NONEQUILIBRIUM THERMAL-BEHAVIOR OF A MAIN-CHAIN THERMOTROPIC POLYMER

The effect of thermal treatment on the thermodynamic properties and st ructure of a nematic thermotropic main chain polymer with mesogenic gr oups containing 3,3'-biphenylene units and octamethylene flexible spac ers (BF8) has been studied by DSC and X-ray scattering. We have found that BF8 samples do not crystallize even on very slow cooling from the isotropic state, and possessed a glassy nematic structure at room tem perature. The strong influence of the cooling rate on both the enthalp y of the nematic-isotropic transition and the rise of specific heat at the glass transition for BF8 samples was observed. It was attempted t o explain this result in terms of the improvement of the nematic struc ture during cooling.