline polymer endowed with an experimentally convenient temperature range of mesophase existence. DSC thermograms (1, 5 or 10 K/min) were recorded from room temperature, at which the compound was crystalline, to the isotropization temperature (85°C), and in some cases up to 130°C (Figs. 2, 3). X-ray patterns were recorded (Figs. 4—8) and depolarized light intensity was measured in relation to temperature with a heated or cooled polymer film usedas depolarizer (Fig. 9). The data show liquid-crystalline thermotropic polymers to melt within a well-defined time and temperature range. Over 50—80°C, the crystalline phase coexisted with the mesophase, a fact not encountered inlow-molecular-weight pure liquid crystals. The joint application of DSC at varying heating rates and of thermooptic analysis provided complementary information on phase transitions in macromolecular liquid crystals.