A MODIFIED SYNTHESIS OF LIQUID-CRYSTALLINE POLY(ETHYLENE TEREPHTHALATE-CO-OXYBENZOATE)S WITH COMPLETELY RANDOM CHAIN STRUCTURE

A new method for synthesis of liquid-crystalline poly(ethylene terepht halate-co-oxybenzoate)s (PET/HBA) is proposed. In order to prevent for mation of PET-rich phases, complex monomers were used instead of PET, In comparison to copolyesters synthesized conventionally, the new prod ucts proved to be much more homogeneous. C-13 NMR measurements evidenc ed that the chain segment distribution is almost random. In contrast t o literature data for a copolyester composition of PET/HBA (50/50 mol/ mol) only a single glass transition was detected by dynamic mechanical analysis. The influence of transesterification reactions on the homog eneity is discussed.