A series of all-aromatic polyesters with high molecular weight derived from m-phthalic acid

4

4′-dihydroxybenzophenone

hydroquinone

and p-hydroxybenzoic acid were synthesized by direct polycondensation method in sulfonyl chloride (BsCI)

dimethylforamide (DMF) and pyridine (Py) at various bisphenols ratios．The liquid crystalline behaviors and thermal properties of the all-aromatic polyesters have been characterized by polarized light microscopy (PLM)

wide angle X-ray diffraction (WAXD)

thermogravimetric analysis and differential scanning calorimetry (DSC)．The results show that the all-aromatic polyesters with high molecular weight can be synthesized in an easily controlled mild condition as compared with the usual ester exchange reaction．Under polarizing optical microscope

all the synthesized polyesters with different ratios of bisphenols show a very high degree of birefringence with threaded nematic texture in the molten state and strip texture after shearing from the melt．Comparing the polyesters with those synthesized by melt ester exchange reaction

the polyesters have a good crystallinity from the result of WAXD studies．All the polymers show high thermal stability and the decomposition temperature range for 5％ weight loss is from 427℃ to 476℃

hut there is no significant difference between their temperature of maximum decomposition．The results of DSC show that the glass transition can not be obtained in the first heating process

and can be observed in the cooling and second heating processes．In the first heating run

there exist two evident endothermal transitions in ca．200℃ and 270℃

and in the second run

only one in ca．270℃．The polyesters have excellent fiber-forming capability with a potential for melt spinning.