ALKOXY-SUBSTITUTED LIQUID-CRYSTALLINE AROMATIC COPOLYESTERS .4. SYNTHESIS AND PROPERTIES OF MAIN-CHAIN COPOLYESTERS DERIVED FROM 2,5-BIS(PENTYLOXY)TEREPHTHALOYL DICHLORIDE AND TRANS-1,4-DIHYDROXYCYCLOHEXANE

Rigid rod copolyesters derived from 2,5-bis(pentyloxy)terephthaloyl di chloride (3), 4,4'-dihy-droxybiphenyl (4) and trans-1,4-dihydroxycyclo hexane (5) were synthesized and their thermal behavior analysed. The s tructures were characterized by H-1-NMR, GPC and elemental analyses; t heir thermal behavior was studied by DSC measurements, microscopy unde r polarized light and thermogravimetric analyses. The composition of t he copolyesters with 30, 50 and 70 mol % 5 was not as expected, due to the differing reactivities of the diols 4 and 5 during the polyconden sation. This led to the existence of two species of polyesters from on e reaction mixture. The higher the content of 5 in the polymer, the lo wer the molecular weight. By increasing the amount of 5, the thermal s tabilities and melting points decrease drastically, whereas the solubi lity increases. The copolyesters a-g show only a low ability to form f ibres which are brittle and break very easily.