Abstract
The thermotropic liquid crystalline(LC) copolyesters based on p-acetoxybenzoic acid (HBA), hydroquinone diacetate(HQ), and poly(ethylene terephthalate) (PET) units were pre- pared by melt polymerization. The effect of dissymetrical units and chemical composition on the properties of the copolyester were examined. The dissymetrical units employed included 1,1,3-trimethyl-3-phenylindan4',54icarboxylic acid (PIDA) , 5-te rt-butyl-1,3-bensenedicarboxy- lit acid (5-B/A) and 2,6- naphthalenedicarboxylic acid (2,6-NDA) , LC-copolyesters with an inherent viscosity in the range of 0.9 to 1.2 were obtained. All of these polymers exhibited turbid melts. The flexible PET units lower the glass transition and melting temperatures, storge modulus (I°) and deflection temperature of I°. The glass transition and deflection temperatures apparently increased with increasing PIDA, 5-B/A and 2,6-NDA contents in the main chain of copolyesters. The copolyesters containing 1 to 5 mole % PIDA or 5-B/A were found to have good thermal and mechanical Propereifs, with melt processing temperature below 300℃.
