The main chain liquid cryatal polymers with X-shaped mesogens and different flexible spacers were synthesized by solution polycondensations using the monomers 4

4'-(alkylen-edioyldioxy) dibenzoyl dichloride and 2

5-dihydroxyl-1

4-phenylene di-p-ethoxybenzoate. The liquid-crystalline behaviour of the polymers was characterized by DSC

polyarizing microscope and X-ray diffractometre. It was found that at a temperature not much higher than the clearing point of the polymer melts the birefringence will reccur in a few minutes

This unu-sual behaviour of these polymers is explained as the result of molecular weight increase in the heating process.